Virtual Reality Reveals How Pain Disrupts Body Ownership – and Offers Hope for Depersonalization Treatment
The fundamental sense of body ownership – the intuitive feeling that this body is mine – is critical for navigating the world and responding to danger. But what happens when that sense is disrupted? New research from Hiroshima University, published in Frontiers in Psychology in December 2024, sheds light on how negative physical states and pre-existing psychological tendencies can weaken our connection to our bodies, offering potential insights into conditions like depersonalization.
Researchers have long explored body ownership using illusions like the rubber hand illusion (RHI) and the full-body illusion (FBI). These techniques cleverly exploit the brain’s ability to integrate sensory details, leading individuals to perceive a fake or virtual body as their own. The Hiroshima University study builds on this foundation,investigating how deliberately introducing a negative physical experience within a virtual reality (VR) environment impacts this sense of ownership.
how the Study worked: Combining Bottom-Up and Top-Down Processing
The study leveraged the power of VR to create a compelling full-body illusion. participants wore a VR headset and viewed a virtual body from behind, instructed to imagine it as their own. Crucially, the experiment combined “bottom-up” and “top-down” processing.
Bottom-up processing was initiated by synchronous tactile stimulation: participants felt gentle strokes on their own backs while simultaneously seeing the virtual body being stroked. This coordinated sensory input is a well-established method for inducing the FBI. top-down processing was introduced by instructing participants to imagine experiencing abdominal pain while identifying with the virtual body.This is where the study’s innovation lies - deliberately introducing a negative physical state before presenting a possibly threatening stimulus.
To gauge the strength of the illusion and the participant’s identification with the virtual body, researchers then presented a fear stimulus: a visual depiction of a knife entering the virtual body’s back. Physiological responses, specifically skin conductance, were measured to assess the level of fear experienced. A stronger fear response indicated a stronger sense of body ownership – the participant reacted as if the threat was directed at their body.
Pain and Depersonalization: A Clear Link Emerges
The results were striking. The researchers found that the full-body illusion was substantially inhibited when participants were asked to associate the virtual body with abdominal pain. Furthermore, individuals with a higher predisposition towards depersonalization – a feeling of detachment from one’s own body or reality – exhibited a weaker FBI overall.
This suggests a compelling link between negative physical states,pre-existing depersonalization tendencies,and the brain’s ability to establish body ownership. Researchers theorize that the discomfort may have interfered with the participant’s ability to fully integrate the visual and tactile information necessary for the illusion to take hold. In essence,the brain resisted accepting the virtual body as “mine” when simultaneously experiencing a negative sensation.Why This Matters: Implications for Clinical Intervention
“We observed this inhibitory effect, further research is needed to determine whether it was specifically due to the negative interpretation or to differences between actual and virtual body states,” explains Takashi Nakao, a researcher and author of the study. While further investigation is warranted, the findings have meaningful implications for understanding and potentially treating conditions characterized by disturbed body ownership, such as depersonalization-derealization disorder.The ability to manipulate and study body ownership in a controlled VR environment opens doors to developing targeted clinical interventions. By understanding how and why the sense of body ownership is disrupted, researchers can begin to design therapies aimed at strengthening this crucial connection.
Ultimately, restoring a strong sense of body ownership isn’t just about safety and threat detection; it’s about improving overall quality of life, enhancing sensory perception, and fostering a more grounded and integrated experience of self. This research represents a vital step towards achieving that goal.
