Temporal Structure Modulates ERP Correlates of Visual Sequential Learning

Sequential learning (SL) refers to the ability to learn the temporal and ordinal patterns of one’s environment. Whereas research on the learning of ordinal patterns is common, the learning of temporal patterns within sequential events has been far less studied. The current study examines the effects of synchronous and asynchronous temporal patterns on visual sequential learning. We hypothesize that entrainment (i.e. exposure to a regular rhythmic pattern) allows for better processing of the ordinal structure of sequential events. Twenty healthy adult participants (11 females, 18–34 years old) performed two versions of a visual sequential learning paradigm while event-related potentials (ERPs) were recorded. The SL task involved the visual presentation of colored circles, wherein a target circle was embedded that was partially predictable based on preceding predictor stimuli. One version of the task incorporated synchronous temporal presentation of the stimuli whereas the other version involved asynchronous presentation of stimuli using a randomized ISI on every trial. Reaction time data demonstrated that learning occurred in both temporal conditions. On the other hand, the mean ERP amplitudes between 350 and 750ms post-predictor onset in the posterior regions of interest revealed that learning of the statistical contingencies between stimuli was disrupted for the asynchronous temporal condition but intact for the synchronous condition. These neurophysiological data suggest that the brain processes regular and irregular timing events differently, with statistical learning of ordinal visual patterns being improved by a synchronous temporal structure, possibly a result of heightened attention to the stimuli due to entrainment.