A 2008 study entitled 'Unconscious determinants of free decisions in the human brain' has added weight to what some may deem 'unbelievable' findings by previous studies, which suggest (yes, you read the title correctly) that our decisions have, in fact, been predetermined before we are even conscious of making one. A group of researchers with affiliations to the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig Germany and the Bernstein Centre for Computational Neuroscience in Berlin set about confirming these findings by addressing some open questions that were apparent within previous published work in the area. One of the most notable studies in this area is that of Benjamin Libet's 1985 study where participants were instructed to press a button as soon as they felt the urge to do so, during which time their electrical brain activity was recorded. This study revealed that the participants' conscious decision to press the button was preceded by a few hundred milliseconds by a negative brain potential (the so-called ‘readiness potential’) that originates from the supplementary motor area (SMA) which is a brain region that is associated with motor preparation. Due to the findings that the recorded brain activity in the SMA routinely preceded participants' conscious decisions, it has been proposed that the brain had unconsciously made the decision to move even before the participant was aware of it.
Fascinating as findings of this nature are, Soon et al., (2008) pointed to some issues that needed addressing. (1) “the readiness potential is generated by the SMA, and hence only provides information about late stages of motor planning” – Therefore it is not clear if the SMA is the precise cortical area responsible for where the decision for movement stems from or if other high level planning stages are involved. (2) “the time delay between the onset of the readiness potential and the decision is only a few hundred milliseconds” – The researchers acknowledge the arguments that suggest that there may be inaccuracies in the measurement of the decision time at short delays which can lead to distorted judgements of the timing of brain activity and intention. (3) “does any leading brain activity indeed selectively predict the specific outcome of a choice ahead of time?”. To rule out the possibility that a leading brain activity does not just convey ‘unspecific preparatory activation’ the researchers acknowledge the necessity of looking at free decisions in terms of multiple behavioural options.
These previously disputed issues were adequately addressed in this 2008 study and one could argue that this is what really brings home the implications of such reconfirmed findings. In this study the researchers instructed consenting participants to carry out a freely paced motor-decision task while their brain activity was measured using functional magnetic resonance imaging (fMRI). Participants were instructed to fixate on the centre of a screen where a series of letters were shown to them. Participants were to freely decide between one of two buttons to be pushed ‘immediately’ by the right and left index fingers at a time when they felt the urge to do so. In investigating whether any brain regions encoded the participants’ motor decision ahead of time, it was found that “two brain regions encoded with high accuracy whether the subject was about to choose the left or right response prior to the conscious decision”. The researchers of this study claim to go beyond that of other studies by indicating that “the earliest predictive information is encoded in specific regions of frontopolar and parietal cortex, and not in SMA”. For anyone even slightly interested in the workings of and theories associated with the human mind, results like these are sure to fascinate! Here is a video showing an example of one of Libet’s experiments.
Obviously findings of this nature are sure to draw both disbelief and expected criticism. The idea that one’s decision making process is largely an unconscious activity has clear consequences for our ideas about free will etc. I agree that even the thought of free will as being one big illusion or our consciousness as being just a mere biochemical afterthought is shocking, almost frightening! Of course there are many disbelievers, especially some philosophers who feel these results are misguiding. For a more detailed discussion of Soon et al., (2008) and Libet’s findings and what are potential philosophical counterarguments to such findings, click here for a nicely written blog style piece by Kerri Smith. Click here for more on Benjamin Libet and free will.