An illusion in which fake faeces are put on a rubber hand has been tested on people with obsessive compulsive disorder (OCD) (Jalal et al., 2020).

It may one day become a new treatment.

Therapies based on this illusion, designed to help people get more comfortable with germ exposure, could be less upsetting than existing therapies, says Baland Jalal at the University of Cambridge.

The original rubber hand illusion involves putting one hand out of sight and seeing a fake hand in its place. If someone else strokes both the fake and real hand, most people feel that the fake is their own.

Jalal and his colleagues tried a variant on people with hygiene-related OCD. They are usually treated with exposure therapy, but that would, for example, involve exposure on their actual hands. As a result, a quarter reject such therapy.

In the study, 29 people with OCD had fake faeces, made from foods and a fake odour, dabbed on the rubber hand, while their real, hidden hand was touched with a damp towel. While they knew the faeces were fake, they reported feeling disgusted and contaminated.

Jalal’s team plan to test the technique as a way of treating OCD.

References

Jalal, B., McNally, R.J., Elias, J.A., Potluri, S. & Ramanchandran, V.S. (2020) “Fake it till You Make it”! Contaminating Rubber Hands (“Multisensory Stimulation Therapy”) to Treat Obsessive-Compulsive Disorder. Frontiers in Human Neuroscience. 13:414. https://doi.org/10.3389/fnhum.2019.00414

Wilson, C. (2020) Rubber Hand Illusion and Fake Poo May be the may to Treat OCD. New Scientist. 18 January 2020, pp.17.