No evidence of consolidation of evaluative conditioning during waking rest and sleep

Research on evaluative conditioning (EC) shows that attitudes can emerge from co-occurrences of stimuli, and accumulating evidence suggests that EC usually depends on memory for these stimulus contingencies. Therefore, processes known to aid memory retention may be relevant for the development of stable attitudes. One such process may be memory consolidation, assumed to be promoted by waking rest and sleep. In two pre-registered experiments, we investigated whether waking rest (vs. cognitive activity, Experiment 1) and sleep (vs. wakefulness, Experiment 2) in between conditioning and measurement of EC, consolidate contingency memory and EC. Contrary to our predictions, waking rest (vs. cognitive activity) promoted neither contingency memory nor EC effects. Sleep (vs. wakefulness) decreased forgetting of contingency memory but crucially, it did not attenuate the impact of counterconditioning on contingency memory. Sleep also did not influence EC effects, nor the reduction of EC by counterconditioning. EC effects in both experiments were predicted by contingency memory. Yet, unexpectedly, EC effects occurred in the absence of contingency memory after waking rest, but neither after sleep nor in the active control conditions. Our findings emphasise a role of contingency memory in EC, but it remains unclear whether this role changes during waking rest.