Repeated contexts yield faster response time in visual search, compared with novel contexts. This effect is known as contextual cueing. Despite extensive study over the past two decades, there remains a spirited debate over whether repeated displays expedite search before the target is found (early locus) or facilitate response after the target is found (late locus). Here, we provide a tutorial review of contextual cueing, with a focus on assessing the locus of the effect. We evaluate the evidence from psychophysics, EEG, and eye tracking. Existing studies support an early locus of contextual cueing, consistent with attentional guidance accounts. Evidence for a late locus exists, though it is less conclusive. Existing literature also highlights a distinction between habit-guided attention learned through experience and changes in spatial priority driven by task goals and stimulus salience.

Frequently finding a visual search target in one region of space induces a spatial attentional bias toward that region. Past studies on this effect typically tested fewer than 20 participants. The small sample prevents an investigation of two properties of learning: visual field uniformity and role of explicit awareness. Pooling data from multiple studies, here we examined location probability learning from ~120,000 visual search trials across 420 participants. Participants performed a serial search task. Unbeknownst to them, the target was disproportionately likely to appear in one visual quadrant. Location probability learning (LPL) was measured as the difference in reaction time to targets in the high-probability "rich" quadrant and the low-probability "sparse" quadrants. Results showed a lack of visual field effect. LPL was equivalent for "rich" quadrant in the upper left, upper right, lower left, and lower right. Learning did not induce a hotspot diagonal to the "rich" quadrant. To the contrary, RT was the longest in the diagonal quadrant. Recognition rate of the "rich" quadrant was above chance. However, recognition accuracy was unrelated to the size of LPL. Implicit learning induces visual-field-independent changes in spatial attention.

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Under continuous dual-task conditions, participants show better memory for background information appearing at the same time as a response target in a concurrent task than for information appearing with a nontarget (the attentional boost effect, or ABE). While this effect has been demonstrated across a wide range of stimuli, few studies have examined the perceptual specificity of the memory difference. Here, we explored whether the ABE affects general category memory or perceptually specific exemplar memory. In an encoding phase, participants memorized images of objects presented in a continuous stream. At the same time, they pressed the space bar when a square appearing in the center of each image appeared in a target color, ignoring distractorcolored squares. The following four-alternative forced-choice memory test included the previously seen image, a perceptually distinct exemplar from the same category as the previously seen image, and two images from a new category. Regardless of whether images appeared during encoding three times (Experiment 1) or once (Experiment 2), participants recognized the correct exemplar more often during testing for images that had appeared with a target in encoding than for images that had appeared with a distractor. The difference in exemplar memory was not associated with a difference in false memories for within-category foils. This suggests that the ABE reflects modulation of perceptually detailed exemplar memory, which may be related to facilitation of pattern separation by detection-induced changes in cortical-hippocampal connectivity.

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