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Zhi Li, Keyun Xin; Visible persistence speeds up visual search. Journal of Vision 2020;20(11):483. doi: https://doi.org/10.1167/jov.20.11.483.
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© ARVO (1962-2015); The Authors (2016-present)
Iconic memory has been considered as the very first storing stage in human visual system. While it is still not clear what role iconic memory plays in vision, two distinctive components of iconic memory, i.e., visible persistence (VP) and informational persistence (IP), have been identified. Visible persistence is relatively brief (150 ms) and is thought of as a pre-categorical visual representation of the physical stimuli. It appears that visible persistence would not have a real function in vision. However, in the present study, we had an astonishing discovery that visual search is more efficient when VP of the search display is available than when it is not. We found a clear turning point in the search time x set size function using a TSED (threshold stimulus exposure duration) paradigm (Li et al., 2019). The turning point showed up at set size 4 for letter stimuli but at set size 7 for color stimuli, suggesting that it is not due to the working memory capacity of remembered locations (which should predict a turning point at fixed set size irrespective of the content of search). For both letter and color, search time of the turning point was closely matched to the duration of visible persistence of the search array. Moreover, this turning point disappeared when the starting time of search was delayed so that VP of the search display was no longer available during search. The enhancement in search efficiency is not due to a faster individuation, because a turning point was found at set size 4 for both the letter and color stimuli in a subitizing paradigm. These findings suggest that visible persistence might support faster visual comparison that occurs in most visual tasks and thus reduces the burden of working memory.
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