The question about the function of conscious intentions cannot be answered by conceptual considerations alone. The status of practical conscious intentions can be analysed in motor action—as it is done by Pacherie as well—but not only on the level of theoretical hierarchical models of motor initiation and control but on a mere neurophysiological level. Let’s begin with a classical example—the Libet-experiments (Libet et al. 1983, 1985) and their modified versions by Haggard & Eimer (1999). Libet and his colleagues designed an experiment to investigate the temporal connection between a voluntary motor activity and the conscious decision—the conscious intention—for this action. They instructed their test persons to voluntarily move their hand and to detect the time at which the urge or the conscious intention to move their hand developed. In parallel, muscle activity was detected via electromyography (EMG) and the readiness potential, a neuronal potential at the beginning of a motor action, was recorded using electroencephalography (EEG). Libet and his colleagues found that the readiness potential can be detected in average 350ms earlier than the test persons experienced the urge to move and postulated that according to this finding the decision to move cannot be causally responsive for the action due to a time-based difference. One interpretation of the experiments is that neuronal activity (the readiness potential for the motor activity) occurs before the conscious knowledge of the action itself. So, the conscious intention itself cannot be responsible for a volitional motor action as it occurs later than the subconscious neuronal changes. These findings initiated an on-going debate about the connection between motor activity and the being conscious about this activity, with many neuroscientists supporting the initial hypothesis. Haggard & Eimer detected a lateralized readiness potential (1999). Libet’s experiment has been replicated in various alternations, supporting the view that conscious intentions follows pre-conscious brain activity fitting to the movement (Trevena & Miller 2002; Siguru et al. 2004; Rigoni et al. 2011). Similar results were shown for the inhibition of an action (Filevich et al. 2013). fMRI studies (Lau et al. 2004; Soon et al. 2008; Haggard 2008) and transcranial magnetic stimulation-studies postulated a neuronal preceding to motor action similar experimental paradigm (for reviews see Haggard 2005; Shields 2014). One recent fMRI-study for example, reported successful prediction of free choices (addition or subtraction) in the study persons due to fMRI data analysis (Soon et al. 2013). Even single-cell recording in humans—as an objective approach to the self-initiated action—detected neuronal recruitment prior to the intention to act (Fried et al. 2011). The conclusion of above-mentioned experiments frequently is, that the conscious intention of a movement is either an illusion or a post-hoc attribution, generated by the movement itself.
On a conceptual level, there exist other models about conscious motor control besides Pacherie’s hierarchical model. An important idea is the idea of intentional binding (Haggard et al. 2002), where an intentional action is causally linked with a certain sensory outcome. In this case, the action and its subsequent effect are perceived as being closer together in time, this generates the phenomenology of causing and independently originating the action, without an actual causal function of the conscious intention. Another current neurobiological theory of motor control is often referred to as comparator model (Frith et al. 2000). Every action consists of two kinds of representations: inverse models that specify motor commands according to sensory perception and forward models that represent the predicted sensory consequences of the movement. When a comparator signals that the sensory consequences of the movement match those predicted by the forward model, we experience this action as consciously intended. Here again, the conscious intention is not causally responsible for the action.
Transferred to the terminology of intentions, this interpretation could mean that a prior intention (or I-intention) cannot be causally responsible for an intention-in-action (lower level intention) as the neuronal activation pattern for the prior intention was earlier detected than the intention was reported as conscious. What would be the conclusion regarding the social creation myth? As a conscious intention itself—according to the above mentioned interpretation—is not regarded to be causally responsible for the initiation of a motor activity (only the subconscious neuronal activity is responsible) the conscious mental representation of a motor activity in individual or joint action is not causally involved in the processes of motor control. The function of conscious intentions in the social creation myth either stays a myth, as it contradicts the empirical findings, or the myth fits the nature of conscious intentions and we have to reconsider the interpretation of the experiments.
To support the later alternative, one recent study using transcranial magnetic stimulation, a method which allows generating movements by transcranial stimulation of the neurons of the motor cortex, postulated that motor activity is initiated by conscious intentions. A transcranial stimulus was set in the right motor cortex and introduced a tiny muscle twitch, only recordable by EMG. When test persons intended to move their left hand prior to the transcranial stimulus, the transcranial-induced involuntary movement induced a stronger visible motor response. The authors postulated that the conscious intention prepares volitional motor actions by increasing the excitability of the cells in the motor cortex that can produce the movement intended (Zschorlich & Köhling 2013).
There are further some major limitations to the studies, e.g., the subjectivity of the report of the urge to move, and the highly artificial/constructed experimental situation in which the intentional action is carried out. One common objection against an interpretation of the data in the way of Libet and colleagues is that conscious intentions (e.g., the prior intentions) are not comparable to the urge to move in an experimental setting but rather are comparable to the decision to participate in the whole experiment. The urge to move would rather be an intention-in-action and by this not comparable to a conscious deliberation about an action. Following from the data, a conscious intention is unnecessary or irrelevant (as it occurs “too late”) in conscious motor initiation and control could be a too far-reaching conclusion.