Now, Guterstam and his colleagues have tricked humans into actually feeling our peripersonal space.
To do so, they turned to the well-known rubber hand illusion. In the standard form of this illusion, the experimenter uses a paintbrush to stroke a volunteer’s hand (which is hidden from view) and an adjacent, visible rubber hand. The stroking is done simultaneously at the same speed and place on both the real and rubber hand. Within minutes, most people report feeling the touch of the brushstrokes on the rubber hand as if it belonged to them.
In the new study, which involved 101 adults, the researchers made one important change to the experiment. They never brushed the rubber hand directly. Instead, they moved the brush above the rubber hand, again at the same time as brushstrokes that touched the real hand.
This meant the volunteer felt touch on their real hand but watched the brush move in mid-air, say, about 10 centimetres above the rubber hand.
Most volunteers reported feeling a “magnetic force” or “force field” between the paintbrush and the rubber hand below – as if the brush was encountering an invisible barrier.
The first thing that came to mind upon reading this was the phenomenon in aikido where both tori and uke unwittingly collude to an extent that they might both report actually feeling an effect when in fact it’s illusory. Always make sure you maintain some contact with “other” i.e., people not in your in-group.