Fake poop and rubber hands may sound like the punchline of a slapstick comedy joke, but it also may pave the way for treatment in people diagnosed with obsessive-compulsive disorder (OCD), a neurological condition responsible for “immense suffering worldwide.”
The treatment involves a rubber hand and a whole bunch of fake poop. The researchers say that its humorous tendencies may even help to make the therapy a success. It builds on the “rubber hand illusion,” whereby a person places both hands in front of them on a table with a partition in the middle so that they cannot see their real hand but rather – you guessed it – a fake rubber hand. An experimenter will then stroke both the fake and hidden hand for a period of time until the individual begins to report a sense of “feeling” on the fake hand, generally within several minutes.
Researchers placed 29 study participants diagnosed with OCD, an admittedly small sample size, into two groups for a period of hand-stroking. After five minutes, the respondent was asked to rate how much they felt like the hand was their own. The experimenter then took a tissue and rubbed fake poo over the rubber hand while simultaneously dabbing a damp towel on the respondent’s real hand to mimic the feeling. In a second phase, poop was left on the fake hand of participants in the experimental group and wiped clean in the control group while the stroking commenced. A full explanation of the study is available in the journal Frontiers in Human Neuroscience.

By the end of the experiment, those in the experimental group reported feeling less disgusted and anxious while resisting the urge to wash their hands immediately. It is important to note that the experiment did not include people not diagnosed with OCD, a limitation that researchers hope to address in the future.
“Over time, stroking the real and fake hands in synchrony appears to create a stronger and stronger and stronger illusion to the extent that it eventually felt very much like their own hand,” said Baland Jalal, a neuroscientist based in the Department of Psychiatry at the University of Cambridge, in a statement. “This meant that after ten minutes, the reaction to contamination was more extreme. Although this was the point our experiment ended, research has shown that continued exposure leads to a decline in contamination feelings – which is the basis of traditional exposure therapy.”
The rubber hand creates an illusion that the body is being exposed to contamination in a “simple and tolerable” way that eases a patient into therapy, the researchers argue. It even helps a person with OCD “laugh at first” before diving into therapy. By comparison, OCD treatment is normally treated with medications like Prozac or through exposure therapy, such as telling a patient to touch contaminated surfaces, like a toilet, and restrain from washing their hands. For some, this treatment can be stressful and unbearable. An estimated one-in-four patients with OCD will not even begin such therapies because it is too anxiety-inducing.
“OCD can be an extremely debilitating condition for many people, but the treatments are not always straightforward,” explained Jalal. “In fact, exposure therapy can be very stressful and so is not always effective or even feasible for many patients.”
One in 50 people around the world is affected by OCD. Almost half of all patients with OCD exhibit symptoms characterized by severe fears of contamination, which can lead to excessive and irrational behaviors, thoughts, or impulses, according to the World Health Organization. Beyond OCD, an organization dedicated to understanding OCD, notes that the condition can lead to detrimental impacts on personal relationships, well-being, and professional paths.
