Tracking the implicit acquisition of nonadjacent transitional probabilities by ERPs

Abstract

The implicit acquisition of complex probabilistic regularities has been found to be crucial in numerous automatized cognitive abilities, including language processing and associative learning. However, the neurocognitive processes supporting the implicit extraction of 2nd order non-adjacent transitional probabilities have not been completely elucidated. Therefore, this study investigated the sensitivity of event-related brain potentials (ERPs) to these probabilistic regularities embedded in a sequence of visual stimuli without providing explicit information on the structure of the stimulus stream. Healthy young adults (N = 32) performed a perceptual-motor RT task that included an alternating sequential regularity between non-adjacent trials while RTs and ERPs were measured time-locked to the onset of the stimulus. RT effects indicated the rapid acquisition of transitional probabilities. The acquisition process was also tracked by the P3 component. Modulations of the P3 amplitude indicated that the more probable short-range relations could be integrated in the internal representations formed on the experienced stimulus environment. Meanwhile, the less probable short-range relations delivered possibly surprising information over the course of the task, by which the internal representations could have been updated. These results suggest that representations on the probabilistic regularities of the ongoing stimulus context are implicitly formed and constantly revised. Overall, this study (1) highlights the role of predictive processes during implicit memory formation, and (2) delineates a potential to gain further insight into the dynamics of implicit acquisition processes