Examining the costs and benefits of inhibition in memory retrieval.

Inhibitory control is thought to serve an adaptive function in controlling behavior, with individual differences predicting variation in numerous cognitive functions. However, inhibition is more properly construed as inducing both benefits and costs to performance. Benefits arise at the point when inhibition prevents expression of an unwanted or contextually inappropriate response; costs arise later, when access to the inhibited representation is required by other processes. Here we illustrate how failure to consider both the costs and benefits of inhibition has generated confusion in the literature on individual differences in cognitive control. Using retrieval-induced forgetting as a model case, we illustrate this by showing that changing the way that retrieval-induced forgetting is measured to allow greater expression of the benefits of inhibition together with the costs can reduce and even reverse the theoretically predicted correlation between motor and memory inhibition. Specifically, we show that when the final test in a retrieval-induced forgetting procedure employs item-specific cues (i.e., category-plus-stem cued recall and item-recognition) that better isolate the lingering costs of inhibition, better motor response inhibition (faster stop-signal reaction times) predicts greater retrieval-induced forgetting. In striking contrast, when the final test is less well controlled, allowing both the costs and benefits of inhibition to contribute, motor response inhibition has the opposite relationship with retrieval-induced forgetting. These findings underscore the importance of considering the correlated costs and benefits problem when studying individual differences in inhibitory control. More generally, they suggest that a shared inhibition mechanism may underlie people's ability to control memories and actions.