The grasping side of post-error slowing.

A common finding across many speeded reaction time (RT) tasks is that people tend to respond more slowly after making an error. This phenomenon, known as post-error slowing (PES), has been traditionally hypothesized to reflect a strategic increase in response caution, aimed at preventing the occurrence of new errors. However, this interpretation of PES has been challenged on multiple fronts. Firstly, recent investigations have suggested that errors may produce a decrement in performance accuracy and that PES might occur because error processing has a detrimental effect on subsequent information processing. Secondly, previous research has been criticized because of the limited ecological validity of speeded RT tasks. In the present study, we investigated error-reactivity in the context of goal-directed actions, in order to examine the extent to which PES effects impact on realistic and complex movements. Specifically, we investigated the effect of errors on the reach to grasp movement (Experiment 1). In addition to RTs, we performed a kinematical analysis in order to explore the underlying reorganization of the movements after an error. The results of the present study showed that error reactivity strategically influences the grasping component of the action, whereas the reaching component appears to be impermeable to PES. The resistance of the reaching component to PES was confirmed in a second 'only reaching' experiment (Experiment 2). These finding supports the hypothesis that error reactivity is a flexible process whose effects on behavior also depend on the motor components involved in the action.