Previous research on the changes in perception which accompany aging has been dominated by two theories. One states that the visual stimulus lasts longer or is more persistent in the elderly. The other theory argues that the elderly are not able to filter or ignore irrelevant stimulus information. The theories were developed from a conception of visual information processing which assumes that with the onset of visual stimulus a literal, precategorical image or representation of the stimulus is placed immediately into a storage buffer, iconic memory, where the representation is held for a fraction of a second. Recent research has questioned this conception of iconic memory, however. On the basis of neurophysiological, psychophysical, and information processing experiments, it is argued that there is a continuous flow of information with the information needed to interpret various aspects of a stimulus developing at different rates following stimulus onset. A review of the aging literature in light of this new conception of iconic memory suggests the hypothesis that the elderly are deficient specifically in the processing of global form information which is carried by """"""""transient"""""""" neural channels. Groups of young and old subjects will be examined in a variety of paradigms to test the hypothesis that the elderly cannot maintain the integrity of large perceptual units during processing. Visual search, matching, and identification tasks will be employed. A unique aspect of the study is that several experiments will use stimuli that are computer generated to accentuate or eliminate spatial frequencies to which the elderly are less sensitive. Through choice of stimuli and tasks the experiments are structured in such a way that if the hypothesis is correct the older subjects will do better than the young subjects in some experiments but not in others. If the results are in the expected direction, support will be provided for the continuous flow conception of visual information processing as a unifying construct which accounts for a variety of observed effects attributed to iconic memory including changes associated with aging. Since most of our everyday functions depends on the processing of global form information, the demonstrated utility of the continuous flow model will lead to a better understanding of the problems the elderly have in such everyday tasks as face recognition and driving.
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| Gilmore, G C (1985) Letters are visual stimuli: a comment on the use of confusion matrices. Percept Psychophys 37:389-90 |
