Separation or Integration of Sequential Arrays in VWM Depends On the interval Between Them

The visual information could be stored in either the active state or the passive state for a short time in visual working memory (VWM). Catering to the dynamic nature of visual world, we explored how the temporally dynamic input was stored in VWM by employing sequentially presented arrays rather than static arrays in which all items are presented simultaneously, and the contralateral delay activity (CDA), an electrophysiological measure was used to identify whether the memory items had been transferred into the passive state. In the current study, participants were instructed to encode two sequential arrays and retrieve them respectively, with two conditions of interval across the two arrays: 400ms and 800ms. These results provided strong evidence that two sequential arrays could be stored in VWM by forming two state-separated images if the interval between them was long enough, or by becoming an integration if the interval was relatively short. This conclusion was valid only when the participants encountered the task for the first time. Once participants have formed their mindset, they would apply the same memory mode to the subsequently extended or shortened interval condition. Therefore, the finding indicated that the extended interval could allow the storage transformation for the leading array, separated from the trailing array stored in the active state. Thus we proposed that the interval between two memory arrays influenced whether participants stored the two sequential arrays as parts of a single extended event or two independent episodes.