The Rubber Hand Illusion - Research Paper Example

A screen was placed between the arm and the subject so that the arm would be hidden from the subject’s sight. A rubber hand was placed where the left hand would normally lay in the line of sight, and subjects focused on this artificial appendage while it and their real left hand were simultaneously stroked with a paintbrush.

Subjects reported their experience through an open-ended questionnaire, and it was widely stated that the brush strokes were felt as if they were coming from the rubber arm. This study spawned a large interest in the implications and mechanisms of the RHI that continues into the second decade of the new millennium. Nature of the Illusion A principle components analysis (Longo, Schuur, Kammers, Tsakiris, & Haggard, 2008) revealed that the experience of the embodied rubber hand during the RHI could be categorized into four components.

Subjects experience the rubber hand as a part of their own body (including ownership, location, and agency), the loss of their own hand, and movement in the rubber hand, and they also experience affective (emotional) qualities of the RHI. This perspective is supported by many subjective recounts of being under the illusion. Three distinct sensory modalities are involved in the RHI. Vision has proven to be the dominant force in a three-way relationship with touch and proprioception. The result of this multisensory integration process is a whole-self experience including the rubber hand (Tsarkis & Haggard, 2005).

The connectivity and complete sensory projection upon the false hand (as opposed to just on the spot where the brush was touching) are characteristics of the RHI that support the bodily-self component of the experience. Necessary Conditions The RHI occurs when visual, tactile, and proprioceptive stimuli combine to affect the multimodal integration process in a manner that causes the incorporation of the rubber hand into the body-self schema. Several conditions must be met in order for the illusion to take place.

The hand must be visually similar to an actual hand, though it does not have to be completely realistic. The visual position is the dominant sense in the production of the RHI, but sufficiently compliant tactile and proprioceptive information must also be presented (for example, brush strokes must be synchronous). Possible Adaptive Role The relatively late discovery of the RHI may be due to the covert nature of multisensory integration. This effect may support such important adaptations as tool use by making tools “feel” as though they are a part of the bodily self.

The processes may also be involved in providing feedback throughout the senses of touch, vision, and proprioception, and thereby allowing easier incorporation of clothing, accessories, and near environment into the structure of the body schema. A more recent adaptive role of the RHI is found in the incorporation of prosthetics into a new amputee’s sense of bodily self.