Spatial stimulus-response compatibility (SRC) refers to the robust finding that responses are faster and more accurate when stimulus and response locations are compatible (e.g., right stimulus-right key) than when they are incompatible (e.g., right stimulus-left key). However, a different pattern emerges with affectively valenced stimuli, such as flowers and spiders: When participants categorize stimuli as positive or negative, performance is better for positive-compatible and negative-incompatible stimulus-response mappings than vice versa, producing a reversed SRC effect for negative stimuli. This valence-by-compatibility interaction has been attributed either to approach/avoidance tendencies or to differences in the ease of selecting the specific stimulus-response mapping.

In the present study, we compared a valence-based Category-Compatibility Assignment Task (with flowers and spiders) with a same-different version of this task, in which participants responded based on whether two stimuli matched or mismatched in category, independent of valence. We observed a significant category-by-compatibility interaction in both tasks. Notably, the interaction was stronger in the same-different version, with comparable responses to pairs of flowers and pairs of spiders, demonstrating a remarkable lack of influence of affective valence.

Taken together, our results challenge the approach/avoidance account and instead suggest that spatial compatibility effects are primarily driven by the meaningful alignment between stimulus category and response mapping, rather than by the affective valence of the stimuli.