Neuroscience of free will

The neuroscience of free will is an area within neurophilosophy and is the study of topics related to free will (including volition and the sense of agency), using neuroscience and the analysis of how findings from such studies may impact the free will debate. With the advancement of medical and scientific technology, neuroscientists are now able to study the brains of living humans, allowing them to observe the brain's decision-making processes and revealing insights into human agency, moral responsibility, and consciousness. One of the pioneering studies in this field was conducted by Benjamin Libet and his colleagues in 1983, and has been the foundation of many studies in the years since. Other studies have attempted to predict the actions of participants before they happen, explore how we know we are responsible for voluntary movements as opposed to being moved by an external force, or how the role of consciousness in decision-making may differ depending on the type of decision being made.

Some philosophers, such as Alfred Mele and Daniel Dennett, question the definition of free will used by these researchers. Compatibilists, such as Dennett, argue that free will is compatible with determinism, and that many important and common conceptions of free will are compatible with the emerging evidence from neuroscience. Dennett argued that many neuroscience researchers make a mistake in assuming that the self is separate from the brain. He believed that the type of free will we want is not one that is separate from the neurological processes of our brains, but one that allows us to maintain moral competency and responsiveness to reasons. This preserves the basis of our system for holding each other responsible.

Overview

The neuroscience of free will encompasses two main fields of study: volition and agency. Volition, the power of using one's own will, is difficult to define. If human actions are considered to lie along a spectrum based on conscious involvement in initiating the actions, then reflexes would be on one end, and fully voluntary actions would be on the other. How these actions are initiated and consciousness' role in producing them is a major area of study in volition. Agency is the capacity of an actor to act in a given environment. Within the neuroscience of free will, the sense of agency—the subjective awareness of initiating, executing, and controlling one's volitional actions—is usually what is studied. One significant finding of modern studies is that a person's brain seems to commit to certain decisions before the person becomes aware of having made them. Researchers have found a delay of about half a second or more (discussed in sections below). With contemporary brain scanning technology, scientists in 2008 were able to predict with 60% accuracy whether 12 subjects would press a button with their left or right hand up to 10 seconds before the subject became aware of having made that choice. These and other findings have led some scientists, like Patrick Haggard, to reject some definitions of free will. However, it is very unlikely that a single study could disprove all definitions of free will. Definitions of free will can vary greatly, and each must be considered separately in light of existing empirical evidence. There have also been a number of problems regarding studies of free will. Particularly in earlier studies, research relied on self-reported measures of conscious awareness, but introspective estimates of event timing were found to be biased or inaccurate in some cases. There is no agreed-upon measure of brain activity corresponding to conscious generation of intentions, choices, or decisions, making studying processes related to consciousness difficult. The existing conclusions drawn from measurements are also debatable, as they don't necessarily tell, for example, what a sudden dip in the readings represents. Such a dip might have nothing to do with unconscious decision because many other mental processes are going on while performing the task. Although early studies mainly used electroencephalography, more recent studies have used fMRI, single-neuron recordings, and other measures. Researcher Itzhak Fried says that available studies do at least suggest that consciousness comes in a later stage of decision-making than previously expected – challenging any versions of free will where intention occurs at the beginning of the human decision process.

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