What working memory actually does to a distractor
When you hold something in working memory during a search, it can change how much a matching distractor interferes. In a dual-task study, people memorized a written color word while searching for a gap-location target. When the word's meaning matched the color of one of the distractors, response times were reliably faster, but only in the control group under visual-only conditions [4]. That pattern suggests memory content can make a matching distractor easier to handle, not harder, at least for some people.
Adding sound during memory encoding changed the picture. Both the substance-use-disorder group and the control group showed comparable facilitation when congruent auditory information was present, though the effect appeared later in the substance-use-disorder group. The audiovisual benefit was also larger and longer-lasting than the visual-only benefit [4]. The study's authors frame this as working memory, selective attention, and audiovisual enhancement interacting to optimize perceptual decisions, but the design cannot say which of those is doing the causal work.
Suppression has a spatial shape, even without memory
Distractor suppression is not all-or-nothing at the distractor's location. In a study using behavioral data and EEG from adult humans, reaction times and neural indices of target selection improved steadily as the distance between target and distractor increased [2]. In other words, the farther the target sat from the salient distractor, the less the distractor hurt.
The neural side matched the behavior. The distractor positivity, an EEG signal that tracks suppression, declined monotonically with distance, and multivariate analyses found spatially selective theta-band activity with suppressed activity at channels centered on distractor positions [2]. The authors conclude that goal-driven selection benefits from a spatial gradient of suppression around salient distractors. This is evidence about spatial guidance, not about memory-guided attention, so it describes the baseline geometry that memory effects would have to work within.
Theta rhythms as a possible control channel
A causal study asked whether mid-frontal theta activity actually drives memory-guided search rather than merely accompanying it. Using a single-blind, sham-controlled between-subject design, participants performed a visual search task with distractors while theta stimulation was applied [3]. The abstract reports that theta activity modulates memory-guided visual search and distractor suppression, which is consistent with theta serving as a control signal rather than a byproduct.
The scope matters here: the finding is about mid-frontal theta stimulation in a memory-guided search task, and the abstract does not specify how large the effects were or which memory system was engaged. It supports a causal role for theta in this setting without establishing that theta is the mechanism for every kind of memory-guided suppression.
Why different memory systems may not act at the same moment
Putting the strands together, memory-guided suppression and spatially guided suppression seem to operate on different clocks. Spatial suppression around a distractor is present as a graded field that shapes target selection moment by moment [2], while working-memory effects on a matching distractor show up as a response-time advantage that can be shifted later by adding auditory information during encoding [4]. Theta activity is a plausible route by which memory-related control reaches the search process [3].
What remains genuinely open is how these systems combine. The dual-task study shows that working-memory content and audiovisual encoding can change distractor handling, and that this differs between control participants and people with substance use disorder [4]. The spatial-cue work shows a suppression gradient but does not test memory [2]. No supplied study directly compares memory-guided and spatially guided suppression in the same participants, so the question of whether they share one suppression mechanism or use separate ones is not yet settled by this evidence.
Sources used in this answer
Erratum: Feldmann-Wüstefeld et al., “Spatially Guided Distractor Suppression during Visual Search”
This erratum corrects a figure labeling error in a study of spatially guided distractor suppression and does not itself examine memory-guided attention.
Spatially Guided Distractor Suppression during Visual Search
Behavioral and EEG data show a spatial gradient of distractor suppression: target selection improves and the distractor positivity declines monotonically as target-distractor distance increases, with suppressed theta-band activity at distractor positions.
Causal investigation of mid-frontal theta activity in memory guided visual search
In a single-blind sham-controlled between-subject design, mid-frontal theta stimulation modulated memory-guided visual search and distractor suppression, supporting a causal role for theta activity.
The auditory stimulus facilitates memory guidance in distractor suppression in males with substance use disorder
In a working memory/visual search dual task, a memory sample matching a distractor's color sped responses in controls under visual-only conditions, and congruent auditory encoding produced comparable facilitation in both groups, appearing later in the substance-use-disorder group and larger than the visual-only effect.
Neural mechanisms underlying distractor suppression guided by spatial cues
Spatial cues produce proactive distractor suppression, with alpha lateralization linked to subsequent biomarkers of distractor suppression during visual search.