Abstract
Every day, we interact with people synchronously, immediately understand what they are doing, and easily infer information about their mental state and the likely outcome of their action from their kinematics. According to motor theories of perception, such efficient perceptual processing of others’ actions is achieved within the motor system by a process of “motor simulation”, i.e., an unconscious covert imitation of the observed movements. On this hypothesis, individuals incapable of simulating observed movements in their motor system should have difficulties perceiving and interpreting observed actions. Contrary to this prediction, we found across eight sensitive experiments that five individuals born without upper limbs (i.e., upper limb dysmelia) perceived, anticipated, predicted, comprehended and memorized upper limb actions (i.e., that they cannot simulate) as accurately and as rapidly as age- and education- matched typically developed participants. We also found that, like the typically developed participants, the dysmelic participants systematically perceived the position of moving upper limbs slightly ahead of their real position but only when the anticipated position would be biomechanically possible. Such anticipatory bias and its modulation by implicit knowledge of the body biomechanical constraints were previously considered as indexes of motor contribution to perception. Our findings undermine this assumption and, together, show instead that efficient action perception does not rely on a motor simulation process.
Meeting abstract presented at VSS 2015