Both encountering cognitive conflicts and committing errors slow down performance. We investigated the development of the processes underlying post conflict slowing (PCS) and post error slowing (PES) in four age groups: 8-, 10-, 12- year old children and young adults. An initial strong slow down on the first post error trial reflected a reflexive reorientation to the error (automatic process) and contrasted the controlled steady slowing found on subsequent trials and after conflicts reflecting heightened cognitive control (controlled process). Interestingly, eight to ten year olds needed more time to recover from an error, as it is evident from the endurance of the automatic process over more than one trial. PCS and PES effects declined with age indicating less disturbance from errors and more efficient performance adjustments. The findings highlight the development and fine-tuning of cognitive control and are a further piece of evidence for the two process view of PES.
