Discussion 3

Read chapter XIII and XIV

In the commentary, answer these questions:

• In your own words, what was the intent of this author?
• What was the goal of the book/particular chapter?
• What key term(s) stood out to you from the author’s work?
• Which chapter resonated with you most and why?
• Why does a book like this fit into the context of this course?
• Share a concept, theme, or excerpt that left a strong impression or that raises important questions.
• Conclude your video with a question and/or line of questioning for your peers that will solicit their unique ideas and responses.

Books by Edward T. Hall
THE SILENT L A N G U A G E
THE HIDDEN DIMENSION
H A N D B O O K FOR PROXEMIC RESEARCH
THE FOURTH DIMENSION IN ARCHITECTURE:
The Impact of Building on Man’s Behavior
(with Mildred Reed Hall)
THE DANCE OF LIFE:
The Other Dimension of Time
HIDDEN DIFFERENCES:
Doing Business with the Japanese
(with Mildred Reed Hall)
BEYOND CULTURE
ANCHOR BOOKS EDITIONS, 1969, 1990
Copyright © 1966, 1982 by Edward T. Hall
All rights reserved under International and Pan-American Copyright
Conventions. Published in the United States by Anchor Books, a
CONTENTS
division of Random House, Inc., New York, and simultaneously in
Canada by Random House of Canada Limited, Toronto. Originally
published in hardcover in the United States by Doubleday in 1966.
The Anchor Books edition is published by arrangement with
Doubleday, a division of Random House, Inc.
Anchor Books and colophon are registered trademarks of
Random House, Inc.
All photographs were taken by the author, with the following exceptions:
Plate 1, Sven Gillsater; Plate 3, H. Hediger; Plate 5, Bud Daley, Chicago Daily
News; Plate 8, Serge Boutourline; Plate 2 1 , Howard F. Van Zandt; Plate 23, Judith
Yonkers; Plate 25, Hedrich-Blessing.
AUTHOR’S PREFACE
I.
CULTURE AS COMMUNICATION
1
II.
DISTANCE REGULATION IN ANIMALS
7
Spacing Mechanisms in Animals
Flight Distance
Critical Distance
Contact and Non-Contact Species
Personal Distance
Social Distance
Population Control
The Stickleback Sequence
Malthus Reconsidered
The Die-off on James Island
Predation and Population
Grateful acknowledgment is made for permission to use excerpts from copyrighted
material, as follows:
From The Painter’s Eye by Maurice Grosser. Copyright © 1951 by Maurice
Grosser. Reprinted by permission of Holt, Rinehart and Winston, Inc.
From Language, Thought, and Reality, selected writings of Benjamin Lee
Whorf, by permission of The M.I.T. Press, Cambridge, Massachusetts. Copyright
© 1956, by The Massachusetts Institute of Technology.
From The Making of the President ig6o by Theodore H. White. Copyright © 1961
by Atheneum House, Inc. Reprinted by permission of the publishers.
From “Prologue: The Birth of Architecture,” Copyright © 1965 by W. H. Auden.
Reprinted from About the House, by W. H. Auden, by permission of Random
House, Inc.
Library of Congress Cataloging-in-Publication Data
Hall, Edward Twitchell, 1 9 1 4 The hidden dimension / Edward T. Hall,
p.
cm.
Reprint. Originally published: Garden City,
N.Y.: Doubleday, 1966.
Includes bibliographical references.
1. Spatial behavior. 2. Personal space.
3. Architecture—Psychological aspects.
4. City planning—Psychological aspects.
I. Title.
BF469.H3 1990
90-34870
304.2’3—dc20
CIP
ISBN 0-385-08476-5
www.anchorbooks.com
Printed in the United States of America
46 48 50 49 47 45
IX
III.
10
11
12
13
13
14
15
16
18
19
21
CROWDING AND SOCIAL BEHAVIOR IN ANIMALS
23
Calhoun’s Experiments
Design of the Experiment
Development of the Sink
Courting and Sex
Nest Building
Care of the Young
Territoriality and Social Organization
Physiological Consequences of the Sink
Aggressive Behavior
The Sink that Didn’t Develop
Summary of Calhoun’s Experiments
23
25
26
27
28
28
29
30
30
31
31
THE HIDDEN DIMENSION
The Biochemistry of Crowding
Exocrinology
The Sugar-Bank Model
The Adrenals and Stress
The Uses of Stress
IV.
PERCEPTION OF SPACE: DISTANCE RECEPTORSEYES, EARS, AND NOSE
Visual and Auditory Space
Olfactory Space
The Chemical Basis of Olfaction
Olfaction in Humans
V.
Hidden Zones in American Offices
Thermal Space
Tactile Space
VISUAL SPACE
Vision as Synthesis
The Seeing Mechanism
Stereoscopic Vision
VII.
ART AS A CLUE TO PERCEPTION
Contrast of Contemporary Cultures
Art as a History of Perception
VIII.
32
33
34
35
39
X.
41
42
45
46
49
XI.
THE LANGUAGE OF SPACE
52
54
60
65
66
70
73
77
91
Literature as a Key to Perception
94
I X . THE ANTHROPOLOGY OF SPACE: AN ORGANIZING MODEL
101
Fixed-Feature Space
Semifixed-Feature Space
Informal Space
103
108
111
PROXEMICS IN A CROSS-CULTURAL CONTEXT:
GERMANS, ENGLISH, AND FRENCH
The Germans
Germans and Intrusions
The “Private Sphere”
Order in Space
The English
Using the Telephone
Neighbors
Whose Room Is the Bedroom?
Talking Loud and Soft
Eye Behavior
The French
Home and Family
French Use of Open Spaces
The Star and the Grid
51
79
80
DISTANCES EST MAN
The Dynamism of Space
Intimate Distance
Personal Distance
Social Distance
Public Distance
Why “Four” Distances?
PERCEPTION OF SPACE: IMMEDIATE RECEPTORS
—SKIN AND MUSCLES
VI.
CONTENTS
XII.
PROXEMICS IN A CROSS-CULTURAL CONTEXT:
JAPAN AND THE ARAB WORLD
vii
113
114
116
119
121
123
125
131
131
132
134
136
138
140
141
142
142
143
144
144
146
146
149
Japan
149
How Crowded Is Crowded?
152
The Japanese Concept of Space Including
the Ma
152
The Arab World
154
Behavior in Public
154
Concepts of Privacy
157
Arab Personal Distances
159
Facing and Not Facing
160
Involvement
162
Viii
THE HIDDEN DIMENSION
Feelings about Enclosed Spaces
Boundaries
XIII.
CITIES AND CULTURE
The Need for Controls
Psychology and Architecture
Pathology and Overcrowding
Monochronic and Polychronic Time
The Automobile Syndrome
Contained Community Buildings
Prospectus for City Planning of the Future
XIV.
PROXEMICS AND THE FUTURE OF MAN
Form vs. Function, Content vs. Structure
Man’s Biological Past
The Need for Answers
You Can’t Shed Culture
APPENDIX
162
163
165
167
169
171
173
174
177
178
181
182
184
186
188
191
Summary of James Gibson’s Thirteen Varieties of
Perspective as Abstracted from The Perception of
the Visual World
BIBLIOGRAPHY AND REFERENCES
197
INDBX
209
AUTHOR’S PREFACE
Generally speaking, two types of books interest the serious
reader: those that are content oriented—designed to convey
a particular body of knowledge—and those that deal with
structure—the way in which events are organized. It is doubtful if an author has any control over which of these two types
of books he or she writes, though it is desirable to be aware
of the difference. The same applies to the reader whose satisfaction depends largely on unstated expectations. Today, when
all of us are overwhelmed with data from many sources, it
is easy to understand why people feel that they are losing
touch, even in their own field. In spite of television, or possibly because of it, people feel a loss of relatedness to the world
at large. Information overload increases the need for organizing frames of reference to integrate the mass of rapidly changing information. The Hidden Dimension attempts to provide
such an organizing frame for space as a system of communication, and for the spatial aspects of architecture and city
planning.
Books of this type, since they are independent of disciplinary lines, are not limited to a particular audience or field.
This lack of disciplinary orientation will disappoint readers
searching for pat answers and those who wish to find everything classified in terms of content and profession. However,
since space relates to everything, it is inevitable that this book
would cross disciplinary lines.
In writing about my research on people’s use of space—
the space that they maintain among themselves and their fellows, and that they build around themselves in their cities,
their homes, and their offices—my purpose is to bring to
THE HIDDEN DIMENSION
AUTHOR’S PREFACE
awareness what has been taken for granted. By this means,
I hope to increase self-knowledge and decrease alienation. In
sum, to help introduce people to themselves.
Regarding the organization of the book, I must mention
that as an anthropologist I have made a habit of going back
to the beginning and searching out the biological substructures
from which human behavior springs. This approach underscores the fact that humankind is first, last, and always a biological organism. The gulf that separates humans from the
rest of the animal kingdom is not nearly as great as most
people think. Indeed, the more we learn about animals and
the intricate adaptation mechanisms evolution has produced,
the more relevant these studies become for humans in their
search for the solution to many complex human problems.
All of my books deal with the structure of experience as
it is molded by culture, those deep, common, unstated experiences which members of a given culture share, which they
communicate without knowing, and which form the backdrop
against which all other events are judged. Knowledge of the
cultural dimension as a vast complex of communications on
many levels would be virtually unnecessary if it were not for
two things: our increasing involvements with people in all
parts of the world, and the mixing of subcultures within our
own country as people from rural areas and foreign countries
pour into our cities.
It is increasingly apparent that clashes between cultural systems are not restricted to international relations. Such clashes
are assuming significant proportions within our own country
and are exacerbated by the overcrowding in cities. Contrary
to popular belief, the many diverse groups that make up our
country have proved to be surprisingly persistent in maintaining their separate identities. Superficially, these groups may
all look alike and sound somewhat alike, but beneath the
surface are manifold unstated, unformulated differences in
their structuring of time, space, materials, and relationships.
It is these very differences that often result in the distortion
of meaning, regardless of good intentions, when peoples of
different cultures interact.
As a consequence of writing this book, I have been invited
to lecture to hundreds of architectural audiences all over the
United States and to consult on architectural projects. These
talks and consultations have been instructive and constitute
a body of data on social change. One of my objectives has
been to communicate to architects that the spatial experience
is not just visual, but multisensory. And that people differ in
their capacity to visualize—in the quality and intensity of their
visual imagery. Some people cannot visualize a house or a
room or a garden or a street intersection until after the work
has been completed. Architects do not have this problem,
which is why they can be architects, but they forget that their
clients may lack this ability. A third goal was to establish once
and for all that while buildings and towns cannot make up
for social injustice, and much more than good city planning
is needed to make a democracy work, there is still a close
link between mankind and its extensions. No matter what
happens in the world of human beings, it happens in a spatial
setting, and the design of that setting has a deep and persisting
influence on the people in that setting.
My greatest success in promulgating these ideas has been
among the younger architects. Bits and pieces of my research
have been accepted and applied, but not the organizing frame
which includes the idea that everyone receives all information
about the environment through his or her senses. If one wants
to understand the impact of the environment on human beings, it is necessary to know a great deal about the senses
and how sensory inputs are handled in the brain.
I have always believed in the importance of aesthetics in
architecture, but not at the expense of the people housed in
the buildings. Unfortunately, today most buildings communicate in no uncertain terms that designing for people is low
on our scale of priorities. All too often architects and planners
are hamstrung by decisions made by financial experts concerned with “the bottom line.” Financial calculations are seldom based on any understanding of human needs or the ultimate costs of ignoring them.
People need to know that they are important and that architects and planners have their welfare in mind, but it is a rare
structure that communicates this basic message. In the context
of international relations, it is also important to know that
THE HIDDEN DIMENSION
xu
the language of space is just as different as the spoken language. Most important of all, space is one of the basic, underlying organizational systems for all living things—particularly
for people. Why these statements are true is the subject of
this book.
No book reaches a point suitable for publication without
the active cooperation and participation of a great many people, all essential. There are always particular members of the
team whose roles are more clearly defined and without whose
help the manuscript would never have reached the publisher.
It is the contribution of these people that I wish to acknowledge.
The first need of authors is for someone to stick with them,
to put up with their exasperated impatience when it is pointed
out that they have failed to distinguish clearly between what
they know and what they have written. For me, writing is
something that does not come easily. When I am writing,
everything else stops. This means other people must shoulder
a heavy burden. My first acknowledgment is, as always, to
my wife, Mildred Reed Hall, who is also my partner in my
work and who assisted me in my research in so many ways
that it is often difficult to separate her contributions from my
own.
Support for my research has been generously provided by
grants from the National Institute of Mental Health and the
Wenner-Gren Foundation for Anthropological Research. I
wish to make special mention of a unique institution, the
Washington School of Psychiatry. As a Research Fellow of
the school and a member of its faculty for many years, I
profited enormously from my interaction with its creative
work.
The following editors aided me in the production of this
manuscript: Roma McNickle; Richard Winslow and Andrea
Balchan of Doubleday; and my wife, Mildred Reed Hall.
Without their help I could not have produced this volume.
I received valuable and loyal assistance from Gudrun Huden
and Judith Yonkers, who also provided the line drawings for
this book.
AUTHOR’S PREFACE
I also wish to acknowledge and thank the following for permission to quote: Harcourt, Brace & World for Antoine de
St. Exupery’s Flight to Arras and Night Flight; Harper &
Row for Mark Twain’s Captain Stormfield’s Visit to Heaven;
Houghton Mifflin for James J. Gibson’s The Perception of
the Visual World; Alfred A. Knopf, Inc., for Franz Kafka’s
The Trial and for Yasunari Kawabata’s Snow Country,
UNESCO Series of Contemporary Works (Japanese Series),
translated by Edward G. Seidensticker; Language for Edward
Sapir’s “The Status of Linguistics as a Science”; Massachusetts Institute of Technology for Benjamin Lee Whorfs Science and Linguistics; The Technology Press and John Wiley
& Sons for Benjamin Lee Whorfs Language, Thought, and
Reality; the University of Toronto Press for Edmund Carpenter’s Eskimo; and The Yale Review, Yale University Press
for Edward S. Deevey’s “The Hare and the Haruspex: A Cautionary Tale.”
Some of the material in Chapter X appeared previously in
my article titled “Silent Assumptions in Social Communication,” published in the proceedings of the Association for Research in Nervous and Mental Disease. Permission to use this
material is gratefully acknowledged.
I
CULTURE AS COMMUNICATION
The central theme of this book is social and personal space
and man’s perception of it. Proxemics is the term I have coined
for the interrelated observations and theories of man’s use of
space as a specialized elaboration of culture.
The concepts developed here did not originate with me.
Over fifty-three years ago, Franz Boas laid the foundation of
the view which I hold that communication constitutes the core
of culture and indeed of life itself. In the twenty years that
followed, Boas and two other anthropologists, Edward Sapir
and Leonard Bloomfield, speakers of the Indo-European languages, were confronted with the radically different languages
of the American Indians and the Eskimos. The conflict between these two different language systems produced a revolution concerning the nature of language itself. Before this
time, European scholars had taken Indo-European languages
as the models for all languages. Boas and his followers discovered in effect that each language family is a law unto itself,
a closed system, whose patterns the linguist must reveal and
describe. It was necessary for the linguistic scientist to consciously avoid the trap of projecting the hidden rules of his
own language on to the language being studied.
In the 1930s Benjamin Lee Whorf, a full-time chemist and
engineer but an amateur in the field of linguistics, began
studying with Sapir. Whorf s papers based on his work with
the Hopi and Shawnee Indians had revolutionary implications
for the relation of language to both thought and perception.
Language, he said, is more than just a medium for expressing
thought. It is, in fact, a major element in the formation of
thought. Furthermore, to use a figure from our own day, man’s
very perception of the world about him is programmed by
3
THE HIDDEN DIMENSION
CULTURE AS COMMUNICATION
the language he speaks, just as a computer is programmed.
Like the computer, man’s mind will register and structure
external reality only in accordance with the program. Since
two languages often program the same class of events quite
differently, no belief or philosophical system should be considered apart from language.
Only in recent years, and to just a handful of people, have
the implications of Whorf s thinking become apparent. Difficult to grasp, they became somewhat frightening when given
careful thought. They strike at the root of the doctrine of
“free will,” because they indicate that all men are captives of
the language they speak as long as they take their language
for granted.
The thesis of this book and of The Silent Language, which
preceded it, is that the principles laid down by Whorf and
his fellow linguists in relation to language apply to the rest of
human behavior as well—in fact, to all culture. It has long
been believed that experience is what all men share, that it
is always possible somehow to bypass language and culture
and to refer back to experience in order to reach another human being. This implicit (and often explicit) belief concerning man’s relation to experience was based on the assumptions
that, when two human beings are subject to the same “experience,” virtually the same data are being fed to the two central
nervous systems and that the two brains record similarly.
Proxemic research casts serious doubt on the validity of this
assumption, particularly when the cultures are different. Chapters X and XI describe how people from different cultures
not only speak different languages but, what is possibly more
important, inhabit different sensory worlds. Selective screening of sensory data admits some things while filtering out
others, so that experience as it is perceived through one set
of culturally patterned sensory screens is quite different from
experience perceived through another. The architectural and
urban environments that people create are expressions of this
filtering-screening process. In fact, from these man-altered
environments, it is possible to learn how different peoples use
their senses. Experience, therefore, cannot be counted on as
a stable point of reference, because it occurs in a setting that
has been molded by man.
The role of the senses in this context is described in Chapters IV through VII. This discussion was included to give the
reader some of the basic data on the apparatus man uses in
building his perceptual world. Describing the senses in this
way is analogous to descriptions of the vocal apparatus as a
basis for understanding speech processes.
An examination of how the senses are used by different
peoples, as they interact with their living and non-living environment, provides concrete data on some of the differences
between, for example, Arabs and Americans. Here at the very
source of the interaction it is possible to detect significant
variations in what is attended and what is screened out.
My research of the past five years demonstrates that
Americans and Arabs live in different sensory worlds much of
the time and do not use the same senses even to establish most
of the distances maintained during conversations. As we shall
see later, Arabs make more use of olfaction and touch than
Americans. They interpret their sensory data differently and
combine them in different ways. Apparently, even the Arab’s
experience of the body in its relation to the ego is different
from our own. American women who have married Arabs in
this country and who have known only the learned American
side of their personality have often observed that their husbands assume different personalities when they return to their
homelands where they are again immersed in Arab communication and are captives of Arab perceptions. They become
in every sense of the word quite different people.
In spite of the fact that cultural systems pattern behavior
in radically different ways, they are deeply rooted in biology
and physiology. Man is an organism with a wonderful and
extraordinary past. He is distinguished from the other animals
by virtue of the fact that he has elaborated what I have termed
extensions of his organism. By developing his extensions, man
has been able to improve or specialize various functions. The
computer is an extension of part of the brain, the telephone
extends the voice, the wheel extends the legs and feet. Language extends experience in time and space while writing extends language. Man has elaborated his extensions to such a
degree that we are apt to forget that his humanness is rooted
in his animal nature. The anthropologist Weston La Barre
4
5
THE HIDDEN DIMENSION
CULTURE AS COMMUNICATION
has pointed out that man has shifted evolution from his body
to his extensions and in so doing has tremendously accelerated
the evolutionary process.
Thus any attempt to observe, record, and analyze proxemic
systems, which are parts of modern cultures, must take into
account the behavioral systems on which they are based as
expressed by earlier life forms. Chapters II and III of this
book should help to provide both a foundation and a perspective to be used in considering the more complex human
elaborations of space behavior in animals. Much of the thinking and interpretation of data that went into this book has
been influenced by the tremendous strides made in recent
years by ethologists, the scientists who study animal behavior
and the relation of organisms to their environment.
In light of what is known of ethology, it may be profitable
in the long run if man is viewed as an organism that has
elaborated and specialized his extensions to such a degree that
they have taken over, and are rapidly replacing, nature. In
other words, man has created a new dimension, the cultural
dimension, of which proxemics is only a part. The relationship between man and the cultural dimension is one in which
both man and his environment participate in molding each
other. Man is now in the position of actually creating the
total world in which he lives, what the ethologists refer to as
his biotope. In creating this world he is actually determining
what kind of an organism he will be. This is a frightening
thought in view of how very little is known about man. It also
means that, in a very deep sense, our cities are creating different types of people in their slums, mental hospitals, prisons,
and suburbs. These subtle interactions make the problems of
urban renewal and the integration of minorities into the
dominant culture more difficult than is often anticipated.
Similarly, our lack of full understanding of the relation of
peoples and their biotope is compounding the process of technical development of the so-called underdeveloped nations
of the world.
ness. Recently it has become necessary to expand this view.
When people communicate they do much more than just toss
the conversational ball back and forth. My own studies as
well as those of others reveal a series of delicately controlled,
culturally conditioned servomechanisms that keeps life on an
even keel, much like the automatic pilot on the airplane. All
of us are sensitive to subtle changes in the demeanor of the
other person as he responds to what we are saying or doing.
In most situations people will at first unconsciously and later
consciously avoid escalation of what I have termed the
adumbrative or foreshadowing part of a communication from
the barely perceptible signs of annoyance to open hostility.
In the animal world, if the adumbrative process is shortcircuited or bypassed, vicious fighting is apt to occur. In humans in the international-intercultural sphere of life many
difficulties can be traced to failure to read adumbrations correctly. In such instances, by the time people discover what is
going on, they are so deeply involved that they can’t back out.
The following chapters include many instances of the
thwarting of communication primarily because neither of the
parties was aware that each inhabits a different perceptual
world. Each was also interpreting the other’s spoken words
in a context that included both behavior and setting, with a
result that positive reinforcement of friendly overtures was
often random or even absent.
Indeed, it is now believed by ethologists such as Konrad
Lorenz that aggression is a necessary ingredient of life; without it, life as we know it would probably not be possible.
Normally, aggression leads to proper spacing of animals, lest
they become so numerous as to destroy their environment and
themselves along with it. When crowding becomes too great
after population buildups, interactions intensify, leading to
greater and greater stress. As psychological and emotional
stress builds up and tempers wear thin, subtle but powerful
changes occur in the chemistry of the body. Births drop while
deaths progressively increase until a state known as population collapse occurs. Such cycles of buildup and collapse are
now generally recognized as normal for the warm-blooded
vertebrates and possibly for all life. Contrary to popular belief, the food supply is only indirectly involved in these cycles,
What happens when people of different cultures meet and
become involved? In The Silent Language I suggested that
communication occurs simultaneously on different levels of
consciousness, ranging from full awareness to out-of-aware-
6
THE HIDDEN DIMENSION
as demonstrated by John Christian and V. C. Wynne-Edwards.
As man developed culture he domesticated himself and in
the process created a whole new series of worlds, each different from the other. Each world has its own set of sensory
inputs, so that what crowds people of one culture does not
necessarily crowd another. Similarly, an act that releases aggression and would therefore be stressful to one people may
be neutral to the next. Nevertheless, it is fairly obvious that
the American Negroes and people of Spanish culture who are
flocking to our cities are being very seriously stressed. Not
only are they in a setting that does not fit them, but they have
passed the limits of their own tolerance to stress. The United
States is faced with the fact that two of its creative and sensitive peoples are in the process of being destroyed and like
Samson could bring down the structure that houses us all.
Thus it must be impressed upon architects, city planners, and
builders that if this country is to avoid catastrophe, we must
begin seeing man as an interlocutor with his environment, an
environment which these same planners, architects, and builders are now creating with little reference to man’s proxemic
needs.
To those of us who produce the income and pay the taxes
which support government, I say that whatever the cost of
rebuilding our cities, this cost will have to be met if America
is to survive. Most important, the rebuilding of our cities
must be based upon research which leads to an understanding of man’s needs and a knowledge of the many sensory
worlds of the different groups of people who inhabit American cities.
The chapters that follow are intended to convey a basic
message about the nature of man and his relationship to his
environment. The message is this:
There is a great need to revise and broaden our view of
the human situation, a need to be both more comprehensive
and more realistic, not only about others, but about ourselves
as well. It is essential that we learn to read the silent communications as easily as the printed and spoken ones. Only by
doing so can we also reach other people, both inside and
outside our national boundaries, as we are increasingly required to do.
II
DISTANCE REGULATION IN ANIMALS
Comparative studies of animals help to show how man’s
space requirements are influenced by his environment. In animals we can observe the direction, the rate, and the extent of
changes in behavior that follow changes in space available to
them as we can never hope to do in men. For one thing, by
using animals it is possible to accelerate time, since animal
generations are relatively short. A scientist can, in forty years,
observe four hundred forty generations of mice, while he has
in the same span of time seen only two generations of his
own kind. And, of course, he can be more detached about the
fate of animals.
In addition, animals don’t rationalize their behavior and
thus obscure issues. In their natural state, they respond in
an amazingly consistent manner so that it is possible to observe repeated and virtually identical performances. By restricting our observations to the way animals handle space,
it is possible to learn an amazing amount that is translatable
to human terms.
Territoriality, a basic concept in the study of animal behavior, is usually defined as behavior by which an organism
characteristically lays claim to an area and defends it against
members of its own species. It is a recent concept, first described by the English ornithologist H. E. Howard in his Territory in Bird Life, written in 1920. Howard stated the concept in some detail, though naturalists as far back as the
seventeenth century had taken note of various events which
Howard recognized as manifestations of territoriality.
Territoriality studies are already revising many of our basic
ideas of animal life and human life as well. The expression
“free as a bird” is an encapsulated form of man’s conception
9
THE HIDDEN DIMENSION
DISTANCE REGULATION IN ANIMALS
of his relation to nature. He sees animals as free to roam the
world, while he himself is imprisoned by society. Studies of
territoriality show that the reverse is closer to the truth and
that animals are often imprisoned in their own territories.
It is doubtful if Freud, had he known what is known today
about the relation of animals to space, could have attributed
man’s advances to trapped energy redirected by culturally imposed inhibitions.
Many important functions are
expressed in territoriality, and new
ones are constantly being discovered. H. Hediger, Zurich’s famous
animal psychologist, described the
most important aspects of territoriality and explained succinctly the
mechanisms by which it operates.
Territoriality, he says, insures the
propagation of the species by regulating density. It provides a frame
in which things are done—places to
learn, places to play, safe places to
hide. Thus it co-ordinates the activities of the group and holds the
group together. It keeps animals
within communicating distance of
each other, so that the presence of
food or an enemy can be signaled.
An animal with a territory of its
own can develop an inventory of
reflex responses to terrain features.
When danger strikes, the animal on
its home ground can take advantage
of automatic responses rather than
having to take time to think about
where to hide.
relating to the protection and evolution of the species. The
list that follows is not complete, nor is it representative of all
species, but it indicates the crucial nature of territoriality as
a behavioral system, a system that evolved in very much the
same way as anatomical systems evolved. In fact, differences
in territoriality have become so widely recognized that they
are used as a basis for distinguishing between species, much
as anatomical features are used.
Territoriality offers protection from predators, and also exposes to predation the unfit who are too weak to establish and
defend a territory. Thus, it reinforces dominance in selective breeding because the less dominant animals are less likely to establish
territories. On the other hand territoriality facilitates breeding by providing a home base that is safe. It
aids in protecting the nests and the
young in them. In some species it
localizes waste disposal and inhibits
or prevents parasites. Yet one of the most important functions
of territoriality is proper spacing, which protects against overexploitation of that part of the environment on which a species depends for its living.
In addition to preservation of the species and the environment, personal and social functions are associated with territoriality. C. R. Carpenter tested the relative roles of sexual
vigor and dominance in a territorial context and found that
even a desexed pigeon will in its own territory regularly win
a test encounter with a normal male, even though desexing
usually results in loss of position in a social hierarchy. Thus,
while dominant animals determine the general direction in
which the species develops, the fact that the subordinate can
win (and so breed) on his home grounds helps to preserve
plasticity in the species by increasing variety and thus preventing the dominant animals from freezing the direction
which evolution takes.
Territoriality is also associated with status. A series of experiments by the British ornithologist A. D. Bain on the
great tit altered and even reversed dominance relationships
The psychologist C. R. Carpenter, who pioneered in the observation of monkeys in a native setting,
listed thirty-two functions of territoriality, including important ones
10
THE HIDDEN DIMENSION
by shifting the position of feeding stations in relation to
birds living in adjacent areas. As the feeding station was
placed closer and closer to a bird’s home range, the bird
would accrue advantages it lacked when away from its own
home ground.
Man, too, has territoriality and he has invented many ways
of defending what he considers his own land, turf, or spread.
The removal of boundary markers
and trespass upon the property of
another man are punishable acts in
much of the Western world. A
man’s home has been his castle in
English common law for centuries,
and it is protected by prohibitions
on unlawful search and seizure even
by officials of his government. The
distinction is carefully made between private property, which
is the territory of an individual, and public property, which
is the territory of the group.
This cursory review of the functions of territoriality should
suffice to establish the fact that it is a basic behavioral system
characteristic of living organisms including man.
SPACING MECHANISMS IN ANIMALS
In addition to territory that is identified with a particular
plot of ground, each animal is surrounded by a series of bubbles or irregularly shaped balloons that serve to maintain
proper spacing between individuals. Hediger has identified and
described a number of such distances which appear to be
used in one form or another by most animals. Two of these
—flight distance and critical distance—are used when individuals of different species meet; whereas personal distance and
social distance can be observed during interactions between
members of the same species.
DISTANCE REGULATION IN ANIMALS
11
Flight Distance
Any observant person has noticed that a wild animal will
allow a man or other potential enemy to approach only up
to a given distance before it flees. “Flight distance” is Hediger’s
term for this interspecies spacing mechanism. As a general
rule, there is a positive correlation between the size of an animal and its flight distance—the larger the animal, the greater
the distance it must keep between itself and the enemy. An
antelope will flee when the intruder is as much as five hundred yards away. The wall lizard’s flight distance, on the other
hand, is about six feet.
There are, of course, other ways of coping with a predator,
such as camouflage, protective armor or spines, or offensive
odor. But flight is the basic mechanism of survival for mobile
creatures. In domesticating other animals, man has had to
eliminate or radically reduce the flight reaction. In zoos, it is
essential to modify the flight reaction enough so that the captive animal can move about, sleep, and eat without being
panicked by man.
Although man is a self-domesticated animal, the domestication process is only partial. We see this in certain types of
schizophrenics who apparently experience something very
similar to the flight reaction. When approached too closely,
these schizophrenics panic in much the same way as an animal recently locked up in a zoo. In describing their feelings,
such patients refer to anything that happens within their “flight
distance” as taking place literally inside themselves. That is,
the boundaries of the self extend beyond the body. These
experiences recorded by therapists working with schizophren-
12
THE HIDDEN DIMENSION
ics indicate that the realization of the self as we know it is
intimately associated with the process of making boundaries
explicit. This same relationship between boundaries and self
can also be observed in cross-cultural contexts, as we shall
see in Chapter XI.
Critical Distance
Critical distances or zones apparently are present wherever and
whenever there is a flight reaction.
“Critical distance” encompasses the
narrow zone separating flight distance from attack distance. A lion
in a zoo will flee from an approaching man until it meets an insurmountable barrier. If the man comtinues the approach, he soon penetrates the lion’s critical distance, at
which point the cornered lion reverses direction and begins slowly
to stalk the man.
In the classical animal act in the
circus, the lion’s stalking is so deliberate that he will surmount an
intervening obstacle such as a stool
in order to get at the man. To get
the lion to remain on the stool, the
lion tamer quickly steps out of
the critical zone. At this point, the
lion stops pursuing. The trainer’s
elaborate “protective” devices—the
chair, the whip, or the gun—are so
much window dressing. Hediger
says the critical distance for the
animals he has knowledge of is so
precise that it can be measured in centimeters.
DISTANCE REGULATION IN ANIMALS
13
Contact and Non-Contact Species
In regard to the use of space, it is possible to observe a
basic and sometimes inexplicable dichotomy in the animal
world. Some species huddle together and require physical
contact with each other. Others completely avoid touching.
No apparent logic governs the category into which a species
falls. Contact creatures include the walrus, the hippopotamus,
the pig, the brown bat, the parakeet, and the hedgehog among
many other species. The horse, the dog, the cat, the rat, the
muskrat, the hawk, and the blackheaded gull are non-contact
species. Curiously enough, closely related animals may belong
to different categories. The great Emperor penguin is a contact species. It conserves heat through contact with its fellows
by huddling together in large groups and thus increases its
adaptability to cold. Its range extends over many parts of
Antarctica. The smaller Adelie penguin is a non-contact species. Thus it is somewhat less adaptable to cold than the
Emperor, and its range is apparently more limited.
What other functions may be served by contact behavior
are unknown. One could hazard a guess that, since contact
animals are more “involved” with each other, their social
organization and possibly their manner of exploiting the environment might be different from those of non-contact animals. Non-contact species, one would think, would be more
vulnerable to the stresses exerted by crowding. It is clear that
all warm-blooded animals begin life in the contact phase.
This phase is only temporary with the many non-contact
species, for the young abandon it as soon as they leave their
parents and are on their own. From this point in the life cycle
of both types, regular spacing between individuals can be observed.
Personal Distance
Personal distance is the term applied by Hediger to the
normal spacing that non-contact animals maintain between
themselves and their fellows. This distance acts as an invisible
bubble that surrounds the organism. Outside the bubble two
15
THE HIDDEN DIMENSION
DISTANCE REGULATION IN ANIMALS
organisms are not as intimately involved with each other as
when the bubbles overlap. Social organization is a factor in
personal distance. Dominant animals tend to have larger personal distances than those which occupy lower positions in
the social hierarchy, while subordinate animals have been observed to yield room to dominant ones. Glen McBride, an
Australian professor of animal husbandry, has made detailed
observations of the spacing of domestic fowl as a function
of dominance. His theory of “social organization and behavior” has as a main element the handling of space. This correlation of personal distance and status in one form or another seems to occur throughout the vertebrate kingdom. It
has been reported for birds and many mammals, including
the colony of ground-living Old World monkeys at the
Japanese Monkey Center near Nagoya.
Aggression is an essential component in the make-up of
vertebrates. A strong, aggressive animal can eliminate weaker
rivals. There seems to be a relation between aggression and
display so that the more aggressive animals display more
vigorously. In this way, too, display and aggression serve as
handmaidens in the process of natural selection. To insure
survival of the species, however, aggression must be regulated. This can be done in two ways: by development of
hierarchies and by spacing. Ethologists seem to agree that
spacing is the more primitive method, not only because it is
the simplest but because it is less flexible.
quite long among some other birds. The late E. Thomas
Gilliard, an American ornithologist, tells how clans of male
bowerbirds maintain contact “over many thousands of feet
by means of mighty whistles and harsh, rasping notes.”
Social distance is not always rigidly fixed but is determined
in part by the situation. When the young of apes and humans
are mobile but not yet under control of the mother’s voice,
social distance may be the length of her reach. This is readily
observed among the baboons in a zoo. When the baby approaches a certain point, the mother reaches out to seize the
end of its tail and pull it back to her. When added control is
needed because of danger, social distance shrinks. To document this in man, one has only to watch a family with a number of small children holding hands as they cross a busy
street.
Social distance in man has been extended by telephone,
TV, and the walkie-talkie, making it possible to integrate the
activities of groups over great distances. Increased social distance is now remaking social and political institutions in
ways that have only recently begun to be studied.
14
Social Distance
Social animals need to stay in touch with each other. Loss
of contact with the group can be fatal for a variety of reasons
including exposure to predators. Social distance is not simply
the distance at which an animal will lose contact with his
group—that is, the distance at which it can no longer see,
hear, or smell the group—it is rather a psychological distance,
one at which the animal apparently begins to feel anxious
when he exceeds its limits. We can think of it as a hidden
band that contains the group.
Social distance varies from species to species. It is quite
short—apparently only a few yards—among flamingos, and
POPULATION CONTROL
In the cold waters of the North Sea lives a form of crab,
Hyas araneus. The distinguishing feature of the species is that,
at certain times in the life cycle, the individual becomes vulnerable to others of the same species, and some are sacrificed
to keep the population down. Periodically, when the crab
sheds its shell, its only protection is the space that separates
it from crabs in the hard-shell stage. Once a hard-shelled
crab gets close enough to scent his soft-shelled fellow—that
is, once the olfactory boundary is passed—smell leads the
hard-shelled predator to his next meal.
Hyas araneus provides us with an example of both a “critical
space” and a “critical situation.” These terms were originally
used by Wilhelm Schafer, Director of the Frankfurt Natural
History Museum. Schafer, in an attempt to understand basic
life processes, was one of the first to examine the ways in
which organisms handle space. His 1956 study was unique
THE HIDDEN DIMENSION
DISTANCE REGULATION IN ANIMALS
in directing attention to crises of survival. Animal societies,
he stated, build up until a critical density is reached, thus
creating a crisis that must be met if the society is to survive.
Schafer’s important contribution was to classify crises of survival and find a pattern in the various ways which simple
forms of life have worked out to deal with the crowding that
brings on such crises. Schafer analyzed the process that
relates population control to the solution of other important
life problems.
As we have already seen, all animals have a minimum
space requirement, without which survival is impossible. This
is the “critical space” of the organism. When the population
has built up so greatly that the critical space is no longer
available, a “critical situation” develops. The simplest way of
handling the situation is to remove some individuals. This can
be accomplished in a variety of
ways, one of which is illustrated by
Hyas araneus.
Crabs are solitary animals. At
the time in the life cycle when they
must locate other crabs in order to
reproduce, they find each other by
smell. Thus the survival of the species depends on not having individuals roam so far apart that they
cannot smell each other. But the
critical space crabs need is also
well defined. When their numbers
increase to the point where critical
space is not available, enough of
those individuals who are in the
soft-shell stage are eaten to bring
the population back to a level at
which individuals have enough room.
waters in Europe. The stickleback was made famous when
the Dutch ethologist Niko Tinbergen identified the complex
sequence the fish has developed to reproduce itself. Tinbergen
later showed that a short-circuiting of the sequence results
in a population decrease.
In the spring, each male stickleback carves out a circular
territory, defends it several times against all comers, and
builds a nest. His inconspicuous gray coloring then changes,
so that his chin and belly are bright red, his back blue-white,
and his eyes blue. The change in coloration serves to attract
females and repel males.
When a female, her belly swollen with eggs, comes within
range of the stickleback’s nest, the male zigzags toward her,
alternately displaying his face and colorful profile. The twostep approach ceremony must be repeated several times before
the female will follow the male and enter the nest Shifting
from the visual mode of communication to the more basic
one of touch, the male with his nose rhythmically prods the
female at the base of her spine until she lays her eggs. The
male then enters the nest, fertilizes the eggs, and drives the
female away. He repeats this sequence until four or five females have deposited eggs in his nest.
At this point the mating impulse subsides, and a new set
of responses is observed. The male becomes his old inconspicuous gray. His role now is to defend the nest and keep
the eggs supplied with oxygen by fanning water through the
nest with his pectoral fins. When the eggs hatch, the male
protects the young fish until they are big enough to fend for
themselves. He will even catch those that wander too far,
carrying them in his mouth carefully back to the nest
The stickleback’s behavior sequence—including fighting,
mating, and caring for the young—is so predictable that Tinbergen was able to conduct a series of experiments which
provides valuable insights into the message systems or signals that release responses to the different drives. The male’s
zigzag approach to the female is a response to an urge to
attack, which has to run its course before the sexual urge
takes over. The swollen shape of the egg-heavy female releases
the courting response in the male. After she has laid her eggs,
red no longer attracts her. She will not lay eggs until she
16
THE STICKLEBACK SEQUENCE
Several notches above the crab on the evolutionary scale is
the stickleback, a small fish that is common in shallow fresh
18
19
THE HIDDEN DIMENSION
DISTANCE REGULATION IN ANIMALS
has been prodded by the male. Thus, vision and touch trigger
the several elements of the sequence.
The predictable nature of the sequence enabled Tinbergen
to observe in experimental situations what happens when the
sequence is interrupted by the presence of too many males
and consequent crowding of individual territories. The red of
too many males disrupts courting. Some steps in the sequence
are omitted so that eggs are not laid in a nest or fertilized.
Under very crowded conditions, males will battle each other
until some are killed.
to suspect that there was more to population control than
predators and food supply and that the behavior of lemmings
and rabbits might bear on these other factors. At the time of
large-scale die-offs, there appeared to be plenty of food available, and carcasses showed no signs of starvation.
Among the scientists studying this phenomenon was John
Christian, an ethologist with training in medical pathology.
In 1950 he advanced the thesis that increase and decrease in
mammalian populations are controlled by physiological mechanisms that respond to density. He presented evidence showing that as numbers of animals in a given area increase, stress
builds up until it triggers an endocrine reaction that acts to
collapse the population.
Christian needed more data and had been looking for a
chance to study a mammalian population in the actual process of collapsing. The ideal situation would be one in which
endocrine studies could be made before, during, and after
collapse. Fortunately, the buildup of the population of the
James Island deer came to his attention before it was too late.
MALTHUS RECONSIDERED
The crab and the stickleback provide useful information
about the relation of space to reproduction and population
control. The crab’s sense of smell is the key to distance required by the individual and determines the maximum number of crabs that can inhabit a given area of the sea. In the
stickleback, sight and touch set off an ordered sequence that
must run its course if the fish is to reproduce. Crowding disrupts this sequence and thus interferes with reproduction. In
both animals acuity of the receptors—smell, sight, touch, or a
combination—determines the distance at which individuals can
live and continue to perform the reproduction cycle. Without
proper maintenance of this distance, they lose the battle to
one of their own kind, rather than to starvation, disease, or a
predator.
There is a growing need for reconsideration of the Malthusian doctrine which relates population to the food supply. For
centuries, Scandinavians have watched the march of the lemmings to the sea. Similar suicidal activities have been observed
among rabbits at the time of large-scale population buildups
followed by die-off. Natives of certain Pacific islands have
seen rats doing the same sort of thing. This weird behavior
on the part of certain animals has led to every imaginable
explanation, yet it wasn’t until recently that some insight was
gained as to the factors that lay behind the lemmings’ mad
dash.
About the time of World War II, a few scientists began
THE DIE-OFF ON JAMES ISLAND
About fourteen miles west of the town of Cambridge,
Maryland, and less than a mile out in Chesapeake Bay lies
James Island, approximately half a square mile (280 acres)
of uninhabited land. In 1916 four or five Sika deer (Cervus
nippon) were released on the island. Breeding freely, the
herd built up steadily until it numbered between 280 and 300,
a density of about one deer per acre. At this point, reached
in 1955, it was apparent that something would have to give
before too long.
In 1955, Christian began his research by shooting five deer
for detailed histological studies of the adrenal glands, thymus,
spleen, thyroid, gonads, kidneys, liver, heart, lungs, and other
tissues. The deer were weighed, the contents of their stomachs
recorded, and age, sex, and general condition, as well as the
presence or absence of deposits of fat under the skin, in the
abdomen, and between the muscles, were noted.
Once these records were made, the observers settled down
20
21
THE HIDDEN DIMENSION
DISTANCE REGULATION IN ANIMALS
to wait. In 1956 and 1957 no change occurred. But in the first
three months of 1958, over half of the deer died, and 161 carcasses were recovered. The following year more deer died and
another drop took place. The population stabilized at around
eighty. Twelve deer were collected for histological study between March 1958 and March 1960.
What was responsible for the sudden death of one hundred
ninety deer in a two-year period? It wasn’t starvation, because
the food supply was adequate. In fact, all of the deer collected
were in excellent condition, with shining coats, well-developed
muscles, and fat deposits between the muscles.
Carcasses collected between 1959 and 1960 resembled
those taken in 1956 and 1957 in every outward respect but
one. The deer taken after the population collapse and stabilization were markedly larger in body size than those taken
just before and during the die-off. The 1960 bucks averaged
34 per cent heavier than the 1958 bucks. Does taken in 1960
were 28 per cent heavier than the 1955-57 does.
The weight of the adrenal glands of the Sika deer remained
constant from 1955 to 1958, during the period of maximum
density and die-off. The weight decreased 46 per cent between 1958 and 1960. In immature deer, who formed a large
proportion of the casualties, adrenal weight dropped 81 per
cent after the die-off. There were also important changes in
the cell structure of the adrenals that pointed to great stress,
even in the survivors. While two cases of hepatitis were discovered, it was thought that these were a result of decreased
resistance to stress due to overactive adrenals. In interpreting
Christian’s data, it is important to clarify the significance of
the adrenal glands. The adrenals play an important part in
the regulation of growth, reproduction, and the level of the
body’s defenses. The size and weight of these important glands
is not fixed but responds to stress. When animals are too frequently stressed, the adrenals, in order to meet the emergency,
become overactive and enlarged. The enlarged adrenals of
characteristic cell structure showing stress were therefore
highly significant.
An added factor which undoubtedly contributed to stress
was the fact that freezing weather in February of 1958 prevented the deer from swimming to the mainland at night, as
was their custom, a journey which afforded at least temporary
respite from crowding. The major die-off followed this freeze.
Lack of relief from confinement, combined with cold, which
is also known to cause stress, may have been the last straw.
Summing up at a symposium on crowding, stress, and natural selection in 1961, Christian stated: “Mortality evidently
resulted from shock following severe metabolic disturbance,
probably as a result of prolonged adrenocortical hyperactivity,
judging from the histological material. There was no evidence
of infection, starvation, or other obvious cause to explain the
mass mortality.”
From the physiological side, Christian’s study is complete
and leaves nothing to be desired. There are, however, some
questions about the behavior of the deer under stress that
will remain unanswered until another opportunity presents
itself. For example, did they show increased aggression? Was
this one reason why about nine-tenths of the casualties during
the die-off were does and fawns? Hopefully, it will be possible
to have a year-round observer next time.
PREDATION AND POPULATION
Less dramatic, but useful in supplying additional evidence
that the Malthusian doctrine cannot account for the majority
of mass die-offs, were the late Paul Errington’s investigations
of predation. Errington found, on examining the stomach contents of owls, that a very high proportion consisted of young,
immature, old, or sick animals (which were too slow to escape the predator). In a study of muskrats, he found that
more died of disease, apparently as a consequence of lowered
resistance due to stress from overcrowding, than were captured by the voracious mink. Twice in one year, muskrats
dead of disease were found in one lodge. Errington states that
muskrats share with men the propensity of growing savage
under stress from crowding. He also shows that crowding past
a certain limit results in lowered birth rates for muskrats.
By now, many ethologists have on their own come to the
conclusion that the relationship of the predator to his prey
is one of subtle symbiosis in which the predator does not con-
22
THE HIDDEN DIMENSION
trol population but is rather a constant environmental pressure
that acts to improve the species. Interestingly enough, little
attention is paid to these studies. A recent example has been
described in detail by the biologist Farley Mowat, who was
sent to the Arctic by the Canadian government to establish
the number of caribou killed by wolves. The caribou herds
have been dwindling so that the wolves could be exterminated
in clear conscience. He found that: (a) the wolves accounted
for only a small number of caribou deaths; (b) they were
important to the caribou in keeping the herds healthy and
strong (a fact which the Eskimo knew all along); and (c)
it was the killing of caribou by hunters and trappers to feed
their dogs in the winter which was decreasing the herds. In
spite of the convincing, carefully marshaled evidence which
appears in his book, Never Cry Wolf, wolves are now being
systematically poisoned, according to Mowat. While it is not
possible to calculate in advance what the loss of the Arctic
wolf will mean, the lesson should not be ignored. This is simply one of the many examples of how shortsighted cupidity
can threaten the balance of nature. When the wolves are
gone, the caribou will continue to decrease because the hunters
will be there. Those that remain will not be kept as strong as
before due to removal of the therapeutic pressure formerly
provided by the wolves.
The above examples fall into the general category of the
natural experiment. What happens when an element of control is introduced and populations of animals are allowed to
build up freely with plenty of food but in the absence of
predators? The experiments and studies described in the next
chapter reveal quite clearly that predation and food supply
may be less significant than we think. They document in
detail the role of stress from crowding as a factor in population control and provide some insights into the biochemical
mechanisms of population control.
HI
CROWDING AND SOCIAL BEHAVIOR
IN ANIMALS
CALHOUN’S EXPERIMENTS
Anyone driving along a country road outside Rockville,
Maryland, in 1958 would hardly have noticed an ordinary
stone barn set back from the road. Inside it was far from
ordinary, however, for it housed a structure set up by the
ethologist John Calhoun to provide for the material needs of
several colonies of domesticated white Norway rats. Calhoun
wished to create a situation in which it would be possible to
observe the behavior of the rat colonies at any time.
Actually, the experiments in the barn represented only the
most recent phase of a fourteen-year research program. In
March 1947, Calhoun initiated his studies of population
dynamics under natural conditions by introducing five pregnant wild Norway rats into a quarter-acre outdoor pen. His
observations covered twenty-eight months. Even with plenty
of food and no pressure from predation, the population never
exceeded 200 individuals, and stabilized at 150. The difference
between experiments carried out in the laboratory and what
happens to wild rats living under more natural conditions is
emphasized by these studies. Calhoun makes the point that
in the twenty-eight months covered by the study the five
female rats could have produced 50,000 progeny. Yet available
space could not have accommodated this number. Nevertheless 5000 rats can be kept in a healthy state in 10,000 square
feet of space if they are kept in pens two feet square. If the
cage size is reduced to eight inches, the 50,000 rats can not
only be accommodated but remain healthy. The question
THE HIDDEN DIMENSION
CROWDING AND SOCIAL BEHAVIOR IN ANIMALS
Calhoun posed was, Why did the population level off at 150
in the wild state?
Calhoun discovered that even with 150 rats in a quarteracre pen fighting was so disruptive to normal maternal care
that only a few of the young survived. Furthermore, the rats
were not randomly scattered throughout the area, but had
organized themselves into twelve or thirteen discrete local
colonies of a dozen rats each. He also noted that twelve rats
is the maximum number that can live harmoniously in a natural group and that even this number may induce stress with
all the physiological side effects described at the end of
Chapter II.
The experience gained with the outdoor pen enabled Calhoun to design a set of experiments in which rat populations
could build up freely under conditions that would permit detailed observation without influencing the behavior of the rats
in relation to each other.
The results of these experiments are sufficiently startling to
warrant a detailed description. Alone, they tell us a great
deal about how organisms behave under different conditions
of crowding, and they throw new light on how the social behavior that accompanies crowding can have significant physiological consequences. Combined with Christian’s work mentioned earlier and with hundreds of other experiments and
observations on animals ranging from weasels and mice to
humans, Calhoun’s studies take on added significance.
Calhoun’s experiments are unusual because psychologists
conducting this type of research traditionally attempt to control or eliminate all except one or two variables which they
can then manipulate at will. Also most of their research applies to the responses of individual organisms. Calhoun’s experiments, however, dealt with large, reasonably complex
groups. By choosing subjects with a short life span, he was
able to correct a defect common to group behavior studies
—that they usually cover too little time, and thus fail to show
the accumulation effect of a given set of circumstances on
several generations. Calhoun’s methods were in the best tradition of science. Not content with simply one or two sixteenmonth runs in which the population was allowed to build up,
he ran six, beginning in 1958 and ending in 1961. The findings
of these studies are so varied and so broad in their implications that it is difficult to do justice to them. They should continue to produce new insight for years to come.
24
25
Design of the Experiment
Inside his Rockville barn, Calhoun built, three 10 by 14foot rooms open to observation through 3 by 5-foot glass
windows cut in the floor of the hayloft. This arrangement
permitted observers to have a complete view of the lighted
room at any time of the day or night without disturbing the
rat. Each room was divided into four pens by electrified
partitions. Each pen was a complete dwelling unit, containing
a food hopper, a drinking trough, places to nest (skyscraper
type burrows for observation), and nesting materials. Ramps
over the electrified fence connected all pens but I and IV.
These areas then became the end pens of a row of four that
had been folded to save space.
The experience with the wild rats had indicated that forty
to forty-eight rats could occupy the room. If they were
equally divided, each pen would accommodate a colony of
twelve rats, the maximum number of a normal group before
serious stress from crowding occurs.
To begin bis studies, Calhoun placed one or two pregnant
females about to give birth in each pen with ramps removed,
and allowed the young to mature. A balanced sex ratio was
maintained by removing the excess so that his first series began
with thirty-two rats, offspring of the five females. Then ramps
were replaced and all rats were allowed complete freedom to
explore all four pens. The second series began with fifty-six
rats, and the mothers were removed upon weaning their
young. As in the first series, the connecting ramps were replaced so that the young mature rats could explore all four
pens.
From this point on, human intervention ceased except for
the removal of surplus infants. This was done in order to prevent the population from exceeding a limit of eighty, twice
that at which stress was definitely detectable. Calhoun rea-
26
THE HIDDEN DIMENSION
soned that if he failed to maintain this safety margin, the
colonies would suffer a population collapse, or die-off, similar
to that of the Sika deer, from which they would not recover.
His strategy was to maintain a population in a stressful situation while three generations of rats were reared, so that he
could study the effects of stress not only on individuals but
on several generations.
Development of the Sink
The word “sink” is used figuratively to mean a receptacle
of foul or waste things. Calhoun invented the term “behavioral
sink” to designate the gross distortions of behavior which
appeared among the majority of the rats in the Rockville
barn. Such a phenomenon, he believes, is “the outcome of
any behavioral process that collects animals together in
unusually great numbers. The unhealthy connotations of the
term are not accidental: a behavioral sink does act to aggravate all forms of pathology that can be found within a
group.”
The behavioral sink included disruptions of nest building,
courting, sex behavior, reproduction, and social organization.
Autopsied rats showed serious physiological effects as well.
The sink was reached when the population density was
approximately double that which had been observed to produce a maximum of stress in the wild rat colony. The term
“density” must be expanded beyond simple ratio of individuals to available space. Except in the most extreme cases,
density alone seldom causes stress in animals.
In order to grasp Calhoun’s idea, we need to move for the
moment to the young rats and follow them from the time they
were given freedom to roam the four pens to the time when
the sink developed. In the normal uncrowded state, there is a
short period when the young but physically mature male rats
fight with each other until they establish a fairly stable social
hierarchy. In the first of the two Rockville series described
here, two dominant male rats established territories in Pens
I and IV. Each maintained a harem of eight to ten females,
so that his colony was balanced and consistent with the natu-
CROWDING AND SOCIAL BEHAVIOR IN ANIMALS
27
ral grouping among rats as observed in the
quarter-acre pen. The remaining fourteen
male rats distributed themselves in Pens II
and IIL As the population built up to sixty
or more, the chances of a rat’s being able to
eat by himself were minimal. This was because food hoppers had been so designed that
food pellets behind a wire screen took a ”
long time to extract. The rats in Pens II and
III became conditioned, therefore, to eating
with other rats. Calhoun’s observations re- w
vealed that when activity built up in the
middle pens so that the food hoppers were
used from three to five times more frequently jy
than the end pens, the sink began to develop.
Normal patterns of behavior were disrupted as follows.
Courting and Sex
Courting and sex in the Norway rat normally involve a
fixed sequence of events. Male rats have to be able to make
three basic distinctions in the selection of a mate. First, they
have to make the usual male-female distinction and be able
to tell the difference between mature and immature individuals. Then they must find a female in a receptive (oestrous)
state. When this combination appears within his visual and
olfactory field, the male rat chases the female. She runs, but
not too fast, and ducks down into the burrow, turns around
and sticks her head up to watch the male. He runs around the
opening of the burrow and performs a little dance. When
the dance is over, the female leaves the burrow and mounting
takes place. During the sex act, the male will grasp the skin
on the female’s neck gently between his teeth.
When the sink developed in Pens II and III, everything
changed. Several different categories of males could be
identified:
1. The aggressively dominant, of whom there might be as
many as three, exhibited normal behavior.
2. The passive males avoided both fighting and sex.
THE HIDDEN DIMENSION
CROWDING AND SOCIAL BEHAVIOR IN ANIMALS
3. The hyperactive subordinate males spent their time chasing females. Three or four might be tailing one harassed female at the same time. During the pursuit phase, they would
fail to observe the amenities; instead of stopping at the “burrow” entrance they would follow the female inside so that
she had no respite. During mounting, these male rats frequently maintained their grasp on females for several minutes instead of the usual two or three seconds.
4. Pansexual males tried mounting anything; receptive and
non-receptive females, males and females alike, young and
old. Any sex partner would do.
5. Some males withdrew from social and sexual intercourse
and went abroad chiefly at the time when other rats slept.
young but would fail to complete some phase of the move.
Young carried outside to another nest were often dropped and
eaten by other rats.
28
Nest Building
Both male and female rats participate in building but the
female does most of the work. Nesting material is carried into
the burrow, piled up, and hollowed out to form a cavity to
hold the young. In the Rockville study, females from the
“harems” in Pens I and IV and others who had not reached
the sink stage were “good housekeepers”; they were neat and
kept the area around the nest picked up. Sink females in II
and III often failed to complete the nest. They could be seen
carrying a piece of nesting material up a ramp and suddenly
dropping it. Material that reached the nest was either dropped
in the general area or added to a pile that was never hollowed
out, so that the young became scattered at birth and few
survived.
Care of the Young
Normally, females work hard to keep litters sorted out and
if a strange pup was introduced into the nest, the female
would remove it. When nests were uncovered, the young
would be moved to a new location that was more protected.
Sink mothers in the Rockville study failed to sort out the
young. Litters became mixed; the young were stepped on
and often eaten by hyperactive males who invaded the nests.
When a nest was exposed, the mother would start moving the
29
Territoriality and Social Organization
The Norway rat has evolved a simple social organizational
pattern that calls for living in groups of ten to twelve hierarchically graded individuals occupying a common territory
which they defend. The group is dominated by one mature
male and is made up of varying proportions of both sexes.
High-ranking rats do not have to defer to other rats as much
as low-ranking rats. Their status is indicated in part by those
areas within the territory which are open to them. The higher
the status, the greater the number of areas they may visit.
Doininant male rats in the sink, mnable to establish territories, substituted time for space. Three times daily there
was a tempestuous “changing of the guard” around the eating bins that was characterized by fighting and scuffling.
Each group was dominated by a single male. These three
males were equal to each other in rank, but unlike normal
hierarchies, which are extraordinarily stable in nature, social
rank in the sink was very unstable. “At regular intervals
during the course of their working hours, these top-ranking
males engaged in free-for-alls that culminated in the transfer
of dominance from one male to another.”
Another social manifestation was what Calhoun called
“classes” of rats, which shared territories and exhibited similar
behavior. The function of the class, apparently, is to reduce
friction between the rats. Normally, there were as many as
three classes in a colony.
An increase in population density leads to a proliferation
of classes and subclasses. The hyperactive males violated not
only the mating mores by invading the burrow when chasing
females, but other territorial mores as well. They ran around
in a pack, pushing, probing, exploring, testing. Apparently
they were afraid only of the dominant male sleeping at the
foot of the ramp in the Pen I or IV area, protecting his territory and his harem against all comers.
The advantages to both the species and the individual be-
THE HIDDEN DIMENSION
CROWDING AND SOCIAL BEHAVIOR IN ANIMALS
stowed by territoriality and stable hierarchical relationships
were clearly demonstrated by the rats who occupied Pen I.
From the observation window in the top of the room, one
could look down and see a large, healthy rat asleep at the
foot of a ramp. At the top of the ramp, a small group of
hyperactive males might be testing him to see if they could
enter. He needed only to open an eye to discourage invasion.
From time to time, one of the females would emerge from
a burrow, cross in front of the sleeping male, scamper up
the ramp without awakening him, and return later, followed
by a pack of hyperactive males who would stop when they
reached the top of the ramp. Beyond this point she would
not be molested and could bear and rear her young undisturbed by the constant turmoil of the sink. Her measured
record of achievement as a mother was ten to twenty-five
times that of females in the sink. Not only did she bear twice
as many young, but half or better of her young would survive weaning.
very extensive, often unprovoked and unpredictable tail biting. This behavior went on for about three months, until the
mature rats discovered new ways to suppress tail biting in
their fellows. But young rats, who had not learned how to
keep their tails from being bitten, were still subject to extensive damage.
30
Physiological Consequences
of
the
Sink
As with the Sika deer, the sink hit hardest at the female
rats and the young. The mortality rate of females in the sink
was three and a half times that of the males. Of the 558
young born at the height of the sink, only one-fourth survived
to be weaned. Pregnant rats had trouble continuing pregnancy.
Not only did the rate of miscarriages increase significantly,
but the females started dying from disorders of the uterus,
ovaries, and fallopian tubes. Tumors of the mammary glands
and sex organs were identified in autopsied rats. The kidneys,
livers, and adrenals were also enlarged or diseased and
showed signs that are usually associated with extreme stress.
Aggressive
Behavior
As Konrad Lorenz, the German ethologist, has made clear
in Man Meets Dog, normal aggressive behavior has accompanying signals that will extinguish the aggressive impulse
when the vanquished has “had enough.” Male rats in the sink
failed to suppress aggression in each other, and engaged in
31
The Sink that Didn’t Develop
A second series of experiments demonstrated the strategic
relationship between the sink and the conditioned need to eat
with other rats. In these experiments, Calhoun changed the type of food from pellet
to meal, so that food could be eaten quickly.
Water, on the other hand, was dispensed
from a slow fountain so that rats became
conditioned to drinking instead of eating
with other rats. This change kept the population more evenly distributed among the
”
pens; because rats normally drink immediately after awakening, they tended to stay
in their sleeping area. (For the previous ex- in
periment most of the rats had moved to the
pen where they ate.) There is some indication that in the second series, a sink would iv
eventually have developed, but for different
reasons. One male took over Pens III and IV, driving all
other rats out. A second male was in the process of establishing territorial rights to Pen II. When the experiment was
terminated, 80 per cent of the males were concentrated in
Pen I, the remainder, minus one, were in Pen II.
1
Summary of Calhoun’s Experiments
It is clear from Calhoun’s experiments that even the rat,
hardy as he is, cannot tolerate disorder and that, like man,
he needs some time to be alone. Females on the nest are particularly vulnerable, as are the young who need to be screened
from birth to weaning. Also, if pregnant rats are harassed
32
THE HIDDEN DIMENSION
too much, they have increased difficulty in bringing pregnancy to full term.
Probably there is nothing pathological in crowding per se
that produces the symptoms that we have seen. Crowding,
however, disrupts important social functions and so leads to
disorganization and ultimately to population collapse or largescale die-off.
The sex mores of the rats in the sink were disrupted, and
pansexuality and sadism were endemic. Rearing the young
became almost totally disorganized. Social behavior of the
males deteriorated, so that tail biting broke out. Social hierarchies were unstable, and territorial taboos were disregarded
unless backed by force. The extremely high mortality rates of
females unbalanced the sex ratio and thus exacerbated the
situation of surviving females, who were even more harassed
by males during the time they came in heat.
Unfortunately, there is no comparable data on wild rat
populations under extreme stress and in the process of collapse with which to compare Calhoun’s studies. It is possible,
however, that if he had run his studies longer the sink effect
would have built up to crises proportions. In fact, Calhoun’s
evidence certainly points to an imminent crisis. No matter
how they are viewed, the rat experiments were both dramatic
and complex. Yet it is doubtful that the many interacting
factors which combine to maintain a proper population balance could be identified from observations of the white Norway rats alone. Fortunately, however, observation of other
species has shed light on the processes by which animals
regulate their own density as a function of self-preservation.
THE BIOCHEMISTRY OF CROWDING
How can crowding produce the dramatic results—ranging
from aggression through various forms of abnormal behavior
to mass die-off—which we have seen in animals as different
as the deer, the stickleback, and the rat? Search for answers
to this question has produced insights with wide implications.
Two English researchers, A. S. Parkes and H. M. Bruce,
who were investigating the differing effects of visual and olfac-
CROWDING AND SOCIAL BEHAVIOR IN ANIMALS
33
tory stimulation on birds and mammals, reported in Science
that pregnancy in a mouse is suppressed by the presence of a
male mouse other than the original mate during the first four
days after conception. At first, the second stud males were
allowed to mate with the females during the period of vulnerability. Later it was demonstrated that the mere presence
of a second male in the cage would block pregnancy. Finally,
it was found that blocking would occur if a pregnant female
were introduced into an area from which a male had been
recently removed. Since the male was no longer present to be
seen by the vulnerable female, it was obvious that smell
rather than sight was the active agent. This assumption was
proved when it was demonstrated that destruction of the
olfactory lobe in the brain of the female mouse rendered her
invulnerable to the pregnancy-blocking capacity of the strange
male.
Autopsies of the females whose pregnancies were blocked
showed that the corpus luteum, which holds the fertilized
egg to the wall of the uterus, had failed to develop. Normal
formation of the corpus luteum is stimulated by a hormone,
prolactin, and pregnancy blockage can be prevented by injecting ACTH.
Exocrinology
Through their work Parkes and Bruce have radically modified prevailing theories of the relationship of the body’s
delicately balanced chemical control systems to the external
world. The ductless, or endocrine, glands have an influence
on virtually everything the body does and have long been
thought of as a closed system sealed in the body which is
only indirectly linked to the outside world. Parkes’ and
Brace’s experiments demonstrated that this is not always the
case. They coined the term “exocrinology” (as contrasted
with endocrinology) to express the expanded view of the
chemical regulators to include the products of odoriferous
glands scattered about the bodies of mammals. Odoriferous
substances are secreted from special glands anatomically situated in a variety of spots such as between the hoofs of deer,
below the eyes of antelope, on the soles of the feet of mice,
34
THE HIDDEN DIMENSION
CROWDING AND SOCIAL BEHAVIOR IN ANIMALS
on the back of the head of the Arabian camel, and in the
armpits of man. In addition, odoriferous substances are produced by the genitalia and appear in the urine and feces.
It is now recognized that the external secretions of one organism work directly on the body chemistry of other organisms and serve to help integrate the activities of populations
or groups in a variety of ways. Just as the internal secretions
integrate the individual, external secretions aid in integrating
the group. The fact that the two systems are interlinked
helps to explain in part the self-regulating nature of population controls and the abnormal behavior which follows excessive crowding. One syndrome revolves around bodily responses to stress.
Hans Selye, an Austrian working in Ottawa, whose name
has long been associated with studies of stress, demonstrated
that animals can die from shock if they are repeatedly
stressed. Any increased demand on the organism must be met
by the addition of energy. In mammals this source of energy
is blood sugar. If repeated demands exhaust the supply of
sugar available, the animal goes into shock.
directing controlled inflammation to combat them the cortex draws cashier’s checks on the liver. If the stress persists, a hormone called cortisone sends a worried message
to the pituitary. Preoccupied with the big picture, the
pituitary delegates a vice-presidential type, ACTH, or
adrenocorticotropic hormone, whose role is literally to
buck up the adrenal cortex. As students of Parkinson
would predict, the cortex, bucked, takes on more personnel, and expands its activities, including that of summoning more ACTH. The viciousness of the impending
spiral ought to be obvious, and ordinarily it is; but while
withdrawals continue, the amount of sugar in circulation
is deceptively constant (the work of another servomechanism) and there is no device, short of autopsy, for taking
inventory at the bank.
If the pituitary is conned by persisting stress into throwing more support to ACTH, the big deals begin to suffer
retrenchment. A cutback of ovarian hormone, for instance, may allow the cortex to treat a well-started foetus
as an inflammation to be healed over. Likewise, the glandular sources of virility and of maternity, though unequally prodigal of sugar, are equally likely to dry up.
Leaving hypertension aside (because it involves another
commodity, salt, which needn’t be gone into just now),
the fatal symptom can be hypoglycemia. A tiny extra
stress, such as a loud noise . . . corresponds to an unannounced visit by the bank examiner: The adrenal medulla is startled into sending a jolt of adrenalin to the
muscles, the blood is drained of sugar, and the brain is
suddenly starved. This, incidentally, is why shock looks
like hyperinsulinism. An overactive pancreas, like a panicky adrenal, resembles an untrustworthy teller with his
hand in the till.
The Sugar-Bank Model
Under the intriguing title “The Hare and the Haruspex,”
Yale biologist Edward S. Deevey recently explained the biochemistry of stress and shock in an effective metaphor:
It is possible to speak of vital needs as payable in sugar,
for which the liver acts as a bank. Routine withdrawals
are smoothly handled by hormones from the pancreas
and from the adrenal medulla, which act as paying tellers;
but the top-level decisions (such as whether to grow or
reproduce) are reserved for the bank’s officers, the adrenal cortex and pituitary glands. Stress, in Selye’s view,
amounts to an administrative flap among the hormones,
and shock results when the management overdraws the
bank.
If the banking model is gently dissected, it reveals its
first and most important servomechanism: a remarkably
bureaucratic hook-up between the adrenal cortex, acting
as cashier’s office, and the pituitary, as board of directors.
Injury and infection are common forms of stress, and in
35
The Adrenals and Stress
The reader will remember that the Sika deer showed greatly
enlarged adrenal glands just before and during the die-off.
This increase in size was presumably associated with increased demands for ACTH, which were due to increased
stress from crowding.
Following this lead, Christian in the late 1950s made a
study of seasonal changes in the adrenal glands of wood-
CROWDING AND SOCIAL BEHAVIOR IN ANIMALS
37
chucks. Among the 872 animals collected and autopsied over
a four-year period, the mean weight of the adrenals increased
as much as 60 per cent from March to the end of June, a
period when the male woodchucks were competing for
mates, were active for longer portions of the day, and more
of them were concentrated in a given area at the same time.
Adrenal weight declined in July, when the greatest number
of animals were active but aggressiveness was very low. The
weight rose again sharply in August, when there was exten-
Christian’s chart (1963) showing seasonal changes in the
weight of woodchuck adrenals in relation to the number
of animals. Note how population builds up from March
through June accompanied by decreased interaction distance, conflict, stress, and an increase in the weight of
the adrenals. Conflicts during the breeding season exacerbate stress. In July, as the young move out, the interaction distance increases and the endocrines return to
normal.
THE HIDDEN DIMENSION
CROWDING AND SOCIAL BEHAVIOR IN ANIMALS
sive movement among young woodchucks moving out to establish territories and there were frequent conflicts. Thus,
concluded Christian, “it seems that the lack of aggressiveness
was the most important consideration initiating the summer
decline in adrenal weight.”
their young. The lower-ranking male canaries thus had an
inviolate territory of their own and were therefore more successful in producing a brood than they otherwise would have
been.
The provision of individual territories for families and the
screening of animals from each other at critical times during
the mating season can counteract the ill effects of crowding
down to and including animals as low on the evolutionary
scale as the stickleback.
38
It is now widely held that the processes of selection which
control evolution favor the dominant individuals in any given
group. Not only are they under less stress but they also seem
to be able to stand more stress. Christian, in a study of the
“pathology of overpopulation” showed that the adrenals work
harder and become more enlarged in subordinate than in
dominant animals. Also, his own studies had demonstrated
that there is a relationship between aggressiveness and distance between animals. When aggressiveness was high among
male woodchucks during the breeding season, the mean interaction distance between animals increased. The mean
weight of the adrenals was correlated with the mean interaction distance, as well as with the number of interactions.
In other words, to paraphrase Christian, when aggressiveness increases, animals need more space. If no more space
is available, as occurs when populations are approaching a
maximum, a chain reaction is started. A blowup of aggressiveness and sexual activity and accompanying stresses overload the adrenals. The result is a population collapse due to
lowering of the fertility rate, increased susceptibility to disease,
and mass mortality from hypoglycemic shock. In the course
of this process, the dominant animals are favored and usually
survive.
The late Paul Errington, a gifted ethologist and professor
of zoology at Iowa State University, spent years observing
the effects of crowding on marsh muskrats. He came to the
conclusion that if collapse were too severe the recovery time
was immeasurably prolonged. The English investigator H.
Shoemaker showed that the effects of crowding could be very
considerably counteracted by providing the right kind of space
for certain critical situations. Canaries which he crowded into
a single large cage worked out a dominance hierarchy which
interfered with nesting of low-ranking birds until they were
provided with small cages where pairs could nest and rear
The
39
Uses of Stress
If we tend to deplore the results of crowding, we should
not forget that the stress which it produces has had positive
values. Such stress has been an efficient device in the service
of evolution, because it employs the forces of intraspecies
competition rather than the interspecies competition which is
more familiar to most of us as nature “red in tooth and claw.”
There is a very important difference between these two
evolutionary pressures. Competition between species sets the
stage on which the first types can develop. It involves whole
species, rather than different strains of the same animal. Competition within a species, on the other hand, refines the breed
and enhances its characteristic features. In other words, intraspecies competition serves to enhance the organism’s incipient form.
Present assumptions about the evolution of man illustrate
the effects of both pressures. Originally a ground-dwelling
animal, man’s ancestor was forced by interspecies competition and changes in the environment to desert the ground
and take to the trees. Arboreal life calls for keen vision and
decreases dependence on smell, which is crucial for terrestrial
organisms. Thus man’s sense of smell ceased to develop and
his powers of sight were greatly enhanced.
One consequence of the loss of olfaction as an important
medium of communication was an alteration in the relationship between humans. It may have endowed man with greater
capacity to withstand crowding. If humans had noses like
rats, they would be forever tied to the full array of emotional shifts occurring in persons around them. Other people’s
40
THE HIDDEN DIMENSION
anger would be something we could smell. The identity of
anyone visiting a home and the emotional connotations of
everything that took place in the home would be matters of
public record so long as the smell persisted. The psychotic
would begin to drive all of us mad, and the anxious would
make us even more anxious. To say the least, life would be
much more involved and intense. It would be less under conscious control, because the olfactory centers of the brain are
older and more primitive than the visual centers.
The shift from reliance on the nose to reliance on the eye
as a result of environmental pressures has completely redefined the human situation. Man’s ability to plan has been
made possible because the eye takes in a larger sweep; it
codes vastly more complex data and thus encourages thinking in the abstract. Smell, on the other hand, while deeply
emotional and sensually satisfying, pushes man in just the
opposite direction.
Man’s evolution has been marked by the development of
the “distance receptors”—sight and hearing. Thus he has been
able to develop the arts which employ these two senses to the
virtual exclusion of all the others. Poetry, painting, music,
sculpture, architecture, the dance depend primarily though
not exclusively on eyes and ears. So do the communications
systems which man has set up. In later chapters, we shall
see how the differing emphasis laid on sight, hearing, and
smell by cultures which man has developed has led to greatly
differing perceptions of space and the relations of individuals
in space.
IV
PERCEPTION OF SPACE: DISTANCE
RECEPTORS-EYES, EARS, AND NOSE
. . . we can never be aware of the world as such, but
only of . . . the impingement of physical forces on the
sensory receptors.
F. P. K l L P A T R I C K
Explorations
in
Transactional
Psychology
Study of the ingenious adaptations displayed in the anatomy, physiology, and behavior of animals leads to the
familiar conclusion that each has evolved to suit life in
its particular corner of the world . . . each animal also
inhabits a private subjective world that is not accessible
to direct observation. This world is made up of information communicated to the creature from the outside in
the form of messages picked up by its sense organs.
H.
W.
LlSSMAN
“Electric Location by Fishes,”
Scientific
American
These two statements pinpoint the importance of the receptors in constructing the many different perceptual worlds
that all organisms inhabit. The statements also emphasize
that the differences in these worlds cannot be ignored. In order
to understand man, one must know something of the nature
of his receptor systems and how the information received
from these receptors is modified by culture. Man’s sensory
apparatus falls into two categories, which can be roughly
classified as:
1. The distance receptors—those concerned with examination of distant objects—the eyes, the ears, and the nose.
2. The immediate receptors—those used to examine the
world close up—the world of touch, the sensations we receive
from the skin, membranes, and muscles.
THE HIDDEN DIMENSION
PERCEPTION OF SPACE: DISTANCE RECEPTORS
This classification can be broken down even further. The
skin, for example, is the chief organ of touch and is also
sensitive to heat gain and loss; both radiant and conducted
heat are detected by the skin. Hence, strictly speaking, the
skin is both an immediate and a distance receptor.
There is a general relationship between the evolutionary
age of the receptor system and the amount and quality of
information it conveys to the central nervous system. The
tactile, or touch, systems are as old as life itself; indeed, the
ability to respond to stimuli is one of the basic criteria of
life. Sight was the last and most specialized sense to be developed in man. Vision became more important and olfaction
less essential when man’s ancestors left the ground and took
to the trees, as I mentioned in the last chapter. Stereoscopic
vision is essential in arboreal life. Without it, jumping from
branch to branch becomes very precarious.
The unaided eye, on the other hand, sweeps up an extraordinary amount of information within a hundred-yard radius
and is still quite efficient for human interaction at a mile.
The impulses that activate the ear and the eye differ in
speed as well as in quality. At temperatures of 0°C. (32°F.)
at sea level, sound waves travel 1100 feet a second and can
be heard at frequencies of 50 to 15,000 cycles per second.
Light rays travel 186,000 miles a second and are visible at
frequencies of 10,000,000,000,000,000 cycles per second.
The type and complexity of the instruments used to extend
the eye and the ear indicate the amount of information handled by the two systems. Radio is much simpler to build and
was developed long before television. Even today, with our
refined techniques for extending man’s senses, there is a great
difference in the quality of the reproductions of sound and
vision. It is possible to produce a level of audio fidelity that
exceeds the ability of the ear to detect distortion, whereas the
visual image is little more than a moving reminder system that
has to be translated before it can be interpreted by the brain.
Not only is there a great difference in the amount and type
of information that the two receptor systems can process, but
also in the amount of space that can be probed effectively by
these two systems. A sound barrier at a distance of a quarter
of a mile is hardly detectable. This would not be true of a
high wall or screen that shuts out a view. Visual space, therefore, has an entirely different character than auditory space.
Visual information tends to be less ambiguous and more
focused than auditory information. A major exception is the
hearing of a blind person who learns to selectively attend the
higher audio frequencies which enable him to locate objects
in a room.
Bats, of course, live in a world of focused sound which
they produce like radar, enabling them to locate objects as
small as a mosquito. Dolphins, too, use very high-frequency
sound rather than sight to navigate and locate food. It should
be noted that sound travels four times as fast in water as it
does in air.
What is not known technically is the effect of incongruity
between visual and auditory space. Are sighted people more
likely to stumble over chairs in reverberating rooms, for ex-
42
VISUAL AND AUDITORY SPACE
The amount of information gathered by the eyes as contrasted with the ears has not been precisely calculated. Such
a calculation not only involves a translation process, but
scientists have been handicapped by lack of knowledge of
what to count. A general notion, however, of the relative
complexities of the two systems can be obtained by comparing
the size of the nerves connecting the eyes and the ears to the
centers of the brain. Since the optic nerve contains roughly
eighteen times as many neurons as the cochlear nerve, we
assume it transmits at least that much more information.
Actually, in normally alert subjects, it is probable that the
eyes may be as much as a thousand times as effective as the
ears in sweeping up information.
The area that the unaided ear can effectively cover in the
course of daily living is quite limited. Up to twenty feet the
ear is very efficient. At about one hundred feet, one-way
vocal communication is possible, at somewhat slower rate
than at conversational distances, while two-way conversation
is very considerably altered. Beyond this distance, the auditory
cues with which man works begin to break down rapidly.
43
44
THE HIDDEN DIMENSION
PERCEPTION OF SPACE: DISTANCE RECEPTORS
ample? Is it easier to listen to someone else if bis voice is
coming from one readily located spot instead of from several
loudspeakers as is characteristic of our P.A. systems? There
is some data, however, on auditory space as a factor in performance. A study by J. W. Black, a phonetician, demonstrated that the size and reverberation time of a room affects
reading rates. People read more slowly in larger rooms where
the reverberation time is slower than they do in smaller
rooms. One of my own inte…