Abstract
The perceived sequence of events does not always match to their real temporal order. Previous studies have demonstrated that a numerically smaller digit was perceived as appearing earlier than was a large digit when they were simultaneously presented. However, it is disputed whether the temporal advantage of small numbers is due to a faster perceptual processing of small digits or simply reflects a response bias for small numbers. We conducted two experiments to address this issue. A pair of digits (one small and the other large in magnitude) was briefly presented (50 ms) side-by-side on the screen with a stimulus-onset asynchrony varied from -50 to 50 ms. In Experiment 1, we used a temporal order judgment task in which participants judged the side from which a digit appeared first. Numerical magnitude was irrelevant to the task. The point of subjective simultaneity (PSS) was estimated by adopting a curve-fitting procedure. Consistent with previous reports, the PSS was significantly shifted toward the condition that large digits were presented first, so simultaneity could be perceived only if the large digit came slightly before (7 ms) the small digit. This result supports the argument that there is temporal advantage for small numbers during perceptual processing. However, this advantage might simply be due to a response bias for small numbers. To exclude the potential influence of response bias, in Experiment 2, we adopted a simultaneity judgment task in which the participants judged whether the two digits were presented simultaneously or successively. The result indicated that the maximal possibility of simultaneous response was obtained when large digit preceded small digit by 5 ms, suggesting again that small numbers are processed faster than large numbers. Our finding indicates that small numbers are perceived earlier than larger numbers, and that perceptual mechanisms contribute to this temporal advantage.
Meeting abstract presented at VSS 2014