The Libet Experiments
Trevor Mendham01-Aug-2013: Original version
The Libet experiments took place in the 1980s. Many people have taken them to represent the death of
free will.
The experiments are described in detail in Libet 1983. A brief summary is that subjects were asked to watch a rotating dot and, at a time
of their choosing, make a hand movement. The subject's report of the position of the dot was used to note the time the decision was made. Similarly, electrodes were used to measure the activity of the brain. The experiments showed that brain activity ("readiness potential" or "RP")
occurred before the subject believed that a choice had been made.
The implication drawn by many people is that the subject did not consciously decide when to act. The apparent conscious decision had
already been made subconsciously as a result of physical processes in the brain. The apparent free will of the subject was simply a self-
delusionary afterthought.
Others have analysed Libet's methodology in detail and raised questions about the timing mechanism. There has also been more recent
research (Trevena and Miller 2010) that casts doubt on the link between RP and a positive decision to act.
The act of free will was deciding to take part in the experiment. Once that decision had been made, the details of
watching the dot and making the movement could be left to largely automatic processes. The low level decision to move the hand was
indeed made automatically. However the subject could at any time have expressed free will by getting up or making a decision not
to make a movement at all.
It should be noted that Libet tried to encourage "spontaneous" action. The wording given to many of the subjects includes:
So the results of the Libet experiment are consistent with the Presidential metaphor. Free will is exercised by the President
making the decision to take
part in the experiment then delegating the actual work to the relevant department. The delay between RP and conscious awareness
represents the delay in the department reporting back to the President.
Defending Free Will
Not everybody interprets the Libet experiments as meaning that free will does not exist. Libet himself noted that his subjects sometimes
"vetoed" an apparent desire to act; readiness potential built up but no action occurred. Libet referred to this veto as being a
free won't.My Position
My position is that even if RP correlates with the beginning of an action, this is not necessarily a conflict with the idea of
free will."to let the urge to act appear on its own at any time without any preplanning or concentration on when to act"
This wording is consistent with a response that delegates the actual low level decision making to a semi-autonomous process.
(Libet 1983).
References:
Libet, Benjamin et al. 1983. Time of Consciousness Intention to Act in Relation to Onset of Cerebral Activity (Readiness-Potential). Brain vol 106
Trevena, Judy and Miller, Jeff. 2010. Brain preparation before a voluntary action: Evidence against unconscious movement initiation. Consciousness and Cognition, Vol 19 Issue 1.
