Both trace and delay conditioning of evaluative responses depend on contingency awareness

Whereas previous evaluative conditioning (EC) studies produced inconsistent results concerning the role of contingency knowledge, there are classical eye-blink conditioning studies suggesting that declarative processes are involved in trace conditioning but not in delay conditioning. In two EC experiments pairing neutral sounds (conditioned stimuli; CSs) with affective pictures (unconditioned stimuli; USs), we tested whether the type of conditioning procedure affects the relationship between awareness and EC. Auditory CSs and visual USs were either overlapping and co-terminating (Delay Conditioning Group), or they were separated by a short temporal gap (Trace Conditioning Group). In both groups, contingency awareness was manipulated by varying the duration at which the US was presented during conditioning. Furthermore, in addition to a post-conditioning measure of awareness, US detectability was measured concurrently during the learning phase in Experiment 2. US exposure duration affected both measures of awareness. The data of both experiments demonstrate that EC does not occur if the USs are presented at very brief durations, but reliable EC effects can be observed at longer US exposure durations. As there were no differences between trace and delay conditioning, the data suggest that contingency awareness plays a crucial role in trace and in delay conditioning of evaluative responses. These results challenge automatic association-formation accounts of EC, but they are in line with ‘single-process’ accounts assuming EC to be dependent on conscious declarative knowledge about CS–US contingencies.