Free Press (2012)
Libet’s famous experiment is introduced at an early stage in this book, and along with similar experiments, it is essentially the whole basis of the author’s argument. In Libet’s studies, activity in the motor cortex was apparent about 300 milliseconds before subjects were conscious of the wish to make a movement. This has since been widely promoted as a proof that free will/consciousness plays no part in determining behaviour.
What is not discussed here is that Libet’s and similar experiments refer only to trivial actions such as moving a finger or wrist, and that the subjects had already agreed to make these small actions at some point in the reasonably near future. Realistically, the outcome of these experiments shouldn’t be a surprise, as everyone has the experience of performing minor actions on auto pilot. Further to this, it is also known that via the dorsal stream in the brain, movements can be performed without the need for conscious vision. What is of greater interest from the point of view of free will is the basis of the deliberated or strategic decisions in life that are seldom discussed in this literature. Notwithstanding this, a whole orthodoxy has been built on the trivial movements of Libet’s experiments.
The author does refer to aspects of the brain vaguely entitled ‘higher’ and ‘lower’ systems, and he also admits that there is a distinction between voluntary and involuntary acts, although it is claimed that voluntary intentions come from ‘nowhere’, meaning generalised unconscious processing in the brain. The problem here is that the ‘from nowhere’ claim doesn’t accord with modern neuroscience.
Neuroscience research over the last two decades shows that conscious images are projected to frontal brain regions, notably the orbitofrontal, the anterior cingulate and other limbic structures, where the reward/punisher values of the sensory inputs are evaluated. These in their turn project to the basal ganglia, which lie upstream of the motor cortex, action and behaviour. This is seen as part of the brain’s limbic or emotional system, and also its reward circuit. We are conscious of these evaluations, and activity in these areas has been shown to be correlated with the subjective appreciation of sensory inputs, rather than the strength of signals from the external environment.
Given the nature of the reward circuit, the author’s argument that choice comes from ‘nowhere’ or in more specific terms that it pops out of the generalised unconscious processing of the brain appears invalid. Rather choice is seen to be the function of restricted areas of the brain, in which neural activities correlated to conscious appreciation or evaluation are seen to be important. In terms of neuroscience, the process of choice is subjective appreciation of the reward value of beer against water, apricots against pears or one piece of chocolate now against two tomorrow, and it correlates to levels of neural activation in the orbitofrontal and other areas. What drives decision taking is the strength of the subjective activation, not the strength of the external signal. One sensory input can create more activity than another in a particular part of the cortex, but in the orbitofrontal this relationship can be reversed with activity becoming correlated to a subjective response rather than the signal strength. The claim that the subjective doesn’t add anything anything to choosing looks hard to substantiate, given the direct correlation between subjective evaluation and neural activity. Evolution selects for adaptive advantage, and it would not have selected for this use of energy by the orbitofrontal, if it was not functional in generating advantageous behaviours.
The author asserts that conscious and unconscious processing are the same, but this does not appear to be valid. Not only does conscious choice arise in restricted areas, but in contrast to these areas, the rest of the brain’s activity can probably be explained in terms of unconscious algorithms. Individual movements can be governed by the non-conscious dorsal visual stream, which requires no reward evaluation, but merely a geometric calculation of positions in space. The conscious visual image arises in the inferior temporal region, but it is value free, and it is only when the image is projected to other areas that it gains subjective value.
Other modern studies also conflict with the Libet orthodoxy. The work of the psychologist, Roy Baumeister, indicates that energy is consumed when subjects exert their conscious will, something that evolution would be unlikely to select for if the conscious will was not functional. Baumeister also showed that in problem solving and academic studies, those students who thought their conscious will could make a difference to their perfromance, actually performed better than those who had been told their scoring was predetermined by a previous test or an IQ rating.
In the twentieth century approach to the brain, the role of emotion was ignored or in fact very nearly taboo in scientific circles. This continues to come through in this book, with an assumption that the brain is about thought processes divorced from emotions, such as those involved in evaluation of inputs. Decisions on actions are described mainly in relation to thinking processes, and ignore the emotional evaluation that modulates them.
It is certainly harder to distinguish between conscious and unconscious here than it is with evaluative processing. However, the model presented in this book, with all thought simply popping out of the unconscious doesn’t stand up well. Executive planning and thought are related most of all to the dorsolateral prefrontal region, and activity in this region is shown to be related to the best established correlate of consciousness, the global gamma synchrony.
Further to this, activity in the dorsolateral is connected to activity in the emotional regions. There is some projection from the orbitofrontal to the dorsolateral. More importantly, the dorsolateral and the orbitofrontal both project to the striatum, which is part of the basal ganglia. In this brain region, specialised neurons are known to combine the inputs of emotional evaluation in the limbic areas and rational planing in the dorsolateral. Even if the workings of the dorsolateral were just pop ups from the unconscious, they would be subject to modulation by areas in which activity correlated to subjective experience is important.Tags: anterior cingulate, conscious will, freewill, Libet, orbitofrontal, Sam Harris Posted by