Friday, September 10, 2010

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.

6 comments:

Jean-Luc Picard said...

A fascinating insight into the complexities of the human mind These sort of tests can highlight many unexpected results.

SF Girl said...

Yes, Jean-Luc! Very well put!... I am so fascinated by what we are learning about the mind and how it is so much more, always so much more...

Anonymous said...

And thus 3) The mind is easily fooled by illusion.

The V S Ramachandran has created a few illusions the trick the senses. Magicians depend on how easy it is to trick the mind.

Fortunately, V S Ramachandran has leveraged the technique of illusion to help patients to overcome phantom limb pain.

Limburger

SF Girl said...

Ah yes... good point, Limburger...

But who is fooling who? And what is mind, REALLY?

...Who's on first? What's on second?...Is it the chicken or the egg?

...Do we wake from a dreaming sleep or fall asleep from a dreaming wakefullness? Do we make our reality or does reality make us?

Faith... hope... grace... where do these come from? Mind?...

Anonymous said...

Reality, what a concept - Robin Williams.

Mind over Matter

If you don't mind it, it doesn't matter.

Reality is just a state of mind.

Be mindful or never mind.

A mind is a horrible thing to waste, a waist is a horrible thing to mind.

A New York State of mind vs a New York state of mind.

....

el Fromagio

SF Girl said...

HAR! ... Yes, New York was always quite a State... or is that "state"?... :)

And don't get me started on homonyms! They are the boon and the bane of my existence! HAR!