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Joseph S Lappin, Adriane E Seiffert, Herbert H Bell; A Limiting Channel Capacity of Visual Perception: Spreading Attention Divides Perceptual Rates. Journal of Vision 2020;20(11):258. doi: https://doi.org/10.1167/jov.20.11.258.
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© ARVO (1962-2015); The Authors (2016-present)
How is the temporal process of perception affected by spreading attention to multiple objects? This study generalized the findings of another recent study, using different visual signals and a different detection task. Methods: During continuous watch periods, observers responded to sudden changes in either the color or direction of any one of a set of independently moving objects. The set size of moving objects was a primary variable. A simple detection task required responses to any display change, and a selective task required responses to a subset of the changes. Detection rates, in bits/s, were measured at successive times by response time (RT) hazard functions. Results: Increases in set size had a constant divisive effect on target detection rates. Moreover, variations in set size, visual target signals, and detection task exerted independent selective influence on detection rates at given times, reflecting continuous influence of parallel processes. Importantly, the divisive effect of increased set size was constant over time, invariant with rapidly changing detection rates controlled by the target signals and detection task. Conclusions: Contrary to conventional response time studies, the functional organization of these temporal processes was revealed by hazard functions but not by the RTs as such. The constant set size effects — invariant with response times, target signals, detection tasks, and with the developing influence of multiple component processes — indicate that conscious perception occurs at a measurable maximum rate, the result of a limiting channel capacity.
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