The dynamics of statistical learning in visual search and its interaction with salience processing: an EEG study (v1)

Visual attention can be guided by statistical regularities in the environment, that people implicitly learn from past experiences (statistical learning, SL). Moreover, a perceptually salient element can automatically capture attention, gaining processing priority through a bottom-up attentional control mechanism. Here we investigated the dynamics of SL and its interplay with bottom-up control during target selection processing. In a visual search task we manipulated target frequency (high/low) across locations and the saliency of target in terms of colour (salient/no-salient). Halfway through the experiment, the high-frequency location changed to the opposite hemifield. EEG activity was recorded to assess two markers related to target selection and post-selection processing, respectively: N2pc and SPCN. Results revealed that SL and saliency enhanced behavioural performance, but also interacted with each other, with an attenuated saliency effect at the high-frequency target location, and a smaller SL effect for salient targets. Concerning processing dynamics, the benefit of bottom-up control was more evident during the early stage of target selection and processing, as indexed by a larger N2pc and early-SPCN, whereas SL modulated the underlying neural activity particularly later on, as revealed by larger late-SPCN. Furthermore, we showed that SL was rapidly acquired and adjusted when the spatial imbalance changed. Overall, our findings suggest that SL is flexible to changes and jointly contributes with bottom-up control to establishing attentional priority.