SENSORY PROCESSES AND MENTAL DEFICIENCY
Frank Kodman, Jr.
In the light of changing concepts in psychology, it would be rather foolish to dichotomize the sensoriperceptual continuum. Nevertheless, an attempt will be made to orient the information more toward the sensory event than toward the perceptual event. The reader should bear in mind that throughout this chapter, sensation and perception will not be viewed as dichotomous or discontinuous processes even though the contrary may at times appear to be the case. In addition to conceding that sensation and perception are causally related, one cannot ignore the important role of learning in these areas, nor can one ignore the interdependence of the sensory and motor systems. It is inevitable that some overlap will occur in discussions of sensation and perception in the present text. In most instances, the overlap will be treated from different points of view and should enrich the offering rather than detract from it.
Historically, sensory psychology was the primary interest of the new discipline, experimental psychology. Psychophysics developed from this interest and provided the basic methodology. At that time, there was a strong leaning toward physiology with its knowledge of the sensory organs and related nervous structures. Laboratory or experimental psychology received strong impetus from the work of E. H. Weber ( 1795 to 1878), a physiologist. There followed Weber's law and later the Weber-Fechner law which designated the relationship between the dimensions of the physical stimulus and its psychological correlatives. Fechner, ( 1801 to 1887), who was basically a physicist, felt that psychophysics applied to sensation and perception would make possible a definition of the dynamics involved in relating mind and matter to each other. With this beginning, experimental