The relations between joint action and theory of mind: a neuropsychological analysis

Abstract

We examined the relations between joint action and Theory of Mind (ToM) in neurological patients with impairments in ToM, in control patients (who passed ToM tasks) and non-lesioned controls. In two experiments, joint action was assessed in a "social Simon" procedure where spatial compatibility effects were tested under two-alternative forced-choice and under go/nogo conditions, which participants performed in isolation or alongside another participant (the joint action condition). In Experiment 1, patients with impaired ToM showed evidence of increased spatial compatibility effects under standard (two-alternative forced-choice) conditions but, unlike the control participants, these effects disappeared in the joint action condition. In Experiment 2, the ToM patients were asked to pay particular attention to their co-actor. With these instructions, ToM patients with lesions of posterior parietal cortex now showed a sustained spatial compatibility effect in the joint action condition, while ToM patients with lesions primarily involving frontal regions showed an initial effect of spatial compatibility that decreased across trials. The data suggest common processes involved in ToM processing and joint action effects, related to either the ability to attend to appropriate social cues (affected in posterior parietal patients) or the ability to recruit sufficient resources to code another's actions (affected in frontal patients).

Morphometric gray matter differences of the medial frontal cortex influence the social Simon effect

“…Whereas the TPJ, the STS and the temporal poles are generally associated with reasoning about the mental states of self and others, the MFC is assumed to be involved in monitoring and coding one's own and/or other person's action Obhi and Sebanz, 2011) and intentions ). Humphreys and Bedford (2011) provided striking evidence supporting this functional dissociation of frontal and tempoparietal areas in social interactions. Whereas patients with tempoparietal lesion showed consistent SSEs, the SSE decreased over time in patients with frontal lesion.…”

“…Whereas patients with tempoparietal lesion showed consistent SSEs, the SSE decreased over time in patients with frontal lesion. Humphreys and Bedford (2011) argued that patients with frontal lesions seemed to have difficulties in marshaling enough processing resources to maintain the coding of one's own and the other person's action over time.…”

Corepresentation During Joint Action in Marmoset Monkeys (Callithrix jacchus)

“…There is no evidence for corepresentation in 2-to 3-year-old children (Milward, Kita, & Apperly, 2014), but it has been shown in 4-and 5-yearolds (Milward et al, 2014;Saby, Bouquet, & Marshall, 2014), where individual differences are linked to inhibitory control and theory-of-mind abilities (Milward, Kita, & Apperly, 2016). Likewise, Humphreys and Bedford (2011) found no joint effect in patients with theory-ofmind deficits. However, it is also likely that the perception of agency, defined as perceiving an agent as the initiator or causal source of an action, rather than fullfledged intentionality and thus theory of mind, is sufficient for the emergence of a joint Simon effect (Stenzel et al, 2014).…”

The development of co-representation effects in a joint task: Do children represent a co-actor?

“…These behaviours are argued to be achieved through a number of mechanisms, including joint attention, action observation, task sharing, action coordination and understanding of agency (Sebanz, Bekkering & Knoblich, 2006). In turn, mechanisms may be mediated by either lower level processes such as 'mirroring' or simulation (Sebanz & Knoblich, 2009) or higher level mechanisms involving intention understanding and symbolic communication (Humphreys & Bedford, 2011;Atmaca, Sebanz & Knoblich 2011). Either way, joint action requires some form of 'representation' of the basis of a partner's actions, whether this be representing intentions or simply motor schema.…”