bnevin@CCH.BBN.COM (Bruce E. Nevin) (06/10/88)
Date: Mon, 6 Jun 88 10:38 EDT From: Bruce E. Nevin <bnevin@cch.bbn.com> Subject: brain research on free will To: ailist@ai.ai.mit.edu Here are excerpts from two articles concerning brain research relating to the issue of free will: . . . Benjamin Lebet of the University of California, San Franciso, . . . has been studying EEG correlates of conscious expreience since the early 1960s. He bases his model on his experimental finding that a distinct brainwave pattern, the readiness potential (RP), occurs 350 milliseconds . . . before the subjective experience of wanting to move. . . .There is another interval of 150 milliseconds before actual movement. During that period, the movement--quick flexion of wrist or finger--could be vetoed or blocked by the individual. At the moment they were aware of a conscious decision to act, Libet's subjects noted the position of a moving target. (The accuracy of the notation of time was checked, or corrected, by objective measurements in another setting.) In one experiment, they were asked to note when they actually moved. They reported having moved slightly _before_ any actual fpysiological evidence of movement. It was as if the "mind's muscle"--their image of movement-- preceded actual muscle activation. The brain's motor commands may be experienced as the movement itself. The veto or blockade, Libet commented, is in accord with relitious and humanistic views of ethical behavior and individual responsibility. The choice not to act is "self control." On the other hand, he said, if the final intention to act arises unconsciously, the mere appearance of an intention could not consciously be prevented, even though action could be blocked. Thus religious or philosophical systems can create insurmountable difficulties if they blame individuals for simply having a mental impulse, even if it not acted out. Libet: Physiology Dept., UCSF School of Medicine, San Francisco 94143. This is of course controversial: In a recent issue of _The Behavioral and Brain Sciences_ (8:529-566), 26 well-known researchers from seven countries commented on the implications of Libet's work. . . . Most . . . praised his care and ingenuity and his courage in trying to understand the complex interaction between conscious and unconscious processes. Several doubted that subjective reports of time could ever be precise enough to trust. Others suggested that the experiment is a combination of materialist and mentalist approaches--hard EEG data for the readiness potential and subjective reports for conscious decision. John Eccles of the Max Planck Institute (West Germany) accepted the accuracy of the findings but reinterpreted them in a way that fits his view of mind and brain as separate. Conscious intention, Eccles said, may result from our subconscious sensing of a particular brainwave configuration, the readiness potential. Intention occurs after we sense this subconscious readiness. Subjects may be reporting the peak of an urge, according to James Ringo of the University of Rochester (NY) Medical Center. The very beginning of the "urge waveform" might be the readiness potential evident in the EEG. Conscious will might be triggered by an "anticipatory image," as described in 1890 by William James. Eckart Scheerer of the university of Oldenburg (West Germany) said that Libet's subjects did not report such images preceding the conscious urge because they were not instructed to look for them. The other commentators noted that the will to veto the chosen movement is itself a conscious intention. What precedes it? Charles Wood, a Yale psychologist, noted that an executive function activates a computer's programa. Perhaps the brain's readiness potential is evidence of an executive function that triggers its conscious deciding. I quote both these articles from Brain/Mind Bulletin 11.9:1-2 (May 5, 1986). Bruce Nevin bn@cch.bbn.com <usual_disclaimer>