The Arm’s Blind Line: Anisotropic Distortion in Perceived Orientation of Stimuli on the Arm

Abstract

Given that mechanoreceptors are highly heterogeneously distributed and there is no direct sensory signal of the distribution, it must be challenging for the brain to identify stimuli in external space by remapping sensory inputs. Some previous studies reported perceptual distortion of tactile space, reflecting a difference in scales for different body parts. Here we report another example in which the orientation of stimuli perceived on the arm is rotated regionally, or even flipped. This illusion cannot be explained simply in terms of the resolution difference of mechanoreceptors.