Associations Between Physical Stimulus Size and Vertical Response Locations

This study investigates the existence and direction of associations between physical stimulus size and vertical response locations. In Experiment 1, 80 participants responded to stimulus size by pressing one of two vertically arranged keys. We orthogonally manipulated within-subjects the mappings between stimulus size and response-key locations, and between hands and response keys. The results showed a novel compatibility effect between physical stimulus size and vertical response location: Responses to the small stimulus were faster at the lower than at the higher location, whereas responses to the large stimulus were faster at the higher than at the lower location. In Experiment 2, we replicated this compatibility effect in vocal responses, when 66 participants responded to stimulus size by saying location words. In combination with previous findings, the present results suggest that the physical size of visual objects is not only associated with horizontal locations but also with vertical locations. These associations presumably reflect learned correlations between the size of objects and their extension in both the horizontal and the vertical direction. Moreover, the observation of size-space compatibility effects in vocal responses may indicate that they do not only reflect sensorimotor experiences but also semantic knowledge, which is expressed in linguistic metaphors.