Sticky Rules: Conjunctions between Rules and Stimulus-Response Codes Drive Action Selection
Atsushi Kikumoto1, Tesufuai Sameshima1, Ulrich Mayr1; 1University of Oregon
Action selection is often thought of as a hierarchical process, where high-level representations of abstract rules control lower-level stimulus or response selection. Theoretically, such control could occur in a strictly hierarchical manner, in which the rule representation plays no further role once it configures the relevant stimulus-response (S-R) links. Alternatively, rules may become integrated with lower-level settings and contextualize stimulus/response codes in a concurrent manner. To test these accounts, we decoded orthogonal, task-relevant dimensions (cues, rules, stimuli, and responses) from the spectral-temporal profile of the electrophysiological signal (EEG) during a task in which subjects had to select between different, abstract S-R rules on the basis of cues (Mayr & Bryck, 2005, JEP:LMC). Trial-by-trial information about the quality of each representation allowed time-resolved analyses of when and to what degree different representations are active and predict behavioral performance (RTs). Results showed that rules were active and predicted performance prior to stimulus presentation, suggesting that abstract rules can be established in a proactive manner. Yet, after stimulus onset, rules and specific stimulus and response codes were activated concurrently. Further, consistent with the integration account, conjunctive representations that combined rules and S-R codes emerged as a major predictor of performance, over and above rules or S-R codes by themselves. Thus, representations on different hierarchical levels do not function independently, but rather constrain each other to determine the appropriate response. These results demonstrate a powerful approach towards uncovering the cascade of representations that underlies action selection.
Topic Area: EXECUTIVE PROCESSES: Goal maintenance & switching