Chapter 9

Sensation and Perception

Charles Woods, Austin Peay State University and
John Krantz, Hanover University

Introduction

Studies of sensation and perception have historically been the starting points for the scientific study of the mind. An interest in the structure of sensory systems and the nature of human perception predates psychology. In fact, research in this area in the early and middle 1800ís was instrumental in creating the academic climate that gave rise to psychology as a distinct scientific field.

The year 1879 is often cited as the date of the founding of psychology, marked by the establishment of Wundtís experimental laboratory. The year 1860 is probably a better choice, however. This is the year that Fechner published his book Elements of Psychophysics (Boring, 1950). Fechner (below) described a set of methods for studying and quantifying the relationship between sensory stimuli and perceptual experiences. The realization that the relationships between stimulus events and mental events might be reducible to simple laws apparently occurred to Fechner while lying in bed on the morning of October 22nd, 1850 (Schultz & Schultz, 1996). This early work on the relationship between sensation and perception and the accuracy of the perceptual representations of sensory stimuli made up a substantial portion of the bedrock of early experimental psychology. Now, scientists celebrate Fechner Day (October 22^nd) each year with scientific meetings and other events in remembrance of this contribution to our field.

Gustav Fechner (1801-1887)
Image from the International Society for Psychophysics

The intervening 150 years of research on sensation and perception has led to technological advances in experimental apparatus, the discovery of new research methods for gathering observations, and the addition of advanced quantitative methods for describing and analyzing psychophysical data.

In the very early days, researchers in sensation and perception had fairly similar training and interests. Quite rapidly, however, work in the area diverged to include a broad set of research areas and scientific approaches. Today, the general area of sensation and perception is composed of researchers with vastly different training, and psychologists make up only a small percentage of these individuals. As sensory psychologists approach the millennium, they are re-examining their theoretical approaches to the traditional problems in the field, their selection of problems to investigate is heavily influenced by work in related fields (e.g. neuroscience), and they have become more applied.

Depth perception is a good example of the diversity of training and theoretical approach of todayís researchers in sensation and perception. Some sensory psychologists study how we use depth cues to help perform object recognition (de Vries, Kappers, & Koenderink, 1993) or to perform a visual search (OíToole & Walker, 1997). Others study how we recover 3-D shapes from motion cues (Lappin, Doner, & Kotas, 1980; Todd & Norman, 1991) or how we use depth cues to move through natural environments (Palmisano, 1996) or virtual ones (Cutting, 1997). In addition, neuroscientists study disparity sensitive cortical cells (Chino, Smith, Hatta & Cheng, 1997), optometrists study binocular function in the presence of strabismus or amblyopia (Yu & Levi, 1997), and biologists study depth perception in animals (Pettigrew & Konishi, 1976; Collett & Harkness; 1982).

Although scientific heterogeneity defines our field today, advances in the neurosciences heavily influence research in sensation and perception. This impact is understandable; we have made great strides in our understanding of the brain and we have developed exciting new research methods for investigating it. Only a handful of sensory psychologists would classify themselves as behavioral neuroscientists. However, most psychologists today are unlikely to investigate perceptual phenomena without at some point considering how their psychophysical data relate to the underlying sensory physiology or to brain organization.

Sensation and Perception Today

In the late 1990ís sensation and perception consists of many exciting research areas. These areas represent an expansive continuum from studies directed at the earliest, ìlow-levelî stages of sensory processing to those directed at later ìhigh-levelî perceptual mechanisms.

In this chapter we consider examples of what we feel are exciting areas of research in sensation and perception from both ends of this continuum, with an emphasis on the current state of the discipline. These examples, then, are primarily from the areas of vision and visual perception and represent both basic and applied science. We conclude with a brief discussion of possible future directions for the discipline, using as an example research in the area of virtual reality. Because it currently drives a great deal of the research and thinking in sensation and perception, we begin with current explorations in the area of visual neuroscience.