Different effects of spatial separation in action and perception.

Spatial distance of response keys has been shown to have an effect on nonspatial tasks in that performance improved if the spatial distance increased. Comparably, spatial distance of stimulus features has been shown to have a performance-improving effect in a (partly) spatial task. Here, we combined these two findings in the same task to test for the commonality of the effect of stimulus distance and the effect of response distance. Thus, we varied spatial distance in exactly the same fashion either between stimuli or between responses in a standard Eriksen flanker task. The results show that spatial distance only affected the processing of stimulus features, while it had no effect on the processing of response features. Regarding the idea of common coding of action and perception (Prinz, 1990), stimulus and response processing should be influenced by spatial distance in the same way so that our data might suggest a boundary for the idea of common coding.