The size-weight illusion in a natural and augmented environment with congruent and incongruent size information

The size-weight illusion (SWI) occurs when the smaller of equally weighted objects is judged to feel heavier than the larger object. Experiment 1 compared the SWI generated in a natural versus augmented-reality environment while grasping and lifting three differently sized cubes of equal weight. Both environments induced the SWI for all twenty participants. Lift kinematics covariedwith cube size in both environments. Experiment 2 investigated the influence of incongruent visual size information on the SWI in an augmented environment. Physical cubes were paired with three graphical representations: a smaller, an equal-sized, and a larger cube. The SWI was influenced by both haptic and visual size information. Kinematics covariedwith physical size throughout the experiment. Results suggest that vision significantly impacts the bimodal SWI when haptic and visual size information is not redundant. Results have implications for theories of heaviness perception, multimodal interaction, and perception and action in augmented environments.