RATE OF INFORMATION PROCESSING IN VISUAL PERCEPTION - SOME RESULTS AND METHODOLOGICAL CONSIDERATIONS

Inadequacies involved in the methodologies for studying rate of information processing in visual perception were discussed in terms of current models and knowledge of visual perception. A different methodology was introduced based on a l0-channel tachistoscope which permitted the presentation of letter stimuli at varying rates. The task was visual search with Ss reguired to detect whether an A (target) had occurred in a sequence of letters presented on a trial. Each letter was presented for approximately 2 msec. with the rate between letters varing from 5 msec.-3 sec. In addition to rate, the number of letters presented in a trial (sequence length) and the location of the target in the sequence were studied. The only significant effect was the number of letters in a sequence. Detection sensitivity decreased with increasing sequence length. Control experiments indicated that this change in sensitivity was not attributable to an overloading of the encoding mechanism but rather was attributable to a change in the judgmental task. An increase in the number of noise letters disproportionately increased the number of false alarms relative to the hits. A simple probability model was able to describe the obtained results with fair accuracy. Presentation rate was immaterial. Detection was the same with only 5 msec. between letters in the sequence as with 3 sec. Failure to find a rate effect was interpreted in terms of filtering processes that operate in visual perception prior to the encoding process. (43 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.