Finding a way to do this is probably why the experiment became so famous.
#Mind over matter origin free
He was trying to measure something purely mental - the free decision, or thought, of wanting to act. This really is tricky because there is, by definition, no physical activity in the brain or anywhere else that corresponds to this. He then measured three things - the time at which the movement began, the time at which the " readiness potential" in the brain began (signalling the brain starting to organise the coming movement) and then, most tricky of all, the time at which the subject made the decision to move. He asked subjects in the laboratory to hold out their arm and, whenever they felt like it and of their own free will, to flex their wrist. Unlike all the thousands of people who have argued around this point, Libet actually found a way to test it. Yet philosophers and scientists for hundreds of years have argued that the brain does not need a magical conscious self to start actions off, and free will must be an illusion. Certainly we feel as though we consciously decide to act and then do so. In this experiment he wanted to find the cause of our spontaneous, deliberate actions.
This may be weird enough, but it is for his experiment on free will that he will mostly be remembered. This is the origin of what is often called "Libet's half-second delay". Instead, he proposed (and provided plenty of evidence for) the idea that sensations are subjectively antedated to the time of the initial brain effect, but are only consciously experienced if half a second of activity follows. It is not true to say that you need half a second of stimulation and then the sensation is felt that would mean our experience of the world would be delayed by half a second and we'd all be dead.
#Mind over matter origin series
First there was a series of studies of the timing of neural events, showing that when you directly stimulate the brain with tiny pulses of electricity it requires about half a second of continuous stimulation of the sensory cortex for a conscious sensation to be felt. He had, in fact, carried out lots of experiments on consciousness since the early 1970s. After a conference in Berkeley he invited me for lunch in a little Chinese restaurant and then we walked around Golden Gate Park, talking nineteen to the dozen about consciousness, mind, life, free will and the meaning of death.Īnd of course we talked about his famous experiment. So I must be content with my happy memories of the one time we did meet, back in 1991.
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