Congruency proportion reveals asymmetric processing of irrelevant physical and numerical dimensions in the size congruity paradigm.

When the proportion of congruent trials in conflict tasks is manipulated (e.g., Stroop, Simon), the typical result is that the magnitude of the conflict effect increases as the proportion of congruent trials increases. The present experiment investigated the influence of Congruency Proportion in the context of the Size Congruity Paradigm. Congruency Proportion had a significant impact on the Numerical Judgement Task (judging which of two numbers is numerically larger), but not on the Physical Judgement Task (judging which of two numbers is printed in a larger font). These data support the inference that physical size information is processed before, and more fluently than, numerical size information. The implications of this asymmetry are discussed in terms of the relative role of semantic and physical size information in representations of magnitude, and the role they play in both of these tasks.