The heaviness of invisible objects: Predictive weight judgments from observed real and pantomimed grasps

- Observation of others' actions provides a shared experience of objects acted upon.
- Observation of grasping movements provides a shared experience of object weight.
- Object weight can be predictively judged from the kinematics of real grasps.
- Weight judgements are also possible from the observation of pantomimed grasps.

Observation of others' actions has been proposed to provide a shared experience of the properties of objects acted upon. We report results that suggest a similar form of shared experience may be gleaned from the observation of pantomimed grasps, i.e., grasps aimed at pretended objects. In a weight judgment task, participants were asked to observe a hand reaching towards and grasping either a real or imagined glass, and to predictively judge its weight. Results indicate that participants were able to discriminate whether the to-be-grasped glass was empty, and thus light, or full, and thus heavy. Worthy of further investigation, this finding suggests that by observing others' movements we can make predictions, and form expectations about the characteristics of objects that exist only in others' minds.