Execution-based and verbal code-based stimulus-response associations: proportion manipulations reveal conflict adaptation processes in item-specific priming.

Stimulus-response (S-R) associations consist of two independent components: Stimulus-classification (S-C) and stimulus-action (S-A) associations. Here, we examined whether these S-C and S-A associations were modulated by cognitive control operations. In two item-specific priming experiments, we systematically manipulated the proportion of trials in which item-specific S-C and/or S-A mappings repeated or switched between the single encoding (prime) and single retrieval (probe) instance of each stimulus (i.e., each stimulus appeared only twice). Thus, we assessed the influence of a list-level proportion switch manipulation on the strength of item-specific S-C and S-A associations. Participants responded slower and committed more errors when item-specific S-C or S-A mappings switched rather than repeated between prime and probe (i.e., S-C/S-A switch effects). S-C switch effects were larger when S-C repetitions rather than switches were frequent on the list-level. Similarly, S-A switch effects were modulated by S-A switch proportion. Most importantly, our findings rule out contingency learning and temporal learning as explanations of the observed results and point towards a conflict adaptation mechanism that selectively adapts the encoding and/or retrieval for each S-R component. Finally, we outline how cognitive control over S-R associations operates in the context of item-specific priming.