The effects of magnitude on visually guided action and perception.

Recent research has established the role of objects' semantic properties in the planning of motor actions with respect to these objects. It has been shown that visual magnitude affects visuomotor control in a similar direction to the effect of physical size: Larger magnitudes lead to larger grip apertures during grasping, even when physical size remains invariant. Despite the growing literature regarding this effect, little evidence has been gathered as for the way magnitude processing affects the visual perception of object's size. To address this issue, we presented participants with different representations of magnitude across both the auditory and the visual modalities, while asking them to either grasp a neutral object (action), or perform manual estimation of the object's size (perception). In Experiment 1, longer durations of an auditory stimulus led to larger grasping apertures during grasping, while manual estimations were not affected by the presented stimulus duration. When numerical magnitude information was conveyed visually (Experiment 2), this distinction became less prominent. Overall, these results lend further support for the idea that a common mechanism mediates visuomotor control and the processing of magnitude across different domains. Meeting abstract presented at VSS 2016