The Power of the Mind and the Phantom Hand

Such stuff as dreams are made on—William Shakespeare

Vilayanur S. Ramachandran and Diane Rogers-Ramachandran at the Center for Brain and Cognition at the University of California in San Diego conducted an incredibly illuminating experiment on mind and perception (reported in the Premiere issue of Scientific American Mind, Feb 2005).

Briefly, the experiment involved a subject whose right hand was concealed from her while a fake plastic right hand was placed in full view. The experimenter repeatedly tapped or stroked the person’s concealed hand, while simultaneously doing the same to the plastic hand. After half a minute the person whose concealed hand was being stroked began to feel the fake hand being stroked! “The sensations seem to emerge directly from the plastic rather than from [the person’s] actual hidden flesh,” reported Ramachandran and Rogers-Ramachandran. This illusion was first reported by Matthew Botvinick and Jonothan Cohen at the University of Pittsburgh in 1998; they suggested that look and proximity of the fake hand to the hidden real hand was enough to fool the brain.

But there’s more.

Ramachandran and other researchers revealed that the object being stroked did not need to resemble a hand to produce the effect; the same effect could be elicited by stroking the table. When the same experiment was conducted without the fake hand—stroking the table—the subject eventually felt touch sensations emerging from the wood surface in front of them.

It gets even better…

Kathleen Carrie Armel and Vilayanur Ramachandran demonstrated perceptual assimilation: when the table or dummy hand was “threatened” the person winced and even started sweating. According to Ramachandran and Rogers-Ramachandran, two important principles of perception are demonstrated by this:

1. Perceptions is largely based on extracting statistical correlations from sensory inputs. The brain weighs the likelihood of two random phenomena are identical by chance and makes a deduction;

2. The mental mechanisms that extract the correlations are based on the autonomic processes, which are relatively unsusceptible to higher-level intellect. The brain makes its judgments automatically from the sensory input without involving conscious cognition.

“One premise that seems to be beyond question is that you are anchored in your body,” the authors say. Ah…. “there are more things in heaven and earth, Horatio, Then are dreamt of in your philosophy” to end with our friend Wil again. One could easily apply this to the mind, certainly its own universe.

Nina Munteanu is an ecologist and internationally published author of novels, short stories and essays. She coaches writers and teaches writing at George Brown College and the University of Toronto. For more about Nina’s coaching & workshops visit www.ninamunteanu.me. Visit www.ninamunteanu.ca for more about her writing.