Learning and awareness in the serial reaction time task

This study examined evidence for implicit rule-based learning in the serial reaction time task and investigated the effect of explicit knowledge on performance. Participants responded to visual stimuli appearing in one of six locations. In each run, six stimuli were presented, with a stimulus appearing in each and every position exactly once in a random order. Participants implicitly learned the pattern as indicated by better performance on the sixth trials than on the first trials. Yet none of the three measures of explicit knowledge - verbalization, free generation, and recognition - were able to detect participants' awareness of the pattern. Explicit knowledge of the pattern improved performance, whereas active search for the pattern hurt performance if the pattern was not found. A possible learning mechanism is proposed to account for serial learning.