Memory-driven capture occurs for individual features of an object

Memory-driven capture during focused visual attention

Attention can be captured by the presence of distractors that match the current content of working memory in the visual field. This memory-driven capture is well established when observers adopt diffused attentional settings prior to the onset of memory-matching distractors. However, it remains unclear whether memory-driven capture can occur when observers are in a state of focused attention. The present study attempted to address this question by examining whether memory-matching distractors can disrupt performance on a focused attention task. Participants were asked to hold a sample word in working memory and then had to name a central color while ignoring an irrelevant distractor word in the visual display. In Experiments 1 and 2, the distractor word was always presented centrally within the focus of attention. In Experiment 3, the distractor word could be presented either at the center or at the periphery (i.e., outside the focus of attention). The results showed that the irrelevant distractor word within the focus of attention interfered with color-naming performance when it matched the sample word held in working memory. However, no interference effect was observed when the distractor word was presented outside the attentional focus. The present findings indicate that working memory-driven capture during a state of focused visual attention depends crucially on whether or not memory-matching distractors are positioned within the focus of attention.

Spatial Attention in Visual Working Memory Strengthens Feature-Location Binding

There is a debate about whether working memory (WM) representations are individual features or bound objects. While spatial attention is reported to play a significant role in feature binding, little is known about the role of spatial attention in WM. To address this gap, the current study required participants to maintain multiple items in their WM and employed a memory-driven attention capture paradigm. Spatial attention in WM was manipulated by presenting an exogenous cue at one of the locations that memory items had occupied. The effects of spatial attention on attention guidance in visual search (Experiment 1) and memory performance (Experiments 1 and 2) were explored. The results show that WM-driven attention guidance did not vary based on whether the search features came from the same object in WM; instead, it depended on the number of features, regardless of their source object. In memory tasks, the cued object outperformed the uncued object. Specifically, the test item was better rejected when the features were mis-bound in the cued location than in the uncued location. These findings suggest that memory-driven attention guidance is feature-based, and spatial attention in WM helps bind features into object structures based on location.

Common Neural Mechanisms Control Attention and Working Memory

Although previous studies point to qualitative similarities between working memory (WM) and attention, the degree to which these two constructs rely on shared neural mechanisms remains unknown. Focusing on one such potentially shared mechanism, we tested the hypothesis that selecting an item within WM utilizes similar neural mechanisms as selecting a visible item via a shift of attention. We used fMRI and machine learning to decode both the selection among items visually available and the selection among items stored in WM in human subjects (both sexes). Patterns of activity in visual, parietal, and to a lesser extent frontal cortex predicted the locations of the selected items. Critically, these patterns were strikingly interchangeable; classifiers trained on data during attentional selection predicted selection from WM, and classifiers trained on data during selection from memory predicted attentional selection. Using models of voxel receptive fields, we visualized topographic population activity that revealed gain enhancements at the locations of the externally and internally selected items. Our results suggest that selecting among perceived items and selecting among items in WM share a common mechanism. This common mechanism, analogous to a shift of spatial attention, controls the relative gains of neural populations that encode behaviorally relevant information.SIGNIFICANCE STATEMENT How we allocate our attention to external stimuli that we see and to internal representations of stimuli stored in memory might rely on a common mechanism. Supporting this hypothesis, we demonstrated that not only could patterns of human brain activity predict which items were selected during perception and memory, but that these patterns were interchangeable during external and internal selection. Additionally, this generalized selection mechanism operates by changes in the gains of the neural populations both encoding attended sensory representations and storing relevant memory representations.

Preparing for the unknown: How working memory provides a link between perception and anticipated action

What mechanisms underlie the transfer of a working memory representation into a higher-level code for guiding future actions? Electrophysiological correlates of attentional selection and motor preparation processes within working memory were investigated in two retrospective cuing tasks. In the first experiment, participants stored the orientation and location of a grating. Subsequent feature cues (selective vs. neutral) indicated which feature would be the target for later report. The oscillatory response in the mu and beta frequency range with an estimated source in the sensorimotor cortex contralateral to the responding hand was used as correlate of motor preparation. Mu/beta suppression was stronger following the selective feature cues compared to the neutral cue, demonstrating that purely feature-based selection is sufficient to form a prospective motor plan. In the second experiment, another retrospective cue was included to study whether knowledge of the task at hand is necessary to initiate motor preparation. Following the feature cue, participants were cued to either compare the stored feature(s) to a probe stimulus (recognition task) or to adjust the memory probe to match the target feature (continuous report task). An analogous suppression of mu oscillations was observed following a selective feature cue, even ahead of task specification. Further, a subsequent selective task cue again elicited a mu/beta suppression, which was stronger after a continuous report task cue. This indicates that working memory is able to flexibly store different types of information in higher-level mental codes to provide optimal prerequisites for all required action possibilities.

Training modulates memory-driven capture

Attention is captured by information matching the contents of working memory. Though many factors modulate the amount of capture, there is surprising resistance to cognitive control. Capture occurs even when participants are instructed either that an item would never be a target or to drop that item from memory. Does the persistence of capture under these conditions reflect a rigidity in capture, or can properly motivated participants learn to completely suppress distractors and/or completely drop items from memory? Surprisingly, no studies have looked at the influence of extensive training of involuntary capture from working memory items. Here, we addressed whether training leads to a reduction or even elimination of memory-driven capture. After memorizing a single object, participants were cued to remember or to forget this object. Subsequently, they were asked to execute a search task. To measure capture, we compared search performances in displays that did and did not contain a distractor matching the earlier memorized object. Participants completed multiple experimental sessions over four days. The results showed that attentional capture by to-be-remembered distractors was reduced, but not eliminated in subsequent sessions compared with the first session. Training did not impact capture by to-be-forgotten objects. The results suggest observable, but limited, cognitive control over memory-driven capture.