Lower limb peripersonal space and the desire to amputate a leg

Ownership of the affected leg is further reduced following deceptive behaviors in body integrity dysphoria

Although predicted by the notion of embodied morality, it remains unknown whether a reduced sense of body ownership (SoO) is associated with increased or decreased dishonesty. To clarify this issue, we tested patients with body integrity dysphoria (BID), a clinical condition characterized by chronic reductions of SoO toward one leg that patients persistently desire to have amputated. Participants with BID played a card game in which they could voluntarily tell the truth or cheat an opponent, and thus either steal or give them money. To assess whether SoO toward the effector limb influences (im)moral decisions, responses were communicated with the affected or the unaffected leg. We found that a higher number of self-gain lies was followed by further reductions of SoO toward the affected leg. Our result supports the idea that reductions of SoO may follow immoral behaviors to distance from unwanted characteristics of the self, like one's own dishonesty.

Is this my foot? Experimentally induced disownership in individuals with body integrity dysphoria

In body integrity dysphoria (BID), otherwise healthy individuals feel like a part of their physical body does not belong to them despite normal sensorimotor functioning. Theoretical and empirical evidence suggested aweakened integration of the affected body part into higher-order multisensory cortical body networks. Here, we used a multisensory stimulation paradigm in mixed reality to modulate and investigate multisensory processing underlying body (dis)ownership in individuals with BID of the lower limb. In 20 participants with BID, delay perception and body ownership were measured after introducing delays between the visual and tactile information of viewed stroking applied to affected and unaffected body parts. Unlike predicted, delay perception did not differ between the two body parts. However, specifically for the affected limb, ownership was lower and more strongly modulated by delay. These findings might be following the idea of a stronger dependency on online bottom up sensory signals in BID.