Numbness Illusion in Autism: Implications for Social Interactions

The aim of current research was to examine the multisensory nature of body ownership (i.e., the sense of our body belong to us) in individuals with Autistic Spectrum Disorder (ASD) by using a procedure based on tactile conflicts, namely the numbness illusion (NI). The NI is a paradigm involving tactile and proprioceptive stimulation that induces an unreal sense of property for another person’s finger. The NI occurs when one person places his/her palm against another person's opposite palm and strokes the two joint index fingers with the other hand synchronously. When the stroking is asynchronous the NI is usually reduced or absent. Results suggest that individuals with ASD were more susceptible to the NI than controls, indicating that the illusion occurred independently of the type of stroking. These findings suggested an anomalous sense of finger ownership in individuals with ASD that may be related to a wide range of sensory dysfunctions. In turn, this might have implications at the level of social interactions.