"We primates are highly visual creatures," he said.
In a situation like the rubber hand illusion, the brain struggles to make sense of conflicting inputs from senses of sight and of feel.
Ramachandran noted that in other tests of the rubber hand illusion, subjects would often show a physiological response if something painful were done to the phantom hand.
Conversely, when something cold was applied to the real hand, the person would often have a more minimal reaction, because they had disowned it.
Ultimately, they hope this research will lead to treatments for a number of mental ailments.
Self-perception problems have been implicated in a host of disorders, which include phantom pain and schizophrenia, and also self-image problems like anorexia.
One way this principle has been used is to treat phantom pain. Ramachandran said that by using a mirror, a subject can be "tricked" into thinking that a phantom limb has been resurrected.
The mirror is placed in the center of the body, and by moving the existing limb, subjects will come to believe that they are in control of the one they have lost.
"It is again telling you that in neurology you are not talking about fixed connections," Ramachandran said. "You can press the reset button."
As for our self-image, Ramachandran notes that "it is constantly being modified due to changing senses of inputs. … When you do these experiments, you're surprised by how malleable it is."