ABSTRACT

This chapter is concerned with feature perception, which is one type of qualitative information processing, and with stability and change in feature perception at different periods in human development. It focuses on the mechanisms of discrimination that are characteristic of sensory capacity and that give rise to feature perception. The chapter examines infrahuman parallels and biological bases of feature perception. It explores the perception in infancy, before much experience, and in maturity, after extensive experience. The chapter focuses on the distinction between qualitative and quantitative perceptual discriminations. The environment consists of several classes of energy, energy constantly in flux. Energy is the source of sensation, and change in energy provides information for perception. Discrimination of frequency and luminance is constant, whereas voice-onset time (VOT) and wavelength engender nonconstant discrimination even when measured under optimal spatiotemporal conditions. For VOT and wavelength, peaks and troughs in discriminability correspond with plateaus and boundaries of identification functions.