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Posts Tagged ‘Saul Smilansky’
The history of neuroscientists’ efforts to explore the free will phenomenon was reviewed in 2016 by philosopher and neuroethicist Andrea Lavazza in the journal Frontiers in Human Neuroscience. The setting for our current understanding was drawn a half century ago with the discovery by Hans Kornhuber and Luder Deecke of the Readiness Potential (“RP”), a measurement of increased bio-electric activity in the brain. The RP was measured by an electroencephalogram (“EEG”), a procedure in which electrodes were placed on a subject’s scalp to allow for the recording of bio-electric activity. This activity was seen as an indication of preparation for a volitional act.
One question raised by the discovery of RP was whether an individual was conscious of an intention to act before RP appeared. In the early 1980s, Benjamin Libet, a son of Jewish immigrants from Ukraine who became a neuroscientist at the University of California-Davis, sought to answer that question. Libet and his team designed a relatively simple test. First, subjects were wired for an EEG. To record muscle contraction, electrodes were also placed on subjects’ fingers. Then the subjects were asked to do two things, spontaneously move their right finger or wrist, and, with the aid of a clock in front of them, report to researchers the time they thought they decided to do so.
What Libet found (Libet et al. 1983) was that conscious awareness of the decision to move a finger preceded the actual movement of the finger by 200 milliseconds (ms), but also that RP was evident 350 ms before such consciousness. While Libet recognized that his observations had “profound implications for the nature of free will, for individual responsibility and guilt,” his report appropriately contained several caveats. First, it noted (at 640) that the “present evidence for the unconscious initiation of a voluntary act of course applies to one very limited form of such acts.” Second (at 641), it allowed for the possibility that there could be a “conscious ‘veto’ that aborts the performance . . . (of) the self-initiated act under study here.” Finally (at 641), it acknowledged that “the possibilities for conscious initiation and control” in situations that were not spontaneous or quickly performed. read more