Friday, June 5, 2015

The Evidence From Neuroscience That Free Will Is An Illusion

Starting with Benjamin Libet's experiments in 1983 which gave some of the earliest evidence that conscious decisions are preceded by unconscious neural activity, there have been numerous scientific studies recently that have confirmed this to a much higher degree. Here is a list of some of those tests:

Unconscious determinants of free decisions in the human brain


  • Taken together, two specific regions in the frontal and parietal cortex of the human brain had considerable information that predicted the outcome of a motor decision the subject had not yet consciously made. This suggests that when the subject’s decision reached awareness it had been influenced by unconscious brain activity for up to 10 seconds.
  • The temporal ordering of information suggests a tentative causal model of information flow, where the earliest unconscious precursors of the motor decision originated in frontopolar cortex, from where they influenced the buildup of decision-related information in the precuneus and later in SMA, where it remained unconscious for up to a few seconds.

Tracking the Unconscious Generation of Free Decisions Using UItra-High Field fMRI


  • Researchers show that it was possible to decode the decision outcomes of such free motor decisions from the pole of anterior medial prefrontal cortex (BA 10) and the precuneus/posterior cingulate cortex (PCC), up to 7 s before subjects were aware of their intention.
  • Taking into account the temporal delay of the BOLD signal (which is in the order of a few seconds), it is possible that these signals reflect processes up to 10 seconds before the actual decision.

Predicting free choices for abstract intentions


  • Researchers are able to show that the outcome of a free decision to either add or subtract numbers can already be decoded from neural activity in medial prefrontal and parietal cortex 4 s before the participant reports they are consciously making their choice.
  • Previous findings have been mostly restricted to simple motor choices.
  • In the current study, participants were not cued to make decisions at specific points in time but were allowed to make decisions spontaneously. By asking participants to report when they first consciously decided, we could investigate what happened in the brain before the decisions were consciously made. We found that both medial frontopolar cortex and posterior cingulate/precuneus started to encode the specific outcome of the abstract decisions even before they entered conscious awareness. Our results suggest that, in addition to the representation of conscious abstract decisions, the medial frontopolar cortex was also involved in the unconscious preparation of abstract decisions.

Reading My Mind


  • CBS 60 minutes report from 2009 showing how fMRI imaging can recognize with a high degree of accuracy the contents of thoughts about objects like a hammer, a window, an apartment etc. 
  • Report reveals there are enough similarities between different people such that once enough people's brains are measured when thinking about an object, a person who never scanned can have their thoughts predicted with 100 percent accuracy when thinking about those objects. 

Internally generated preactivation of single neurons in human medial frontal cortex predicts volition.


  • Recording the activity of 1019 neurons while twelve subjects performed self-initiated finger movement, this study shows progressive neuronal recruitment over ∼1500 ms before subjects report making the decision to move.
  • A population of 256 SMA (supplementary motor area) neurons is sufficient to predict in single trials the impending decision to move with accuracy greater than 80% already 700 ms prior to subjects' awareness. Furthermore, they predict, with a precision of a few hundred ms, the actual time point of this voluntary decision to move.
  • Using an SVM classifier to predict the time point at which the subject reported making the decision to move, the algorithm detected the occurrence of the decision in 98% of the trials and only missed W in 2% of the trials.

There Is No Free Won’t: Antecedent Brain Activity Predicts Decisions to Inhibit


  • Our main argument is as follows: Libet et al, (1983) had suggested that decisions to inhibit action have an important role in freedom of will, because, he argued, they do not have any obvious unconscious neural precursors. In Libet’s view, this makes decisions to inhibit crucially different from decisions to act, for which, he claimed, there is a clear unconscious precursor. Libet’s dualistic notion of “free won’t” has been criticised on theoretical grounds. However, in our view, a stronger rejection of “free won’t” could come from actually showing that a decision to act or not can be driven by a preceding, presumably unconscious neural activity. Our results identify, for the first time, a candidate unconscious precursor of the decision to inhibit action. These results count as evidence against Libet’s view that the decision to inhibit action may involve a form of uncaused conscious causation.
  • The dualistic view that decisions to inhibit reflect a special “conscious veto” or “free won’t” mechanism is scientifically unwarranted.

As the data keeps piling up the evidence against free will gets stronger and stronger. If mental phenomena were caused by electro-chemical brain states as the data shows, the traditional dualistic picture of mind causing physical states is empirically ruled out by the data. Libertarian free will, and dualistic interactionism have no empirical support. The question now is whether you're a compatibilist or an incompatibilist. This is not to say that this evidence alone is absolute proof free will is an illusion, or that we've resolved the hard problem of consciousness. We still don't know how the brain causes consciousness, and it is possible we may never. But, we don't need to know how the brain causes consciousness in order to know that the brain causes consciousness. 

*This list will grow as I find more studies.

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