page_title: Neuroscience of free will
section_title: Analysis and interpretation
hierarchical_section_title: Neuroscience of free will / Notable experiments / Unconscious actions / Timing intentions compared to actions / Analysis and interpretation
caption_attribution_description: Čeština: Atletky zakleknuté ve startovních blocích těsně před startem běhu na 200 m žen při 17. ročníku Memoriálu Josefa Odložila (Premium mítink EAA, stadion Na Julisce, Praha-Dejvice, 14. června 2010). (270) Lenka Kršáková (SVK) (272) Lucie Škrobáková (CZE) (168) Isabel Le Roux (RSA) (169) Carol Rodríguez (PUR) (171) Denisa Rosolová (CZE) English: Athletes in starting blocks seconds before start of women's 200 m run at 17th edition of the Josef Odložil Memorial (EAA Premium Meeting, Na Julisce Stadium, Prague, Czech Republic, 14 June 2010). (270) Lenka Kršáková (SVK) (272) Lucie Škrobáková (CZE) (168) Isabel Le Roux (RSA) (169) Carol Rodríguez (PUR) (171) Denisa Rosolová (CZE)
context_page_description: Neuroscience of free will, a part of neurophilosophy, is the study of topics related to free will using neuroscience, and the analysis of how findings from such studies may impact the free will debate.
  As it has become possible to study the living human brain, researchers have begun to watch decision-making processes at work. Studies have revealed unexpected things about human agency, moral responsibility, and consciousness in general. One of the pioneering studies in this domain was conducted by Benjamin Libet and colleagues in 1983 and has been the foundation of many studies in the years since. Other studies have attempted to predict participant actions before they make them, 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.
  The field remains highly controversial. The significance of findings, their meaning, and what conclusions may be drawn from them is a matter of intense debate. The precise role of consciousness in decision making and how that role may differ across types of decisions remains unclear.
context_section_description: This study is similar to Libet's in some ways: volunteers were again asked to perform finger extensions in short, self-paced intervals. In this version of the experiment, researchers introduced randomly timed "stop tones" during the self-paced movements. If participants were not conscious of any intention to move, they simply ignored the tone. On the other hand, if they were aware of their intention to move at the time of the tone, they had to try to veto the action, then relax for a bit before continuing self-paced movements. This experimental design allowed Matsuhashi and Hallet to see when, once the subject moved his finger, any tones occurred. The goal was to identify their own equivalent of Libet's W, their own estimation of the timing of the conscious intention to move, which they would call "T" (time).
  Testing the hypothesis that "conscious intention occurs after movement genesis has already begun" required the researchers to analyse the distribution of responses to tones before actions. The idea is that, after time T, tones will lead to vetoing and thus a reduced representation in the data. There would also be a point of no return P where a tone was too close to the movement onset for the movement to be vetoed. In other words, the researchers were expecting to see the following on the graph: many unsuppressed responses to tones while the subjects are not yet aware of their movement genesis, followed by a drop in the number of unsuppressed responses to tones during a certain period of time during which the subjects are conscious of their intentions and are stopping any movements, and finally a brief increase again in unsuppressed responses to tones when the subjects do not have the time to process the tone and prevent an action – they have passed the action's "point of no return". That is exactly what the researchers found (see the graph on the right, below).
  The graph shows the times at which unsuppressed responses to tones occurred when the volunteer moved. He showed many unsuppressed responses to tones (called "tone events" on the graph) on average up until 1.8 seconds before movement onset, but a significant decrease in tone events immediately after that time. Presumably this is because the subject usually became aware of his intention to move at about −1.8 seconds, which is then labelled point T. Since most actions are vetoed if a tone occurs after point T, there are very few tone events represented during that range. Finally, there is a sudden increase in the number of tone events at 0.1 seconds, meaning that this subject has passed point P. Matsuhashi and Hallet were thus able to establish an average time T (−1.8 seconds) without subjective report. This, they compared to ERP measurements of movement, which had detected movement beginning at about −2.8 seconds on average for this participant. Since T, like Libet's original W, was often found after movement genesis had already begun, the authors concluded that the generation of awareness occurred afterwards or in parallel to action, but most importantly, that it was probably not the cause of the movement.
caption: A simple "signalling noise" is used, but it is to warn participants that they must prevent any actions they are aware of.
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