As discussed early in this chapter, recent discoveries in the behavioral neurosciences have greatly affected research in sensation and perception. An appreciation of the extent to which sensory systems process information in parallel required us to reconceptualize how sensory systems build our perceptual experiences. The advances in the behavioral neurosciences have led a substantial number of researchers to direct the focus of their research to explaining perception at this level of analysis. Today, research in sensation and perception often involves using psychophysical data to make inferences regarding the underlying neuroanatomy and neurophysiology. This theoretical approach to understanding sensation and perception, called neuroreductionism, has enjoyed great success. Many of the simpler perceptual phenomena can be explained by (or related to) the structure or function of underlying neural structures.

We have every reason to believe that this trend will continue and that other equally stunning discoveries are just around the corner. However, we need to recognize that in the future the neuroreductionist approach may result in diminished returns. Many of the perceptual phenomena that are amenable to simpler neuroreductionistic explanations have been described. Also, the extent to which this approach can provide similar and satisfactory explanations of higher-level perceptual phenomena remains to be demonstrated.

Additionally, as a theoretical approach to understanding perception, neuroreductionism has its share of detractors. William Uttal (1998), in his book Toward a new behaviorism: The case against perceptual reductionism, argues that researchers in sensation and perception should resist the very seductive enterprise of trying to link psychophysical data to specific underlying neural mechanisms. One of the theoretical problems associated with this approach, according to Uttal, is that neural events are not identical to mental events. Uttal calls this ìpsychoneural equivalence,î and he argues that it will always be difficult, if not impossible, to satisfactorily relate the two. He further adds that psychologists should not feel compelled to attempt it. Additionally, Uttal argues that ìÖif perceptual psychology is to survive, and not be inappropriately absorbed into the neural or computational sciences in the next millennium, it will have to return to its behaviorist, positivist rootsî (p. xii).

Although Uttalís (1998) argument is a compelling one, this large a shift in theoretical approach is unlikely. First, the neuroreductionist approach continues to provide us with valuable insights into sensory mechanisms. Second, the advent of superior brain imaging techniques, like the fMRI, have opened new avenues for researchers to visualize perceptionís neurological substrates in the awake, behaving human.

However, despite todayís neuroreductionist leanings, we still recognize that our individual perceptions are best described as gestalts, where the whole is far more than the sum of the anatomical or physiological parts. Also, many psychologists would agree that an understanding of these higher-order, emergent properties will do more to enhance our understanding of human sensation and perception than will neuroreductionist explanations involving the activity in small groups of neurons. Psychophysics, the set of methodological tools that sensory psychologists possess, is ideally suited to investigate perception at this level of analysis. Perhaps the unique promise of sensory psychology, relative to the other perceptual sciences, is that it does provide explanations of behavior at the molar rather than the molecular level. In a sense, this may be our ìscientific niche.î

We believe, then, that some of the most dramatic and important contributions that psychology will make in the near future will be in our understanding of higher-level perceptual mechanisms. We will see more studies of phenomenology, perception and action, and sensory integration. A good example of one of the intriguing research techniques and issues on the horizon for perceptual psychology is virtual reality (VR).