Statistical learning (SL) of both target and distractor spatial probability distributions adjusts the attentional priority of locations. In the presence of a single manipulation for each location, SL also induces indirect effects (e.g., changes in filtering efficiency due to an uneven distribution of targets), suggesting that SL-induced plastic changes are implemented within common spatial priority maps. Here we tested whether, when target- and distractor-related manipulations are concurrently applied to the very same locations, dedicated mechanisms might support the independent encoding of spatial priority in relation to the attentional operation involved. In three related experiments, human healthy participants discriminated the direction of a target arrow, while ignoring a salient distractor, if present; target and distractor spatial probability distributions were systematically manipulated in relation to each single location. Critically, the selection bias produced by the target-related SL was significantly reduced by an adverse distractor contingency. Conversely, the suppression bias generated by the distractor-related SL was erased, or even reversed, by an adverse target contingency. Our results suggest that independent and concomitant target- and distractor-related SL manipulations concur to the plastic adjustment of the same spatial priority map(s), with the resulting priority corresponding to some kind of weighted average of the SL processes.
Spatial suppression due to statistical learning tracks the estimated spatial probability
