Learning modulates early encephalographic responses to distracting stimuli: a combined SSVEP and ERP study

Through experience, humans can learn to suppress locations that frequently contain distracting stimuli. However, the neural mechanism underlying learned suppression remains largely unknown. In this study, we combined steady-state visually evoked potentials (SSVEPs) with event-related potentials (ERPs) to investigate the mechanism behind statistically learned spatial suppression. Twenty-four male and female human participants performed a version of the additional singleton search task in which one location contained a distractor stimulus frequently. The search stimuli constantly flickered on-and-off the screen, resulting in steady state entrainment. Prior to search onset, no differences in the SSVEP response were found, though a post-hoc analysis did reveal proactive alpha lateralization. Following search onset, clear evoked differences in both the SSVEP and ERP signals emerged at the suppressed location relative to all other locations. Crucially, the early timing of these evoked modulations suggests that learned distractor suppression occurs at the initial stages of visual processing. Significance Statement Often times a distractor (e.g. a colorful yet irrelevant billboard on a highway) becomes easier to ignore after you’ve encountered it several times. This learned suppression is an important component of the human visual system which is otherwise highly salience driven. In a series of EEG experiments, we used SSVEPs and ERPs to study how learning changes attention towards salient distracting stimuli when these distractors appear frequently at specific locations. We found converging evidence that learning alters the early evoked responses to these stimuli. Our results indicate that through learning, early neural responses to distracting stimuli are changed.