Size Matters: Non-Numerical Magnitude affects the Spatial Coding of Response

It is known that small and large numbers facilitate left/right respectively (the SNAR effect). Recently, it has been proposed that numerical magnitude is just one example of a range of quantitites, which have a common cognitive/neural representation. To investigate this proposition, response congruency effects were explored for stimuli which differed accoding to their: (a) numerical size, (b) physical size, (c) luminance, (d) conceptual size and (e) auditory eintensity. In a series of experiments, groups of undergraduate participants made two-alternative forced choice discriminiations with their left or right hands. There were clear interactions between magnitude and responding hand whereby rught hand responcses were faster for stimuli with (a) large numbers, (b) large physical size, (c) low luminance, and (d) a refernce to large objeects. There was no congruency effect for the auditory stimuli. The data demonstrate that the response congruency effect observed for numbers also occurs for a variety of other of non-numerical visual quntities. These results support model of general magnitude representation and suggest that the association between magnitude and the left/right sides of space may not be related to culture and/or directional reading habits.