Recent studies on the probability cueing effect have shown that a spatial bias emerges toward a location where a target frequently appears. In the present study, we explored whether such spatial bias can be flexibly shifted when the target-frequent location changes depending on the given context. In four consecutive experiments, participants performed a visual search task within two distinct contexts that predicted the visual quadrant that was more likely to contain a target. We found that spatial attention was equally biased toward two target-frequent quadrants, regardless of context (context-independent spatial bias), when the context information was not mandatory for accurate visual search. Conversely, when the context became critical for the visual search task, the spatial bias shifted significantly more to the target-frequent quadrant predicted by the given context (context-specific spatial bias). These results show that the task relevance of context determines whether probabilistic knowledge can be learned flexibly in a context-specific manner.

Learning environmental regularities allows us to make predictions and guide behavior. Growing evidence of location probability learning (LPL) has shown that the statistical regularity of target locations affects spatial attention allocation. However, past studies on LPL have mostly focused on adults’ learning. To achieve a comprehensive understanding of the mechanism of this learning, we investigated the effect of target location probability on 5- to 9-year-old children’s visual search in comparison with that of adults. Both children and adults responded faster when the target appeared in the high probability “rich” quadrant than in the low probability “sparse” quadrants of the search space. This attentional bias toward the rich quadrant persisted even when the target was equally likely to appear in all four quadrants. Importantly, the magnitude of the bias was constant across various ages of participants and did not depend on individual differences in executive functions. Taken together, these results provide novel and converging evidence that implicit statistical learning of target locations occurs early in development and remains stable until early adulthood, which is a distinct developmental pattern from explicit goal-driven spatial attention learning.

Statistical knowledge of a target’s location may benefit visual search, and rapidly understanding the changes in regularity would increase the adaptability in visual search situations where fast and accurate performance is required. The current study tested the sources of statistical knowledge—explicitly-given instruction or experience-driven learning—and whether they affect the speed and location spatial attention is guided. Participants performed a visual search task with a statistical regularity to bias one quadrant (“old-rich” condition) in the training phase, followed by another quadrant (“new-rich” condition) in the switching phase. The “instruction” group was explicitly instructed on the regularity, whereas the “no-instruction” group was not. It was expected that the instruction group would rely on goal-driven attention (using regularities with explicit top-down knowledge), and the no-instruction group would rely on habit-like attention (learning regularities through repetitive experiences) in visual search. Compared with the no-instruction group, the instruction group readjusted spatial attention following the regularity switch more rapidly. The instruction group showed greater attentional bias toward the new-rich quadrant than the old-rich quadrant; however, the no-instruction group showed a similar extent of attentional bias to two rich quadrants. The current study suggests that the source of statistical knowledge can affect attentional allocation. Moreover, habit-like attention, a different type of attentional source than goal-driven attention, is relatively implicit and inflexible.

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The visual system can learn statistical regularities and form search habits that guide attention to a region where a target frequently appears. Although regularities in the real world can change over time, little is known about how such changes affect habit learning. Using a location probability learning task, we demonstrated that a constant target location probability resulted in a long-term habit-like attentional bias to the target-frequent location. However, when the target probability changed over time in any pattern, the same amount of learning induced only a short-term bias and disrupted the formation of long-term search habits. Moreover, although temporal changes in regularity during initial learning interfered with the acquisition of a search habit, they did not modulate the already consolidated bias. These results suggest that the stability and flexibility of habitual attention learning depend on when and how the statistical regularities in the environment change.