RELAY

Olfactory Adaptation to Deafness and Blindness

Ruth Ann Smith

American Public University

Olfactory Adaptation to Deafness and Blindness

Introduction

Sensation and perception identify processes that differ primarily in their complexity. We have a greater number of senses than is widely believed. Psychophysics is the study of the relationship between physical events and our experience of those events. The absolute threshold is the smallest stimulus that arouses a sensation. The difference threshold is the smallest change in any stimulation that can be detected. (Bazhenov? 2009) The stimulus for vision is light? which has three physical characteristics: wavelength? intensity? and pureness. The psychological attributes are hue? brightness? and saturation. Complementary colors? as well as other colors? may be mixed in an additive or subtractive process. The receptor for vision is the eye? which contains rods for black-white vision and cones for color vision. Vision is poorest at the blind spot and best at the fovea. Dark adaptation and the Purkinje Shift both result from the shift from cone- to rod-vision. Color blindness affects mainly males? but it is a relatively slight vision problem compared to blindness. (Buck et.al. 2001)

Perception is based on certain factors of organization? including the figure-ground relationship. Another factor is the wholeness of figures (determined by symmetry? closure? and familiarity). A third is the grouping of elements (based on proximity? similarity? continuation? and common fate). Three other factors importantly involved in perception include attention? variations in stimulus input? and the constancies (shape? size? brightness? and color). There are two important jobs in visual perception. One is judging distance or depth? which is based on stimuli and cues within the organism. The other is detecting motion? which is based on the order in which sensing cells fire and/or movement relative to the environment or another object. In perceiving sound? our ability to locate a sound source is based on onset time? relative loudness? and phase differences of the sound waves reaching each ear. (Bazhenov et.al. 2010)

Sensation versus Perception

In the study of sensation and perception? one of the basic questions concerns how these two concepts relate to each other. Several years ago a nationally broadcast television show tried to clarify how humans respond to stimuli. The inside of the head was depicted as having a large television screen. On the screen were displayed all of the stimuli viewed by this human. Within the big head lived a much smaller person? who simply pulled levers to make the larger human respond. While this presentation explains nothing (who or what makes the little person respond?)? it does point out three basic elements involved when humans react to their environment. The first is the stimulus -- both its physical characteristics (what it is) and its psychological attributes (how we react to it). The second is the receptor? which receives the stimulus and sets the reaction in motion. Finally? there is the human organism itself -- both its prior experiences and its current physiological state. These three elements -- stimulus? receptor? and organism -- combine to determine the ways in ...