How reinforcement shapes the binding of stimulus-control associations
Cognitive control describes the ability to use internal goals to strategically guide how we process and respond to our environment. Changes in the environment lead to adaptation in control strategies. This type of control-learning can be observed in performance adjustments in response to varying proportions of easy to hard trials over blocks of trials on classic cognitive control tasks. Known as the list-wide proportion congruent (LWPC) effect, here, increased difficulty is met with enhanced attentional control. Recent research has shown that reinforcement events, in the form of performance feedback, enhance the LWPC effect, but the underlying mechanisms are not yet understood. To assess different hypotheses of how feedback is processed in the LWPC, we manipulated proportion congruency in a Stroop task over blocks of trials and provided trial-by-trial task-relevant word and task-irrelevant, trial-unique image performance feedback. The LWPC task was followed by a surprise recognition memory task for feedback images, which allowed us to test whether attention to feedback (incidental memory for the images) varies as a function of proportion congruency, time, and individual differences in reward sensitivity. We replicated a robust LWPC effect. Importantly, the memory data revealed better encoding of feedback images from context-defining trials (e.g., congruent trials in a mostly congruent block), especially early on in a new context, and in congruent conditions. Individual differences in reward sensitivity were not strongly associated with control-learning effects. These results suggest that reinforcement promotes the rapid forming of associations between stimuli and control demands, or context binding.