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Free Will: Libet And The Readiness Potential
Then, in the 1980s, the physiologist Benjamin Libet conducted a set of experiments which appeared to finally settle the matter. Libet asked volunteers to flick one of their fingers or wrists, measuring their brain activity through electrodes whilst they did so. The volunteers were also instructed to watch a clock, and report to Libet when they had made the decision to move. Libet found that the volunteers’ decision to move was preceded by a characteristic brainwave pattern known as a “readiness potential”, which was interpreted as the brain preparing for movement. This readiness potential appeared around half a second before the participants claimed they had made the decision to move. Libet interpreted this to mean that all of our choices are made unconsciously without us being aware of them. We merely rationalise them after the event, creating the illusion of free will. A variant of Libet’s experiment was performed by a group of researchers in 2008. This time, participants were asked to choose whether to raise their left or right hands. The researchers found that they were able to accurately predict the volunteers’ choices up to 10 seconds before the volunteers themselves were aware of them. Criticisms This would appear to be the final nail in the coffin for free will. If you can predict my choices ten seconds before I feel like I make them, how can I genuinely be making those choices at all? However, this interpretation leaves several questions unanswered. Firstly, why would the illusion of free will ever evolve? If my unconscious mind is capable of making complex decisions, why is there the need for consciousness at all? Many people think of the ego/central executive/conscious part of themselves as being like a driver in a vehicle, and I suggest that this is why they have trouble reconciling Libet’s findings with their conceptions of free will. The ego is more like the captain of a ship, engaged in commanding a crew – directing, modifying, approving and vetoing decisions which are formulated unconsciously but presented to consciousness for review before they are executed. This is in keeping with evolutionary psychology. The psychologist and neuroscientist Merlin Donald has theorised that the speciation of Homo erectus introduced a new cognitive system, based around the ability to consciously recall, review and modify episodic memories in order to create representations of intended behaviour, or action models; an ability he terms “mimesis”. The Mimetic System and the Ego Although apes possess a high capacity for episodic memory, they are unable to recall those memories without an environmental cue, and so cannot reflect on past experiences. Without the ability to construct action models and voluntarily recall them, the mind remains purely reactive. It is impossible to rehearse or refine any skill; an ability which is fundamental to making and using tools. The mimetic system thus developed as humans learnt to make and use tools. In turn, Donald theorises that the linguistic system is a highly specialised mimetic subsystem. Conscious thought, in the form of internal dialogue, is a consequence of the linguistic system’s ability to create, rehearse and review phonological action models without executing them. Words are thus highly specialised episodic memories. The mimetic system’s ability to consciously retrieve memories and review action models necessitates a central executive; i.e., there must be some unitary awareness to perform the actual reviewing. In functional terms, all that would be necessary to create such a unitary awareness would be an internal loop whereby motor commands, instead of being instantly executed, were first sent to a particular subfield of consciousness which evaluated them based on either emotive or cognitive processing. Once the linguistic system evolved, this central executive also took on the role of reviewing and executing phonological action models. Since conscious thought is merely linguistic action modelling, the ego thus became associated with conscious thought, or internal dialogue. Merlin Donald’s theories provide a detailed account of (1) how the ego evolved, (2) what its functions are, and (3) the role it plays in consciousness. Fundamentally, this account provides an explanation as to how our conscious decision making ability evolved, and supports the assertion that the ego is engaged in directing, modifying, approving and vetoing decisions which are formulated unconsciously but presented to consciousness for review before they are executed. Within this framework, Libet’s “readiness potential” might plausibly correspond to the construction of an action plan. However, there are other reasons to reject the idea that Libet’s findings invalidate free will. Deterministic Free Will Determinism holds that if all events are determined by their causes, then everything that occurs – including all human behaviour – is inevitably set by the past, and there can therefore be no such thing as free will. An event which is, hypothetically, not determined by its causes is referred to as random. Random processes, meanwhile, are referred to as stochastic processes. It is possible that the universe may contain both random and deterministic events – however, it is not necessary to debate whether or not randomness exists in order to ask whether randomness is necessary in order for free will to exist. We have to ask, would a choice made without prior cause be a free choice? I define free will (or volition) as a capacity for conscious, purposeful decision making. When I make a choice, I evaluate the available options with regards to my emotions, beliefs, values, etc., and then choose the option most consistent with my own best interests, or which best fits my own purposes at any given time. Could I call this decision making process “free” if I chose an available option at random – through some psychological process equivalent to rolling a dice, for example? If such a process was volitional, “free will” would be identical with “random action”, and this is not the case – random action is in fact the exact opposite of free will. If my actions were in no way dependent on my thought processes, emotions, values, etc., then I could not be said to have free will – I would be trapped within a body over which I had absolutely no control. It is clear that calling an action free does not mean that that action is free from causality. My choices are dependent on reasons, since the human mind itself is a deterministic system, and these reasons determine which course of action I decide on. My actions are determined by my own psychological processes: my lines of reasoning, my desires and emotional reactions, my own deliberation. In fact, it is because psychological processes are deterministic that we are able to freely make choices at all. Rebutting Libet It should be noted that there are random processes in the brain. In the 1980s, researchers in chaos theory attempted to create computer models of the brain based on deterministic chaos, but these did not approximate real human brain activity. However, in the 1990s, researchers found that the brain generates random noise. When programmers incorporated a random element into their computer simulations, they found that it created models which matched the pattern of the brain’s activity. The existence of randomness in the brain leaves open the possibility that we sometimes make decisions randomly, through the psychological equivalent of flipping a coin. However, as outlined above, this would be the opposite of free will. This leads us back to Benjamin Libet. Crucially, Libet’s experiment involves a random choice – the opposite of free will. Deciding which hand to raise, or what time to raise it, is the mental equivalent of flipping a coin. There is no conscious deliberation – no logic, emotion, instinct, etc. Randomness is built into the set-up, precluding free will by the terms of the experiment. There can be no doubt that humans often operate on autopilot – maybe even most of the time. But that doesn’t mean we don’t have the capacity to exercise free will through deliberation: by evaluating our options and making considered choices. Libet’s experiment and the conclusions that are often drawn from it reflect a bias towards randomness (and against free will) which is built into the experiment itself. Article Directory: http://www.articledashboard.com Copyright (C) Dan Haycock 2011. For similar articles and information about Dan's forthcoming book, visit www.DanHaycock.co.uk |
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