Response-repetition effects in task switching - dissociating effects of anatomical and spatial response discriminability

In task switching, response repetitions typically lead to performance benefits for task repetitions but costs for task switches. We examined whether this cost–benefit pattern is affected by response discriminability (RD), varying (a) the anatomical response separation (within-hand vs. between-hand responses) and (b) the spatial separation (close vs. far response keys). We assumed that anatomical RD increases response competition generally, whereas spatial RD increases the salience of left–right coding and thus facilitates response selection. In two experiments, we found that spatial RD increased the response-repetition costs in task switches but similarly decreased the response-repetition benefit in task repetitions. The effect of spatial RD was response-specific but did not interact with task switching. This data pattern is consistent with a recent account that proposed that facilitated response selection increases response “self-inhibition” after response execution. In contrast, the influence of anatomical RD primarily consisted of an overall increase of reaction-time level in all conditions, whereas error rates decreased, suggesting a general shift in response criterion. Taken together, the data suggest that a self-inhibition mechanism on the level of motor response codes contributes to response-repetition effects in task switching, which is possibly independent of task-specific mechanisms of strengthening of associations.     

On observing another person's actions: influences of observed inhibition and errors

It was investigated whether an observer would simulate another person's inhibitory and error processes. Two participants sitting next to each other performed a stop signal task in which they occasionally had to try and inhibit their response when indicated to do so by a stop signal. They could either successfully stop the response or fail to stop and, thereby, make an error. An aftereffect of the other person's successful action inhibition and error was obtained: The participants became slower and more accurate when they observed the other person make an error on the previous trial and when they observed a successful stop. The results suggest that observing another person successfully inhibit an action or make an error evokes processes similar to those that occur when these behaviors are produced.     

On observing another person’s actions: Influences of observed inhibition and errors

It was investigated whether an observer would simulate another person’s inhibitory and error processes. Two participants sitting next to each other performed a stop signal task in which they occasionally had to try and inhibit their response when indicated to do so by a stop signal. They could either successfully stop the response or fail to stop and, thereby, make an error. An aftereffect of the other person’s successful action inhibition and error was obtained: The participants became slower and more accurate when they observed the other person make an error on the previous trial and when they observed a successful stop. The results suggest that observing another person successfully inhibit an action or make an error evokes processes similar to those that occur when these behaviors are produced.