MedicalResearch.com Interview with:
Veljko Dubljević, Ph.D., D.Phil.
Assistant Professor of Philosophy,
Department of Philosophy and Religious Studies, and
Science Technology and Society Program,
North Carolina State University
Raleigh, NC 27607
MedicalResearch.com: What is the background for this study?
Response: There is considerable controversy about the interpretation of data of the neuroscientific studies done by Benjamin Libet. On the one hand, Libet claimed that his work disproves certain metaphysical conceptions of free will (Libertarianism), whereas it does not disprove others (e.g., Compatibilism). In a nutshell, the reason for these claims is that Libet found preparatory brain activity (Readiness Potentials or RPs) some 500ms before the conscious decision to act was felt by study participants. That seemed to exclude the possibility that mental causation was taking place. At the same time, the onset of movement left a time-window for a ‘veto-decision’. This led Libet to conclude that there is no ‘free will’, but that there is a ‘free won’t’.
On the other hand, there were many criticisms of the study – methodological or substantive. Most notably, Patrick Haggard argued that it is not RPs that are correlates of a decision to act, but Lateralized Readiness Potentials (LRPs). Haggard agreed with many critics of Libet in that RPs could be connected to a range of other phenomena, and that preparatory brain activity that is most important for a decision to act already has to be ‘lateralized’. Namely, the decision to move the left or right arm is critical in this regard, and will lead to RP being focused in one or the other hemisphere, thus making LRPs the point of interest for any conscious decision to act. All in all, Haggard claimed to have replicated Libet’s major findings, with the caveat that timing of LRPs excludes the time-frame for a ‘veto-decision’. This Haggard claimed makes the evidence more in line with the metaphysical doctrine of ‘hard determinism’, which excludes agency and responsibility.
Many other neuroscientists followed Libet’s (and Haggard’s) lead and these experiment became part of ‘lore’ in neuroscience education – many other labs performed similar experiments and claimed to basically replicate the findings.
Our study was the first to review all available evidence.