Visual similarity and memory in body model distortions
The ability to localise our own body in space is crucial for perception and action. Localisation judgments related to our body parts are based on a combination of both proprioceptive signals and stored representation of body size and shape.
However, perception of one’s own hand is distorted in proprioceptive localisation tasks – it appears fatter and shorter, with the fingers perceived as progressively shorter moving laterally. These distortions are thought to mirror somatosensory anisotropies.
Recent studies have questioned whether such distortions were specific to the human body? The aim of the current study was to investigate the influences of visual similarity and memory on the distortions observed in the real hand, a rubber hand and a rake.
Three separate experiments were conducted: 1) a localisation task; 2) a distance memory task; and 3) memory vs. feeling.
Experiment 1 showed that the participants’ hands were significantly more distorted in comparison to a rubber hand and a rake (hand-like object). Experiment 2 suggested that memory cannot fully account for the distortions observed in experiment 1. Experiment 3 indicates that the aforementioned distortions in the body’s representation of the hand are due to somatosensation instead of memory-biases.
In essence, these findings suggest that the systematic hand distortions observed in the localisation task reflect an implicit body representation rather than an artefact of visual and memory confounders.