Guidance of attention by working memory is a matter of representational fidelity

Abstract

Previous research shows that a single visual working memory item can guide visual attention towards objects that match the feature held in mind, but the results are mixed as to whether this attentional guidance occurs for multiple concurrently active working memory items or not. Evidence in favor of a single-item guidance account has been taken as evidence for the structure of working memory comprising multiple distinct states where one item is prioritized over all others by being placed within a special focus of attention. The present study was designed to test attentional guidance effects for single and multiple working memory items, and to test the hypothesis that there are special distinct states in working memory. To do so, we asked participants to remember one or two colors, then perform a visual search task, and then report the items held in mind. We demonstrate that a single working memory item robustly biases attention towards items that match the color maintained in working memory during visual search (Exp. 1). Although we found reliable guidance when participants remembered two items, we show that these effects can largely be explained by a single item guiding attention on a proportion of trials (Exp. 2). Next, by precisely measuring memory for individual items we show that items naturally vary in their representational fidelity, and that only the item with the strongest representation guides attention (Exp. 3). Importantly, we demonstrate that no special focus of attention is necessary to explain these single-item guidance effects but that natural variation in the fidelity between items — which arises through independent noise — can account for the effects (Exp. 4). These findings challenge current models of working memory guidance and propose a simpler account for how working memory and attention interact: through natural variation in the representational fidelity of memories, one item tends to be the dominant item guiding attention on any individual trial.

The capacity of multiple-target search

“…For example, a model in which the processing capacity is conceptualized as a resource that is flexibly distributed over all target representations (cf. Bays & Husain, 2008;Ma et al, 2014;Williams et al, 2019), but in an unequal way, such that one representation receives the bulk of the resource at the expense of the other, would make predictions very similar to those of the serial models. Another possibility would be a system that relies on both parallel and serial subsystems.…”

The object as the unit of interaction between visual working memory and visual attention

“…However, this hypothesis can hardly explain our findings because previous studies showed that the memory strength of two different colors (probed by VWM performance) was not beneficial when presenting them as an integrated object (e.g., Fougnie et al, 2010;Olson & Jiang, 2002;Wheeler & Treisman, 2002;Xu, 2002). Furthermore, previous studies tried to address the debate by focusing mainly on assessing whether and when multiple items can simultaneously interact with attention (e.g., Bahle et al, 2019;Olivers, et al, 2011;van Moorselaar, et al, 2014;Williams et al, 2019). However, our study went beyond by exploring how to increase the interaction efficiency for multiple representations and demonstrated that chunking multiple colors into a single integrated object was an effective way to enhance their ability to guide attention.…”

“…When multiple colors are represented as separate objects in VWM, these objects may compete with each other to interact with attention, resulting in a decreased ability to guide attention. This might explain why in previous studies the attentional capture effect with multiple items was not as reliable as a single item (e.g., Beck & Vickery, 2019;Hollingworth & Beck, 2016;van Moorselaar et al, 2014;Williams et al, 2019). In addition, as the object is the interactive unit between VWM and attention, the efficiency of the interaction should be mainly determined by the number of objects, instead of the number of features (even from the same dimension) or Boolean maps involved in each object.…”

“…However, attentional guidance by multiple items has still been observed even after reducing the chunk probability of two cued colors in the final experiment of Bahle et al (2019), indicating that chunking strategy is probably not the only factor influencing attentional guidance. In fact, Williams et al (2019) claimed that the representational strength of memory items determines their ability to guide attention. However, this hypothesis can hardly explain our findings because previous studies showed that the memory strength of two different colors (probed by VWM performance) was not beneficial when presenting them as an integrated object (e.g., Fougnie et al, 2010;Olson & Jiang, 2002;Wheeler & Treisman, 2002;Xu, 2002).…”

“…For instance, when participants were asked to hold a single feature (e.g., color) in VWM, and then perform a visual search task, their attention was captured by any stimuli with that feature, even if it was a distractor rather than a search target; this phenomenon is known as the memory-driven attentional capture effect (Olivers et al, 2006;Soto et al, 2005). However, the results have been mixed when multiple items are held in VWM, with some studies showing that attentional guidance can occur with multiple items (e.g., Bahle et al, 2019;Grubert & Eimer, 2015;Hollingworth & Beck, 2016;Zhou et al, 2020), while others have not reported such an effect even using similar paradigms (e.g., Beck & Vickery, 2019;Hollingworth & Beck, 2016;van Moorselaar et al, 2014;Williams et al, 2019).…”