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Visual information and rubber hand embodiment differentially affect reach-to-grasp actions
Tobias Heed1, Michael Gründler, Jennifer Rinkleib
1Biological Psychology and Neuropsychology, University of Hamburg, von-Melle-Park 11, 20146 Hamburg, Germany. tobias.heed@uni-hamburg.de
Acta Psychologica
|July 27, 2011
Summary
The rubber hand illusion (RHI) alters perceived hand size and influences reaching actions. However, artificial hand size impacts grip aperture independently of the RHI, suggesting distinct processing pathways for perception and action.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Human Perception
Background:
- The rubber hand illusion (RHI) demonstrates multisensory integration, where tactile sensation from a real hand is attributed to a synchronously stroked artificial hand.
- Previous research presents mixed findings on whether the RHI affects motor actions, particularly hand movement and grasping.
- Understanding the RHI's impact on action processing is crucial for elucidating the relationship between perception and motor control.
Purpose of the Study:
- To investigate the influence of the RHI on perceived hand size and reach-to-grasp actions.
- To determine if artificial hand size affects the RHI's impact on motor execution.
- To differentiate the effects of embodiment and visual information on hand action during the RHI.
Main Methods:
- Participants underwent the RHI using artificial hands of varying sizes.
- Perceived hand size was assessed through subjective reports.
- Reach-to-grasp actions were measured, analyzing hand transport (reaching) errors and grip aperture.
- The influence of artificial hand size and RHI induction on these action parameters was statistically analyzed.
Main Results:
- Perceived hand size was significantly altered by the size of the artificial hand used in the RHI.
- Reach errors during a reach-to-grasp task were dependent on the perceived location of the hand, not the artificial hand size, during RHI.
- Grip aperture was influenced by the artificial hand's visual size, irrespective of RHI embodiment, indicating a separate visual processing effect.
Conclusions:
- The RHI modulates both perceptual experience (hand size) and action processing (reaching location).
- Motor control involves distinct mechanisms for processing perceived location (embodiment-dependent) and visual size information (embodiment-independent).
- Visual information about hand size influences grasping independently of the sense of embodiment generated by the RHI.
