Statistical learning of spatiotemporal target regularities in the absence of saliency.

In previous studies, it was established that individuals can implicitly learn spatiotemporal regularities related to how the distribution of target locations unfolds across the time course of a single trial. However, these regularities were tied to the appearance of salient targets that are known to capture attention in a bottom-up way. The current study investigated whether the saliency of target is necessary for this type of learning to occur. In a visual search task, participants were instructed to search for a unique circle with a gap (Landolt C) among two other circles and indicate the location of the gap. Unbeknownst to them, the onset timing of search displays predicted the target location. Specifically, the target appeared more frequently at one peripheral location with an early onset of the search display and at the opposite peripheral location with a late onset of the search display. Additionally, we manipulated the gap size of the Landolt C to create either nonsalient (small gap) or salient (big gap) target events. Results showed that, regardless of prior exposure to salient targets (Experiment 1) or nonsalient targets (Experiment 2), visual search efficiency increased when the target appeared at the temporally valid location compared with the temporally invalid location. In conclusion, the saliency of targets and the associated bottom-up capture is not a prerequisite for learning dynamic distributional regularities of target locations during visual search.