Planning: fixed-foreperiod event-related potentials during the Tower of London task.

Slow wave ERPs were recorded from 28 young adults as they generated plans for various difficulty levels of a fixed-foreperiod version of the Tower of London task. The resulting waveform included three segments: (1) a left-lateralized negative early-interval wave, which was frontally maximal but not sensitive to difficulty, (2) a right-lateralized frontally maximal mid-interval wave, which was more positive for more difficult problems, and (3) a left lateralized centrally maximal negative-ramping contingent negative variation (CNV) late wave, which was more negative for more difficult problems. The current study adds to the current literature in that it finds that the frontal and central neural utilization with difficulty changes across plan generation. This suggests that plan generation should be considered in terms of when component processes of planning are differentially utilized as plan generation unfolds.