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Hiroyuki Tsuda, Jun Saiki; Gradual encoding and decay in visual working memory. Journal of Vision 2013;13(9):327. doi: https://doi.org/10.1167/13.9.327.
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© ARVO (1962-2015); The Authors (2016-present)
While capacity and representational format of visual working memory (VWM) have been extensively investigated, less is known about the processes involved in formation and decay of VWM representations. Zhang & Luck (2008) observed "all-or-none" transitions in VWM, proposing that participants store fixed-resolution representations of a subset of objects and retain no information about the others. Recently, we (Tsuda & Saiki, 2012) observed that memory precision varied depending on exposure duration of sample array, suggesting that precision of VWM is affected by how objects are perceived and consolidated, but precise temporal property remains unclear because of only a few duration conditions and of no proper control of duration with masks. In the current study we addressed whether transitions in VWM encoding and decay are all-or-none fashion or gradually assembled during encoding and gradually lost during retention interval, and how stimulus complexity affects these processes. In Experiment 1, different groups of subjects were presented with either static bars or point-light walkers with variable presentation durations, and asked to remember them across a 1000ms retention interval. Unlike previous study, sample display was followed by a mask. In the bar task they recalled the orientation of a bar and in the walker task the direction-of-heading of a walker was recalled. In the walker task, we observed that memory precision gradually improved as the presentation duration increased from 500ms to 5000ms, while in the bar task presentation duration had no effect on precision. In Experiment 2, participants were presented with 4 point-light walkers and recalled the direction-of-heading of walkers across variable retention intervals. We observed a decline in memory precision for longer retention intervals, which suggests a gradual decay in VWM. We conclude that when remembering perceptually complex stimuli, memory precision evolves gradually during encoding phase and decays gradually during retention interval.
Meeting abstract presented at VSS 2013
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