Visual Pattern Analyzers

This is a book of psychophysics, the branch of psychology which deals with the relation between physical stimuli and sensory response, usually as determined by a person's report of what he has detected. Such reports sometimes provide evidence for physiological processors. Evidence for the existence of three color analyzers, which we now know to be cells in the eye with three kinds of pigments, was found in the nineteenth century in psychophysical exeriments.The experiments analyzed in this book present people with sinusoidal gratings (which look like striped patterns with alternating, blurry, light and dark stripes) at near threshold values (close to the point where the stimulus is just barely detectable). This choice of subject matter was dictated by the fact that such experiments produce consistent results from which conclusions can be drawn about the nature of the analyzers at an early stage of visual processing.Sinusoidal grating can differ in 17 dimensions, such as: spatial frequency or the width of the stripes; orientation or the angle of the strips; temporal dimensions which vary when the grating changes over tieme. For each dimension the author ends by summarizing whether there are one or multiple analyzers; how broad the bands of response of multiple analyzers are; and whether one can tell which analyzer is responding.Physiological experiments on response of individual neurons in cats and monkeys to visual stimuli are also considered. The author concludes that the analyzers discovered by the psychophysical experiments on people reside in the primary visual area of the cortex.The bulk of the book is about the logic and the mathematics necessary to draw such conclusions and should be of interest to people who want the study senses other than vision. There is a a chapter introducing the necessary mathematical techniques (Fourier analysis). Each of four psychophysical techniques is considered separately: adapatation, summation, uncertainty, and identification.There are extensive references aranged by topic. However, although this paperback edition was published in 2001, the book has not been revised since its hardcover publication in 1989, so the references are not very recent.The intended audience for this book is "a graduate student in vision or perception or an established researcher in another area of vision.. [or].. people working in the psychophysics of audiion, taste or smell" (p. viii). For these, and perhaps some others, it is an excellent book. Despite the rigors of the math and analysis, it is written very clearly.