Robot used in perception tests

A newly designed robot creates the illusion of a “presence” in the room, but it wasn’t created for a big-budget haunted house. This device is a tool for neurological research and could help scientists better understand conditions such as schizophrenia.

The robot and its related experiments are described in a paper published recently in Current Biology. The researchers started with a hypothesis about what causes people to sense someone who isn’t there. In 12 patients who suffered from these hallucinations because of conditions including epilepsy, strokes, migraines and brain tumors, the researchers found that regions of the brain dealing with self-perception were usually damaged.

“We also found that the hallucinated presence was usually in the same position as the subject. If the patient was standing, so was the sensed presence, and the same if the patient was sitting,” said lead author Giulio Rognini, a post-doctoral researcher at the Swiss Federal Institute of Technology in Lausanne. “So we felt that the feeling of a presence was being caused by a misperception of ones own bodily signals.”

Rognini and his collaborators, who included Olaf Blanke — known for his experiments in inducing out-of-body experiences — set about to create this same mind-body confusion in healthy patients.

While blindfolded, subjects inserted their finger into a mechanism on the robot and moved it. This prompted the robot to mimic the motion with a pointer pressed against the subject’s back. When the movement of their finger was synced to the robot’s, they didn’t report any unusual sensations. But when the robot’s movement was out of sync with the controller — the robot prodder’s movements, while driven by the study subject’s own finger, happened slightly later — things got creepy.

After these out-of-sync tests, subjects reported feeling like someone was standing behind them. Many of them began drifting backward towards the presence they felt. Two of them were so uneasy in the experiment that they asked if they could stop.

When asked to list how many people had been nearby, the subjects who’d been paired with an out-of-sync robot counted extra people — one more, on average — than those who’s movement was synced with the robot.

Rognini and Blanke say they hope the test results will be enlightening. The researchers say that a haywire sense of self may be part of some neurological disorders and hope that further research will help reveal the mechanisms of these diseases.