viii Handbook of Psychology Preface

and for persons outside of psychology seeking information about psychological matters, the Handbook volumes
serve as a reference source for expanding their knowledge
and directing them to additional sources in the literature.
The preparation of this Handbook was made possible by
the diligence and scholarly sophistication of the 25 volume
editors and co-editors who constituted the Editorial Board.
As Editor-in-Chief, I want to thank each of them for the pleasure of their collaboration in this project. I compliment them
for having recruited an outstanding cast of contributors to
their volumes and then working closely with these authors to
achieve chapters that will stand each in their own right as

valuable contributions to the literature. I would like finally to
express my appreciation to the editorial staff of John Wiley
and Sons for the opportunity to share in the development of
this project and its pursuit to fruition, most particularly to
Jennifer Simon, Senior Editor, and her two assistants, Mary
Porterfield and Isabel Pratt. Without Jennifer’s vision of the
Handbook and her keen judgment and unflagging support in
producing it, the occasion to write this preface would not
have arrived.
IRVING B. WEINER
Tampa, Florida


Volume Preface

This volume is intended to provide thorough, accessible tutorials on the major topic areas in the field of experimental psychology. The volume should be useful not only as a reference
source for professionals, being part of this Handbook, but
also as an effective, stand-alone textbook for students. Consequently, the volume is aimed at professional psychologists,

entry-level graduate students, and advanced undergraduates
who have some relatively limited background in experimental psychology. Just as reading this volume does not depend
on reading the other volumes in the series, reading a specific
chapter in this volume is not contingent on reading any other
chapters. Each chapter provides an up-to-date, state-of-theart review of a specific subfield of experimental psychology,
providing coverage of what is known and what is currently
being done, along with some of the historical context.

experimental method. The use of experiments is widespread,
including, for example, research in biological, social, developmental, educational, clinical, and industrial psychology.
Nevertheless, the term experimental psychology is currently
limited to cover roughly the topics of perception, performance, learning, memory, and cognition. Although by
definition empirical in nature, research on experimental psychology is focused on tests of theories, so that theoretical and
experimental objectives and methods are necessarily intertwined. Indeed, research in experimental psychology has become progressively more interdisciplinary, with an emphasis
on not only psychological theories but also theories based on
other disciplines including those in the broader fields of
cognitive science and neuroscience. In addition, since its inception there has been a continued growth and relevance of
experimental psychology to everyday life outside of the laboratory. The potential applications of the results of psychology experiments are increasingly widespread and include, for
example, implications concerning teaching and training, law,
and medicine.

WHAT IS EXPERIMENTAL PSYCHOLOGY?
The experimental method is defined by the manipulation of
independent variables and the measurement of dependent
variables. Extraneous variables are either controlled or allowed to vary randomly. In particular, care is taken to remove
any variables that are confounded with the independent variables. Because of the control exerted, this method permits the
investigator to isolate causal relations. Any change in the dependent variables can be viewed as caused by the manipulation of the independent variables.
Experimental psychology has a rich heritage that started
when Wilhelm Wundt created the first psychology laboratory
in 1879 at the University of Leipzig. Because of the unique

ability to draw causal inferences with experiments, early psychology was essentially experimental psychology. Although
there are certainly those who think that the experiment is the
wrong methodology for many aspects of psychology, the primary methodological goal of most research in psychology
has been the exertion of as much control as possible, so that
the general idea of the experiment as the ideal research tool is
widely accepted in psychology.
Today the term experimental psychology does not, however, cover all of the areas in psychology that employ the

ORGANIZATION OF THE VOLUME
In covering the core topics of perception, performance,
learning, memory, and cognition, the volume is organized approximately from the least to the most complex processes.
Each of the first 23 chapters is focused on a different single or
pair of psychological processes. These chapters are divided
into eight sets with three chapters in each set but the last,
which includes only two. The sets cover the more general
topics of (a) modulatory processes, (b) sensory processes,
(c) perceptual processes, (d) human performance, (e) elementary learning and memory processes, (f) complex learning
and memory processes, (g) language and information processing, and (h) thinking.
Within the set of modulatory processes, we begin with
the fascinating topic of consciousness (and its inverse, unconsciousness), which has deep roots in philosophy as well
as in psychology. From there we delve into the topic of motivation and then the topic of mood. In addressing sensory

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Volume Preface

processes, we focus on three specific senses: vision, audition, and touch. More research has been conducted on vision

than on any other sense. Hence, the first chapter in this set
provides an overview of the theoretical and methodological
foundations of research on visual perception. Visual perception is covered from a different perspective in the following
set of chapters on perceptual processes. These include chapters focused on organization and identification processes in
the visual perception of objects, on depth perception and the
perception of events, and on speech production and perception. For the set of chapters on performance, we progress
through the topics roughly in the order in which they take
place, considering first attention, then action selection, and
finally motor control.
The set of chapters on elementary learning and memory
processes begins with two focused on work with animals,
the first on conditioning and learning and the second on animal memory and cognition, and concludes with one focused on work with humans, involving sensory and working
memory. For the set of chapters on complex learning and
memory processes, we include chapters on the specific
topics of semantic memory and priming, episodic and autobiographical memory, and procedural memory and skill acquisition, with each of these chapters containing coverage of
two different but related themes. The chapters on language
and information processing address first psycholinguistics,
with a focus on language comprehension and production,
then reading, with a focus on word identification and eye
movements, and finally the most complex of these processes, those involving text comprehension and discourse
processing. We end with other complex processes, those that
underlie thinking, again considering them in pairs, starting
with concepts and categorization and concluding with reasoning and problem solving.
Our final chapter provides a historical and modern
overview of applied experimental psychology, showing how
psychological experimentation addresses practical concerns.
The earlier chapters in the volume also provide some discussion of applications as well as a review of the historical development of their topic, but the emphasis on those chapters
is on recent empirical results and theory.

LIMITATIONS AND ACCOMPLISHMENTS

As should be clear from this outline, the volume is quite comprehensive in scope. Nevertheless, notable gaps could not be
avoided. For instance, in considering the sensory processes,
we could only focus on three of the senses, ignoring the

important senses of taste and smell. The length of the volume
did not allow us to include separate chapters on these senses,
and it proved to be unreasonable to expect one chapter to include a summary of more than one sense. There are also more
subtle omissions from our coverage because chapter authors
often, reasonably, chose to emphasize that aspect of their
topic that was of most interest to them or for which they
had the strongest background and expertise. To give just one
example, the chapter on perceptual organization and identification focuses on those processes as they occur in visual perception rather than including the similar processes in audition
and other senses. This is a single volume, but to provide a full,
complete, and detailed coverage of experimental psychology,
more than one volume would be necessary. In fact, John
Wiley & Sons has just published the third edition of the classic Stevens’ Handbook of Experimental Psychology, which is
now four volumes long. The original version appeared in
1951 in a single volume, and the increase in size since then reflects the large growth of research in this area. Readers of the
present volume who wish to delve more deeply into particular topics in experimental psychology are referred to the new
four-volume set of the Stevens’ Handbook.
The present volume makes up for any deficiency in quantity of coverage with its extraordinary quality of coverage.
When we were asked to edit this volume, we developed a
wish list of contributors including the leaders in each of the
specific chapter topics. We constructed a list including two or
three names of potential senior authors for each chapter. With
very few exceptions, the current volume is comprised of authors from that original list. Even though we thus had extremely high expectations about the chapters in the volume
from the beginning, in many cases the authors went way beyond our initial expectations because of the keen insights
they introduced in their chapters. Therefore, these chapters
serve not only as lucid summaries of the current state of the
field but also as roadmaps leading to the most fruitful

avenues of future investigation.

ACKNOWLEDGMENTS
We would like to express our deep appreciation to our team
of chapter authors for their exceptional contributions. In addition, we are indebted to a number of others who have
helped us in our efforts to put this volume together. First, we
are indebted to Irv Weiner, the editor-in-chief for the Handbook. Not only did he oversee the entire project, giving us invaluable guidance at each step as we progressed from the
early conception of the volume through the finished product,


Volume Preface

but he also read the draft of every chapter and offered many
valuable, specific comments and suggestions. Second, we
are grateful to our colleagues and collaborators, most notably Lyle Bourne and John Capaldi, for their helpful advice
at many stages of this project. Third, preparation of the book
and Chapter 11 benefited from the appointment of the second edition as a fellow of the Center for Behaviorial and
Social Sciences, School of Liberal Arts, Purdue University
during fall, 2000. The book preparation also benefited from
Army Research Institute Contract DASW01-99-K-0002 to

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the University of Colorado, which supported the first editor
during summer, 1999, 2000, and 2001. Finally but by no
means least, we wish to thank our spouses, Bruce Healy and
Janet Proctor, who have provided unfailing support, understanding, and encouragement as we required extra time to
devote to this project on top of our normal teaching, research, and writing schedule.
ALICE F. HEALY AND ROBERT W. PROCTOR