Sequential whole report accesses different states in visual working memory.

Abstract

Working memory (WM) enables a rapid access to a limited number of items that are no longer physically present. WM studies usually involve the encoding and retention of multiple items, while probing a single item only. Hence, little is known about how well multiple items can be reported from WM. Here we asked participants to successively report each of up to 8 encoded Gabor patches from WM. Recall order was externally cued, and stimulus orientations had to be reproduced on a continuous dimension. Participants were able to sequentially report items from WM with an above-chance precision even at high set sizes. It is important that we observed that precision varied systematically with report order: It dropped steeply from the first to the second report but decreased only slightly thereafter. The observed trajectory of precision decrease across reports was better captured as a discontinuous rather than an exponential function, suggesting that items were reported from different states in visual WM. The following 3 experiments replicated these findings. In particular, they showed that the observed drop could not be explained by a retro-cueing benefit of the first report, a longer delay duration for later reports or a visual interference effect of the first report. Instead, executive interference of the first report reduced precision of subsequent reports. Together, the results show that a sequential whole-report procedure allows the assessment of qualitatively different states in visual WM. (PsycINFO Database Record

States in working memory store items with different memory quality

“…The current results replicated the findings from our previous study (Peters et al, 2018) by showing a discontinuous decrease of response precision, measured as the width of the response error distribution (inverted s.d.). That is, we observed a steep drop from the first to the second report and only a slight continuous decrease thereafter (Figure 1b, 1c).…”

“…Given the importance of interference for the distinction between high versus low memory quality storage, we sought to characterize in detail the interference processes that are responsible for the transfer of items from the first to the second state in working memory. In our previous study (Peters et al, 2018) we showed in two experiments that the steep drop in response precision from the first to the second report was due to the executive interference. Specifically, we have implemented executive interference by asking participants to orient a Gabor probe vertically (Experiment 3) or to change the color of a patch to blue (Experiment 4) during the retention period before first report.…”

“…For each trial, we computed response errors as the angular difference between the presented orientation and the response given by the participant. To compare the results with our previous study (Peters et al, 2018), we first computed response precision as the inverse of the SD of the response error distribution, corrected for the expectation value under uniform response errors (Bays, Catalao, & Husain, 2009). Response precision was calculated separately for each participant and condition.…”

“…Support for this dual-state architecture of working memory came mainly from behavioral studies that have reported different reaction times for items that were designed to be held in different states (McElree, 2006;Oberauer, 2002) and by findings of separable brain regions involved in accessing items in different states (Bledowski, Rahm, & Rowe, 2009;Nee & Jonides, 2014). Recently, we have provided further evidence that items in working memory are stored in two qualitatively different states (Peters et al, 2018). In contrast to a typical working memory task where multiple items are encoded while only a single item is probed, we applied a procedure where sequentially all encoded items had to be reported.…”

“…The experimental paradigm including the whole-report procedure was comparable to our previous study (Peters et al, 2018). At the beginning of each trial a memory array of two or four randomly oriented Gabor patches was presented for 400 ms (Figure 1a).…”