Defining stimulus representation in stimulus-response associations formed on the basis of task execution and verbal codes.

Responding to stimuli leads to the formation of stimulus-response (S-R) associations that allow stimuli to subsequently automatically trigger associated responses. A recent study has shown that S-R associations are established not only by active task execution, but also by the simultaneous presentation of stimuli and verbal codes denoting responses in the absence of own action [Pfeuffer et al. (Journal of Experimental Psychology: Human Perception and Performance 43:328-347, 2017)]. Here, we used an item-specific priming paradigm to investigate whether the stimulus part of S-R associations formed based on task execution and verbal codes is represented in abstract or specific format by examining whether S-R associations are retrieved for perceptually different forms of the same stimulus or not. Between the prime and probe instance of a stimulus, its format switched from image to word or vice versa. We found that, irrespective of whether stimuli were primed by task execution or verbal coding, performance was impaired when S-R mappings switched rather than repeated between the prime and probe instance of a stimulus. The finding that prime S-R mappings affected probe performance even when stimulus format switched indicates that stimuli were represented in abstract form in S-R association based on both task execution and verbal coding. Furthermore, we found no performance benefits for stimuli primed and probed in the same format rather than different formats, suggesting that stimuli were not additionally represented in specific format. Overall, our findings demonstrate the adaptability of automatized behaviors and indicate that abstract stimulus representations allow S-R associations to generalize across perceptually different stimulus formats.