Brain preparation before a voluntary action: Evidence against unconscious movement initiation. Consciousness and Cognition, 19, 447-56

Dunedin School of Medicine, University of Otago, New Zealand
Consciousness and Cognition (Impact Factor: 2.31). 03/2010; 19(1):447-456. DOI: 10.1016/j.concog.2009.08.006


Benjamin Libet has argued that electrophysiological signs of cortical movement preparation are present before people report having made a conscious decision to move, and that these signs constitute evidence that voluntary movements are initiated unconsciously. This controversial conclusion depends critically on the assumption that the electrophysiological signs recorded by Libet, Gleason, Wright, and Pearl (1983) are associated only with preparation for movement. We tested that assumption by comparing the electrophysiological signs before a decision to move with signs present before a decision not to move. There was no evidence of stronger electrophysiological signs before a decision to move than before a decision not to move, so these signs clearly are not specific to movement preparation. We conclude that Libet’s results do not provide evidence that voluntary movements are initiated unconsciously.

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    • "47 Moreover, recent studies (King, 2014; Pockett, 2006; Schlegel et al., 2013; Schurger, 48 Sitt, & Dehaene, 2012; Trevena & Miller, 2010) are not consistent with (Libet et al., 1983) 49 and hence their claims are controversial (King, 2014; Libet, 2006; Pockett, 2006; Schlegel 1 et al., 2013; Schurger et al., 2012; Trevena & Miller, 2010). The eDAM framework can 2 address this controversy; for example, the readiness potential may be the 3pp-physical 3 aspect of the mind-brain-state, and its 1pp-mental aspect indicates that the subject is 4 merely paying attention (King, 2014; Trevena & Miller, 2010). 5 The eDAM framework is consistent, to a certain extent, with other dual-aspect views 6 such as (a) reflexive monism (Velmans, 2008), (b) triple-aspect monism (physical, non- 7 conscious mental, and conscious mental aspects) (Pereira Jr., 2013) and (c) retinoid 8 framework (Trehub, 2013), but each have its own problems as elaborated above and in 9 Section 2.3. "
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    DESCRIPTION: Previously, an extended version of dual-aspect monism (eDAM) framework for consciousness was proposed: It (a) has the least number of problems, (b) addressed the ‘hard’ problem of consciousness (how to explain subjective experiences), and (c) can be tested scientifically. Here, the term ‘consciousness’ is defined as the mental aspect of a state of brain-system or that of a state of brain-process from the first person perspective; consciousness has two sub-aspects: conscious experience and conscious function. The terms ‘mental’ and ‘physical’ are used in the sense of the eDAM framework (not dualism). The eDAM framework has five components: dual-aspect monism, dual-mode, varying degrees of manifestation of aspects depending on the levels of entities and contexts, necessary conditions of consciousness, and the segregation and integration of dual-aspect information. In Searle’s Biological Naturalism (BN), conscious states are real and irreducible, caused by lower level brain processes, realized as higher-level or system features, and function causally. Here, the eDAM framework attempts to: (a) interpret BN and address the objections raised in BN by traditional views (dualism and materialism), (b) investigate if conscious robots can be supported, and (c) investigate if the eDAM is parsimonious and more efficient compared to other frameworks.
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    • "subjects ∼200 ms before the onset of the actual movement , and up to ∼2 s after the onset of movement - related brain potentials , such as the readiness potential ( Shibasaki and Hallett , 2006 ) . Although both the validity of the W - moment as a reliable measure of the timing of the intention and the interpretation of the readiness potential as reflecting motor preparation have been criticized ( Gomes , 1998 ; Trevena and Miller , 2010 ; Schurger et al . , 2012 ) , following studies have replicated the main finding ( Haggard and Eimer , 1999 ; Soon et al . "
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    ABSTRACT: The temporal relationship between our conscious intentions to act and the action itself has been widely investigated. Previous research consistently shows that the motor intention enters awareness a few hundred milliseconds before movement onset. As research in other domains has shown that most behavior is affected by the emotional state people are in, it is remarkable that the role of emotional states on intention awareness has never been investigated. Here we tested the hypothesis that positive and negative affects have opposite effects on the temporal relationship between the conscious intention to act and the action itself. A mood induction procedure that combined guided imagery and music listening was employed to induce positive, negative, or neutral affective states. After each mood induction session, participants were asked to execute voluntary self-paced movements and to report when they formed the intention to act. Exposure to pleasant material, as compared to exposure to unpleasant material, enhanced positive affect and dampened negative affect. Importantly, in the positive affect condition participants reported their intention to act earlier in time with respect to action onset, as compared to when they were in the negative or in the neutral affect conditions. Conversely the reported time of the intention to act when participants experienced negative affect did not differ significantly from the neutral condition. These findings suggest that the temporal relationship between the conscious intention to act and the action itself is malleable to changes in affective states and may indicate that positive affect enhances intentional awareness.
    Frontiers in Psychology 08/2015; 6(1307). DOI:10.3389/fpsyg.2015.01307 · 2.80 Impact Factor
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    • "We assumed that the brain activity specific for hypnosis would be reflected as an observable increase in the excitability of M1. No facilitatory effect on corticospinal excitability was found in the TS condition, despite the fact that conscious motor intention emerges as a result of neural computations carried out within a parietal-motor network (Desmurget and Sirigu, 2009; Trevena and Miller, 2010), and that motor imagery facilitates corticospinal excitability (Kasai et al., 1997; Facchini et al., 2002). One plausible explanation is that cognitive inhibitory action might be exerted on the motor system (for a review see Aron et al., 2004): the right inferior frontal cortex suppressed electrical activity not only in the basal ganglia (Burman and Bruce, 1997), but also in the motor cortex (Sasaki et al., 1989). "
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    ABSTRACT: Hypnosis often leads people to obey a suggestion of movement and to lose perceived voluntariness. This inexplicable phenomenon suggests that the state of the motor system may be altered by hypnosis; however, objective evidence for this is still lacking. Thus, we used transcranial magnetic stimulation of the primary motor cortex (M1) to investigate how hypnosis, and a concurrent suggestion that increased motivation for a force exertion task, influenced the state of the motor system. As a result, corticospinal excitability was enhanced, producing increased force exertion, only when the task-motivating suggestion was provided during hypnotic induction, showing that the hypnotic suggestion actually altered the state of M1 and the resultant behavior.
    Neuroscience Research 06/2014; DOI:10.1016/j.neures.2014.05.009 · 1.94 Impact Factor
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