Recall cues interfere with retrieval from visuospatial working memory

Abstract

Visuospatial working memory allows us to hold multiple visual objects over short delays. It is typically tested by presenting an array of objects, then after a delay showing a 'probe' indicating which memory item to recall or reproduce by adjusting a target feature. However, recent studies demonstrate that information at the time of probe can disrupt recall. Here, in three experiments we test whether traditional memory probes, which contain features that compete with the feature to be recalled, may themselves interfere with performance. We asked participants to report the direction of one of the several coloured arrows in memory, based on its colour. First, we demonstrate that recall is better when the probe is initially just a coloured dot, rather than a coloured arrow which has to be adjusted to match orientation memory, consistent with interference from features of the probe itself. Second, this interference is present even when a mask follows the memory array, suggesting that the interference does not work by degrading immediate or iconic memory. Finally, when items are shown sequentially, the first and last items are invulnerable to probe interference. Our findings support recent theories of associative recall, in which probes reactivate features in WM, retrieving information by pattern completion.

Keywords: recall cues; retrieval; visuospatial working memory.

Figure 1

Schematic of pattern completion with a colour‐only versus a compound probe. (A) When participants are presented with a memory array and are asked to keep the items’ colours and orientations in mind, they encode both dimensions for each item and bind them together into objects. After a memory delay, participants are presented with a either colour‐only probe that only holds information on one dimension or compound probe that holds information on two dimensions. (B) In case of the colour‐only probe, this colour cue can reactivate the corresponding orientation information, by pattern completion. This could allow participants to report the appropriate item's orientation (Manohar et al., 2017). The bold line represents activation though pattern completion. (C) However, when participants are presented with a compound probe, such as used in many previous studies, the probe holds not only the colour cue, but also irrelevant information on an orientation that is different from the encoded item. This additional information could interfere with reactivating items from memory (dashed bold line). In this example, the probe's orientation might interfere with irrelevant information previously stored such as another orientation (flash). [Colour figure can be viewed at wileyonlinelibrary.com]

Figure 2

Design and mean absolute error for Experiment 1. (A) Participants had to remember the orientations of a set of coloured arrows. Three or five items were presented in the memory array, and after a delay, one of the arrows was probed by their colour. In the ‘arrow probe’ condition, the probe was a compound object, that is, a coloured arrow that had to be adjusted to the remembered orientation, by moving the mouse. In the ‘dot probe’ condition, the probe was a coloured dot (no irrelevant orientation information, colour only), which turned into an arrow as soon as the mouse was moved. (B) The arrow probe significantly impaired recall–precision (p = .029). As expected, memory was worse when more items had to be stored (p < .001), but there was a significant interaction between the probe type and number of items in the array. The error bars were calculated by subtracting each subject's grand mean away from their individual per‐condition values and showing ± the standard error (Loftus & Masson, 1994). [Colour figure can be viewed at wileyonlinelibrary.com]

Figure 3

Design and mean absolute error for Experiment 2. (A) Three arrows were presented in the memory array and either followed by a mask of 1,000 randomly orientated and coloured arrows or a black delay screen. The probe could be a coloured arrow or dot, just as in Experiment 1. (B) Replicating the interference effect observed in Experiment 1, we found that recall was worse with a compound probe (p = .003). Masking also significantly impaired recall–precision (p = .002). But crucially, there was no interaction between the probe type and masking. The error bars were calculated by subtracting each subject's grand mean away from their individual per‐condition values and showing ± the standard error (Loftus & Masson, 1994). [Colour figure can be viewed at wileyonlinelibrary.com]

Figure 4

Design and mean absolute error for Experiment 3. (A) Four coloured arrows were sequentially presented in the memory array. The probe could be a coloured arrow or dot, as previously described. (B) There was a significant interaction between the probe type and the serial position of the target item in the sequence (F(3,39) = 5.19, p = .004). Pairwise tests indicated that recall error was greater for the arrow probe only for the second (p = .016) and third (p = .004) serial positions, but not for the first (p = .26) or last item (p = .31) in the sequence. The error bars were calculated by subtracting each subject's grand mean away from their individual per‐condition values and showing ± the standard error (Loftus & Masson, 1994). [Colour figure can be viewed at wileyonlinelibrary.com]

Figure 5

Plots of Bayesian hierarchical model fits for Experiments 1–3 (left to right). Plots for target response in the first line, for non‐target responses in the second line, for guessing responses in the third line, and for precision in the bottom line. Error bars represent highest density interval from a sample of representative values, estimated as shortest credible interval (Oberauer et al., 2017). [Colour figure can be viewed at wileyonlinelibrary.com]