This book describes the methods, theories, and applications of classical and
modern psychophysics. It was written for advanced undergraduate students
with some background in statistics; graduate students may also find it useful
for obtaining an overview of the field. I hope Psychophysics: The Fundamentals
will be useful for courses in perception, general experimental psychology, and
quantitative methods.

Twelve years have passed since the publication of the second edition of this
book. In this third edition, I have included many of the methodological and
theoretical contributions made in the field during this time period. I have also
expanded on some of the topics found in the first and second editions. The
major additions found in this book are descriptions of adaptive procedures for
measuring thresholds, context effects in scaling, theory of quantal fluctuations,
multidimensional scaling, nonmetric scaling of sensory differences, and the
relationship between the size of the DL and the slope of the sensation magni-
tude function. New methods have also been included for measuring the ob-
server's sensitivity and criterion and the discussion of category scaling has been
expanded to include the range frequency model and verbally labeled categories.
Methods used to control the observer's nonlinear use of numbers in magnitude
estimation such as line-length scaling, magnitude matching, master scaling and
category-ratio scaling are described. Finally, a glossary of terms is added.

I wish to acknowledge the special efforts of Sandy Bolanowski, Gene Galanter,
Neil Macmillan, Larry Marks, Joe Sturr, and John Swets in providing me with
their constructive criticism and helpful suggestions after reading various ver-
sions and sections of the manuscript. I would also like to thank my students
for their support and helpful suggestions, Nancy Wichmann for her typing and
help in putting the final manuscript together, Chris Ingersoll for her excellent
artwork, and Marcy Pruiksma, Book Production Editor, for coordinating dif-
ferent facets of this project.

-- George A. Gescheider

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