The development of inhibitory control: an averaged and single-trial Lateralized Readiness Potential study.

Inhibitory control (IC) is an important contributor to educational performance, and undergoes rapid development in childhood. Age-related changes in IC were assessed using an in-depth analysis of reaction time, the Lateralized Readiness Potential (LRP), and other event-related potential (ERP) measures to control for speed of processing. Five-year-olds, 8-year-olds and adults completed an adapted Stroop task. Both reaction time and ERP results suggest that IC does develop in this age range, over and above changes in speed of processing. The LRP identified two processes that contribute to IC. These processes develop at different rates--an early process, involving how the conflict is initially responded to is mature by age 5, while a later process, involving how the conflict is overcome is still developing after 8 years of age. We propose that these early and late processes reflect interference suppression and response inhibition, respectively. Further, a single-trial analysis of the LRP in the incongruent condition provides evidence that the LRP is consistent across trials and functionally similar in each age group. These results corroborate previous findings regarding the development of IC, and present a new and useful tool for assessing IC across development.