Perceptual Judgements of Plaid Motions Biased by Active Movements

The interpretation of a plaid stimulus moving through an aperture is inherently ambiguous. It can be perceived either as a coherent pattern moving rigidly or as two gratings sliding over each other. Perceptual uncertainty thresholds can be modulated by changing the relative luminance properties of single gratings. Many studies on action-perception transfer suggested that information required by the motor system to produce movements affects visual motion perception. We reasoned that physical interaction between an observer and the stimulus may influence the perceptual uncertainty associated to the moving plaids. Accordingly, we designed a motor task in which observers actively generate the relative movement between the plaid and the aperture. A two-alternative forced choice task was performed before and after the motor task to assess the motor effect on the perception of plaid motion. Preliminary results show that action biases the perceptual decision in a wide range of conditions and with spatial differences.