Out of body rabbit experience (Image: William Koechling/Getty)

In a new twist on an old illusion, people have been made to feel an “imaginary rabbit” hopping along a stick resting between their fingers.

The trick is a variation on a tactile illusion called the cutaneous rabbit in which a series of discrete taps to two areas of skin are perceived as movement between those two areas. For instance, two taps to the elbow followed by a single tap to the wrist will feel as if a “rabbit” is hopping towards the wrist.

Makoto Miyazaki, a cognitive neuroscientist at Kochi University of Technology in Japan, was using this decades-old trick to test perception when he realised that the effect seemed to jump from his body onto the object he was holding at the time.


To investigate further, Miyazaki used an electrically operated device to administer taps to eight volunteers while they held a 10-centimetre aluminium rod between two fingers. The volunteers were then asked to describe where they felt the taps.

Finger tapping

The device delivered two taps to the first finger, 800 milliseconds apart, then tapped the second finger 50 or 80 milliseconds later.

As with the classical version of the illusion, volunteers did not sense discrete taps to one finger and then the other. Instead, they felt the taps move up or down the stick, depending on the order in which they were delivered.

The participants sensed the first tap as being on their finger, the second tap (which was actually on the same finger) as being halfway down the rod, and the third tap on the second finger, which is where it actually was.

In control experiments, volunteers not holding the rod who were given the same sequence of taps reported no sensation passing between their fingers.

“It is a bit astonishing,” says Felix Blankenburg, a neuroscientist at the Bernstein Center for Computational Neuroscience in Berlin, Germany, who in a separate experiment scanned the brains of people experiencing the cutaneous rabbit illusion.

Body map

Blankenburg’s study pinpointed activity in a part of the brain called the somatosensory cortex, an area that maintains an internal body map.

“According to common-sense physiology, this stick should not be included in the body map,” Miyazaki says. To feel the “rabbit” hop onto the stick, so to speak, could mean that the body map is more changeable than previously thought, he says.

He plans to run experiments which scan brain activity during the illusion, in the hope that this will pinpoint the exact mechanisms responsible.

Journal reference: The Journal of Neuroscience, DOI: 10.1523/jneurosci.3887-09-2010

Read more: explore more tactile illusions in our special feature