Deafness, Deprivation, and IQ

235 Pages·1994·3.917 MB·English

by  Jeffery P. Braden (auth.)

Deafness,
Deprivation,
andIQ
PERSPECTIVES ON INDIVIDUAL DIFFERENCES
CECIL R. REYNOLDS, Texas A&M University, College Station
ROBERT T. BROWN, University of Nonh Carolina, Wilmington
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DEAFNESS, DEPRIVATION, AND IQ
Jeffery P. Braden
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Allen Jack Edwards
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Edited by Jan Strelau and Alois Angleitner
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Deafness,
Deprivation,
andIQ
Jeffery P. Braden
University ojWisconsin
Madison, Wisconsin
SPRINGER SCIENCE+BUSINESS MEDIA, LLC
library of Congress Cataloging in Publication Data
Braden, Jeffery P.
Deafness, deprivation, and IQ I Jeffery P. Braden.
p. cm.-(perspectives on individual differences)
Includes bibliographical references and index.
ISBN 978-1-4419-3237-2 ISBN 978-1-4757-4917-5 (eBook)
DOI 10.1007/978-1-4757-4917-5
1. Deaf-Intelligence levels. 2. Deaf-Intelligence testing. 3. Deafness
Psychological aspects. 4. Deprivation (Psychology) I. Title. II. Title: Deafness,
deprivation, and intelligence quotient. m. Series.
BF432.D4B73 1994 94-2567
155.9'16--dc20 CIP
ISBN 978-1-4419-3237-2
© 1994 Springer Science+Business Media New York
OriginalIy published by Plenum Press, New York in 1994
AlI rights reserved
No part of tbis book may be reproduced, stored in a relIieval system, or transmitted in any form or by any
means, electronic, mechanicaI, photocopying, microfilming, reconiing, or otherwise, without written
permission from the Publisher
Foreword
Deafness is a "low incidence" disability and, therefore not studied or understood
in the same way as other disabilities. Historically, research in deafness has been
conducted by a small group of individuals who communicated mainly with each
other. That is not to say that we did not sometimes publish in the mainstream or
attempt to communicate outside our small circle. Nonetheless, most research
appeared in deafness-related publications where it was not likely to be seen or
valued by psychologists. Those researchers did not understand what they could
leam from the study of deaf people or how their knowledge of individual differ
ences and abilites applied to that population.
In Deafness, Deprivation, ami /Q, Jeffrey Braden pulls together two often
unrelated fields: studies of intelligence and deafness. The book includes the largest
single compilation of data describing deaf people's intelligence that exists. Here
is a careful, well-documented, and very thorough analysis of virtually ali the
research available. Those who have studied human intelligence have long noted
that deafness provides a "natural experiment." This book makes evident two
contrary results: on the one hand, some research points to the impact deafness has
on intelligence; on the other hand, the research supports the fact that deafness has
very little, if any, impact on nonverbal measures of intelligence.
Braden's meta-analysis of these studies leads to some very interesting find
ings, the most remarkable of which are the similarities between deaf and hearing
people. The book shows that the impact of deafness on intelligence is simply to
depress verbal IOs and not affect nonverbal IOs. At the same time, deaf children
with deaf parents have performance IOs that are above the mean for hearing
people.
The natural experiment of deafness has been available for centuries. What is
new here is the emphasis that deafness does not represent an experiment solely
v
vi Forewonl
with respect to language deprivation. Previous characterizations of deafness, were
often simplistic, described deafness as a condition in which the primary (and often
the only) independent variable was language. What is new and important here is
the very careful presentation of dysfunction and abnormal family dynamics, which
would very likely have a significant impact on intellectual development.
Much of the discussion in this book about group differences in intelligence
is controversial. No single area within psychology has generated more debate than
group differences in intelligence. Similarly, in the study of deafness, the field
continues to be divided as to whether or not differences exist between deaf and
hearing people that are due solely to deafness. While the literature reflects ex
tensive research and theorizing about intelligence, much of the research on deaf
ness is atheoretical and descriptive. Braden brings an important scientific rigor to
the analysis of deafness research. His book has the potential to serve both deafness
and psychology research in the areas where they overlap.
As a psychologist who has spent my entire career working in the field of
deafness, I have been terribly disappointed that the value of studying our com
munity has been overlooked by mainstream psychology. Some of this disregard
has been difficuIt for me to understand. How, for example, can anyone continue
to discount differences between verbal and nonverbal intelligence measures after
seeing the differences that exist among deaf people? This book clearly shows that
by studying deaf people we can leam a great deal about nature and nurture and
about the genetic and environmental influences on intelligence.
Reading this book will reveal much of the debate that still exists in these
fields. More importantIy, it will reveal some light. Braden has done a remarkable
job of bringing these two disparate fields together.
Little is more valued within the academy than the achievements of one's
student. AlI of us believe, on some level, that within each of the students lies the
potential to rise high above the norm. Each of us is quick to take some credit when
one of our students stands out. It is a special privilege for me to write an in
troduction to a book written by just such a former student.
I first carne to know Jeff Braden when he attended Gallaudet University for
a year as an undergraduate. The drive and potential in him were clear. As a student
in my course on Psychological Design and Statistics, Jeff proceeded through the
materials so rapidly that he and I soon agreed he would become more of a teaching
assistant than a student. He quickly leamed that to teach something one must really
understand it. Deafness, Deprivation, and IQ is the work of a researcher, a scholar,
and a teacher.
1. KING JORDAN
President
Gallaudet University
Washington, D.C.
Preface
I can think of no psychological issue that has generated more controversy than the
effect of nature and nurture on the development of human intelligence. The
relative contributions of genetics (nature) and environment (nurture) to the dif
ferences in IQ found among ethnic, racial, and gender groups is hotly debated.
This debate has been carried forward with more passion than precision; with more
conviction than caution. Even careful scholarly research (e.g., Flynn, 1986; cf.
Jensen, 1969, 1980) has been acclaimed or attacked for the popularity or un
popularity of its conclusions rather than its scientific merit. The fuel that fires this
controversy is a volatile mix of strongly held convictions about the way things
ought to be and a host of contrary facts. In an egalitarian society, we want alI
groups to be equal not only with respect to rights and opportunities, but also with
respect to outcomes. It offends OUT sensibilities that some groups, particularly
those which have been historical victims of discrimination, do not perform as well
as more privileged groups on tests of intelligence and aptitude. It is especialIy
painful to consider that these differences might be more strongly influenced by
differences in genetics than by differences in environment. For these and other
reasons, the research on the causes of between-group differences in intelligence is
emotional, often unpleasant, and voluminous.
In contrast to the fame (infamy?) of nature-nurture research, the psycholog
ical study of deafness remains obscure. The few scientists who have attempted to
link the study of deafness with larger psychological issues (e.g., Rudolph Pintner,
Hans Furth, McKay Vemon, Oliver Sacks, Ursula BelIugi, and Edward Klima)
stand in rare company. As a consequence, most psychologists know little of nor
understand the psychological significance of research on deaf people.
This book is an attempt to bridge the prominent subject of group differences
with the obscure subject of deafness. This bridge is an important link between two
vii
viii Preface
fields of investigation that were previously unrelated, yet have so much in com
mon. What constitutes environmental deprivation, and the impact of environ
mental deprivation on intelligence, has been vigorously studied by scholars in
terested in the nature-nurture debate, and by scholars interested in deafness. Sadly,
these investigations have coexisted in apparent isolation from each other. My·
purpose in writing this book is to build a bridge between these two lines of inquiry,
so that each can learn from the other.
My effort to build such a bridge reftects my own journey into the fields of
deafness and psychology. I spent my junior undergraduate year as an "exchange
student" at Gallaudet University (then Gallaudet College). During that time, I met
a young assistant professor of psychology, Dr. 1. King Jordan, who inspired me to
change my major and pursue a career in psychology. (Dr. Jordan is now president
of Gallaudet University, and the first deaf president in Gallaudet's distinguished
history.) Later, I returned to Gallaudet for graduate training in school psychology.
After graduating from Gallaudet, I began working as a school psychologist at the
California School for the Deaf in Fremont, California.
My interest in deafness was fully developed when I met Dr. Arthur Jensen
at the University of California. I entered Berkeley in pursuit of my doctorate in
school psychology, and began taking courses with Professor Jensen in part be
cause I wanted so desperately to show him the error of his ways. I had been led
to believe that the issue of between-group differences in intelligence had been
irrevocably decided in favor of egalitarians, and only dogmatists (or worse) stiH
clung to the antiquated belief ihat some racial and ethnic groups had lower IQ
distributions than other groups.
Although my efforts to dispute Dr. Jensen had Httle impact on his views, they
had a profound effect on mine. In my struggle to understand the nature and causes
of between-group differences in intelligence, I reached for research on deafness as
a comparison group. As I argue in this book, deaf people suffer profound depriva
tion as a result of their hearing loss. I was sure that the study of intelligence in deaf
people would iHustrate the ways in which environmental deprivation caused
impoverished intelligence and consequent low IQs. Certain as I was to find this
conclusion, I reasoned that I could then proceed to show how environment, not
genetics, caused lower IQs among disadvantaged, deprived groups. Sadly, my
efforts culminated in a trauma well known to scientific history, namely, my
perfectly good theory was ruined by my data. As I show in this book, the issue is
far more complicated, and leads to a less comfortable outcome than the one which
I anticipated when I began my work.
My hope is that this book wiH succeed in opening dialogue between pre
viously isolated interests. I do not pretend that the book represents the only, best,
or most definitive conclusions to be drawn by linking research on deafness with
nature-nurture research in intelligence. I have no doubts that some wiH object to
my conclusions; I, too, did not part lightly with my dearly held beliefs. More
Preface ix
important, 1 hope others will critique my methods and elucidate ways in which
these disparate fields of inquiry should, and should not, be linked. If this book
prompts those interested in nature-nurture issues to consider a broader range of
data, or encourages those interested in deafness to frame their work in terms of
larger issues in psychology, it will be a success.
There are many who have contributed to the development of this book. The
efforts of Cecil Reynolds and Eliot Wemer, who stayed with me through sub
stantial revisions and significant delays, are appreciated. Without my parents, who
taught me that honesty is more important than conformity, 1 would never have
found the persistence needed to finish the book. The inftuence of my teachers,
especially Professors Jordan and Jensen, is evident throughout. Finally, 1 want to
acknowledge Jill Serota Braden, my editor, friend, and wife, and my children,
Rachel and Daniel, without whose love and support my work would not have been
possible.
Contents
Foreword by l. King Jordan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Chapter 1 Deafness as a Natural Experiment . . . . . . . . . . . . . . . . . . . 1
Philosophica1 Perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
The Relationship between Thought and Language . . . . . . . . . . . . . . . . . 1
Efforts to Serve Deaf People .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Scientific Perspective. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Outcomes of the Natural Experiment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Implications for Understanding Language and Intelligence . . . . . . . . . . 8
Implications for IQ Differences between Groups . . . . . . . . . . . . . . . . . . 9
Problems with Natural Experiment Conclusions . . . . . . . . . . . . . . . . . . . . . 11
Simplistic Assumptions Regarding Deafness. . . . . . . . . . . . . . . . . . . . . . 11
Problems of Analysis and Synthesis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Organization and Overview of the Remaining Chapters.. . . ... . .... . .. 12
Chapter 2 Deafness as a Natural Experiment-Revisited .. . . . . . . . 15
Auditory Deprivation and Hearing Loss .. . . . . . . . . . . . . . . . . . . . . . . . . . 15
Definition of Hearing Loss ............... ,. . . . . . . . . . . . . . . . . . . . 16
Definition of Deafness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Summary of Auditory Deprivation and Hearing Loss. . . . . . . . . . . . . . . 25
Language Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Degree of Language Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Language Modality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Language versus Modality . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
xi