Efference copies are unlikely to play a role in the awareness of one's movement. William James (Reference James1890) recognised that consciousness of movement is an afferent, not efferent, sensation; it is a consequence, not antecedent, of the movement itself. He thought that consciousness of muscular exertion is impossible without movement being effected somewhere. Thus, our awareness of movement is secondary to the actual occurrence of movement in the physical realm. Motor acts enter awareness not at the point of execution, but only as they are perceived. Hurley argues that “copies of motor signals predictively simulate input signals” (sect. 3.3, para. 1). Yet, if motor output were to be unconscious, how could an efference copy of motor output simulate sensory consequences of an action or produce imagery of action effects?

Hurley thinks that through association of an action with its result, we can anticipate the sensory effects of a motor plan. Certainly, what precedes goal-directed action is an “anticipatory image of the movement's sensible effects” (James Reference James1890). Woodworth (Reference Woodworth1926), too, recognised that voluntary action is preceded by imagination of some change to be effected, but he also saw that such imagery of action effects could not amount to the prediction of action effects. The role of what Hurley calls “predictive simulation” may not be to provide feedback onto “input signals” but – by acting as a stimulus – to determine instrumental action in itself. Already James (Reference James1890) considered that thoughts about actions automatically predispose to these actions; indeed, that representations of movement induce the movements they represent. Elsner and Hommel (Reference Elsner and Hommel2001) suggested that perception of an event that resembles a known action effect can automatically activate the corresponding action. Furthermore, imagery of the “intended and expected action effects,” representing the anticipated goal of a voluntary action, can – by acting as a stimulus – elicit the response that produces the “to-be-expected effect” (Elsner & Hummel 2001). Thus, anticipating the consequences of an action may in itself serve as precipitant for action. Imagery of a goal can cause goal-directed action, inasmuch as perception of a goal can have this effect.

There may be no need for a comparator mechanism: Perception and imagery are constructed by attentional mechanisms already in a way that makes them sufficient determinants of motor behaviour in accordance with the situation. In order to determine a motor response, goal perception or imagery is contrasted with awareness of body movement and position (as constrained by reafferent proprioreceptive and visual sensory input). Movement plans (intentions), which specify a target and the movement required to achieve it, are formed automatically – upon perception of salient events – in the posterior parietal cortex, following which they activate connected premotor areas, thus predisposing to a motor response (Colby & Goldberg Reference Colby and Goldberg1999). The representation of a stimulus in the posterior parietal cortex allows premotor areas to determine the coordinates of an action in response to the stimulus, although this does not imply that an action will be produced (Colby & Goldberg Reference Colby and Goldberg1999).

The significance of premotor cortex activation during observation of another's purposeful action (Grezes & Decety Reference Grèzes and Decety2001), which occurs even when the observed interaction is partly hidden from vision and can only be inferred, may be that it produces response facilitation (Rizzolatti et al. Reference Rizzolatti, Fogassi and Gallese2001), which explains our tendency to imitate an observed movement. During observation of goal-directed action, the observer may shift attention to the other's explicit or implicit goal, whereupon the goal is perceived or imagined; which, in turn, primes motor activity instrumental for obtaining the goal. Action understanding was shown to involve activation in premotor areas – more so than the mere imitation of others' actions (Rizzolatti et al. Reference Rizzolatti, Fogassi and Gallese2001). Therefore, understanding of observed action, presumably including understanding of others' speech, involves dispositions to own action.

Many social behaviours are automatically induced by the perception of others' actions (Ferguson & Bargh Reference Ferguson and Bargh2004). People tend to mimic gestures or adopt the accent of a conversation partner without being aware of this. Behaviours in a conversation partner that connote high or low status automatically induce people to adopt opposite postures that connote submissiveness or dominance, respectively (Ferguson & Bargh Reference Ferguson and Bargh2004). Conversational partners use automatic interactive alignment of their response dispositions on multiple linguistic levels – a process that is related to imitation. A speaker's words, sounds, grammatical forms, and meanings activate matching linguistic representations in the partner and thus automatically influence the latter's linguistic productions. Speakers automatically re-use linguistic structures that they have just perceived as listeners (Garrod & Pickering Reference Garrod and Pickering2004).

Hurley suggests that mirroring reverses predictive simulation (Layer 3). Assuming that we simulate “effects of intended acts” (in the sense of anticipatory imagery of a goal for action), can we conclude that “causes of observed movements can be simulated” (target article, sect. 1, para. 9), too? Does perception of another's movement produce simulation in the sense of conscious imagery of a goal or cause of another's action, or does it in itself lead to an automatic disposition to act? Hurley considers that, when observing another's behaviour, the self's matching response is part of the very perception of the other's behaviour. In other words, “a copied motor pattern is part of the perception of another's action, though overt movement may be inhibited” (sect. 2.3.5, para. 6). However, perception of others' behaviour may not give us conscious access to others' goals or motivations, but only indirectly through our automatically elicited behaviour, including verbal expression. Mirrored behaviour may impress after its execution as being in tune with others' attitudes and pursuits, inasmuch as it will also appear to be conforming to the social situation and context in general.

Exposure to others' traits and stereotypes automatically elicits patterns of behaviour and attitude in accordance with the primed traits or stereotypes, whereby subjects are “unaware of any influence or correlation between primes and their behavior” (sect. 2.1, para. 13). Indeed, “thinking about or perceiving action automatically increases, in ways participants are unaware of, the likelihood that they will perform similar actions themselves,” yet why should this process involve copying “at various levels of generality,” particularly the copying of goals (sect. 2.1, para. 14)? Social situations determine our behaviour rapidly and automatically. When we imitate behaviour patterns associated with others' traits and stereotypes, we may do so as a way of seeking social approval, or to display social submission or dominance, although these are by no means explicit goals. Motivation of social behaviour is unconscious and, insofar as one can speak of goals, these are unconscious, too. The absence of explicit goals in patterns of social behaviour raises the possibility that perceived/imagined events or objects generally translate into behavioural dispositions or overt behaviour without preceding reference to goals, meaning that even instrumental behaviour is proximally determined by imagination of some change to be effected, not by explicit goals.

Finally, Hurley argues that mirroring, which produces a “similarity of own and others' acts” (sect. 3.4, para. 9), is prior to the self/other distinction (Layer 4). “Monitoring of output inhibition” is required in combination with simulative mirroring in order to “separate information about others' actions from information about one's own” (sect. 3.4, para. 6). The assumption that “the origin of the self/other distinction” lies in “monitoring whether mirroring is inhibited” (sect. 2.3.5, para 9, emphasis in original) implies that self experience hinges on others' presence and is a social phenomenon even in its most fundamental dimension. It also demands, rather awkwardly, that there should be a fundamental difference between agent/world and self/other distinctions. More parsimoniously, agent/world and self/other distinctions can be conceptualised on a more basic level of sensorimotor control, independently from mirroring (Behrendt Reference Behrendt2005).