Impaired vitality form recognition in autism

Highlights

• Movements dynamics carry fundamental information for social interaction.

• This information on the agent's internal state is referred to as Vitality form (VF).

• We examined whether ASD individuals detect the VF in two-persons interactions.

• ASD individuals are impaired in VF recognition while recognizing different actions.

• This deficit persists through development thus appearing as an ASD trait marker.

Abstract

Along with the understanding of the goal of an action (“what” is done) and the intention underlying it (“why” it is done), social interactions largely depend on the appraisal of the action from the dynamics of the movement: “how” it is performed (its “vitality form”). Do individuals with autism, especially children, possess this capacity? Here we show that, unlike typically developing individuals, individuals with autism reveal severe deficits in recognizing vitality forms, and their capacity to appraise them does not improve with age. Deficit in vitality form recognition appears, therefore, to be a newly recognized trait marker of autism.

Introduction

The capacity of individuals to attribute goals and intentions to others has been a focus of much research. Many studies were performed in the frame of the so-called theory of mind (Premak & Woodruff, 1978), that is a specific cognitive ability that enables individuals to interpret the behavior of others in terms of mental states such as beliefs and desires (e.g. Baldwin, 1991, Baron-Cohen, 1991, Wimmer and Perner, 1983, Gergely et al., 2002, Meltzoff and Brookes, 2001). A milestone in theory of mind research was the demonstration that typically developing (TD) children are able by 4 years to understand that other people hold beliefs that are recognized as false (Wimmer & Perner, 1983). This finding acquired a particular importance by the discovery that children with autism fail false belief tasks (Baron-Cohen, Leslie, & Frith, 1985). It was therefore proposed that the core deficit in autism is a deficit of theory of mind (Baron-Cohen et al., 1993, Frith, 2003, Leslie, 1987).

More recently, following the discovery of mirror neurons (di Pellegrino et al., 1992, Gallese et al., 1996, Rizzolatti et al., 1996) and the subsequent demonstration that a subpopulation of mirror neurons code agent's intention (Bonini et al., 2011, Fogassi et al., 2005), a series of physiologically-inspired studies, were carried out to assess the capacity of TD children, children with autism (Cattaneo et al., 2007), and, more recently, children with Williams syndrome, to understand actions done by others (Sparaci, Stefanini, Marotta, Vicari, & Rizzolatti, 2012).

The capacity to understand others’ actions is a complex process that requires the capacity to analyse the various action components. A first clear distinction must be made between understanding what the agent is doing (i.e., the goal of the observed action) and understanding why the agent is doing it (i.e., the intention underlying it). For example, when an individual observes another person moving his/her hand towards a mug, he or she immediately understands what the agent is doing (e.g., grasping the mug), but also he might understand why he is doing it (e.g., grasping the mug for drinking or grasping for moving it away). Although these two kinds of action understanding are often strictly intertwined, they appear to rely on different neural mechanisms (see Bonini et al., 2011, Fogassi et al., 2005).

Goal and intention understanding can be found dissociated one from another. Indeed, it has been shown that children with ASD do not differ from TD children when they are asked to recognize what an agent is doing, i.e., the action goal (Boria et al., 2009, Hamilton et al., 2007). In contrast, they are impaired relative to TD children in understanding why an agent is performing a certain action, i.e., in understanding the intention of that action (Boria et al., 2009). More recently, it has been shown that children with Williams syndrome are impaired in understanding what the others are doing, compared to both mental-age and chronological-age TD controls, while they show mental-age appropriate performance in understanding why an individual is acting (Sparaci et al., 2012).

It is worth noting, however, that understanding an observed action does not consist only in recognizing what is the goal of an action and why that action has been performed. There is another fundamental component related to the dynamics of action that is critically involved in warranting social interactions with other people (Stern, 1985). Action dynamics enable the observer to understand the cognitive/emotional state of the agent of the performed action. For instance, a minute variation in the temporal contour, force, or direction of the actions may let the recipient of the action, as well as a neutral observer, to understand whether the agent is gentle or angry, whether he or she performs the action willingly or hesitating, and so on. The dynamics of action carrying this kind of information in a specific stretch of time has been called “vitality affects” (Stern, 1985) or “vitality forms” (Stern, 2010).

As stressed by Stern (2010) the concept of vitality refers to a Gestalt, a spontaneous integration of different dynamic events (movement, force, space, time, direction/intention) that are linked and perceived together in a coherent whole. It constitutes a phenomenal reality that is rooted in physical action but that would nevertheless lose its holistic meaning whenever fragmented into its physical composing elements. The perception of vitality forms is defined as “the felt experience of force in movement with a temporal contour and a sense of aliveness, of going somewhere”“the felt experience of force in movement with a temporal contour and a sense of aliveness, of going somewhere” (Stern, 2010). Regardless of its content (thoughts, actions, emotions), the perceived Gestalt of vitality concerns the specific manner with which dynamic happenings unfold in space and time. It can thus be applied to every dynamic features emerging from the interpersonal relationships or time-based art expressions that “move us by the expression of vitality that resonate in us” (Stern, 2010, pp. 3–17).

There are no experiments that investigated whether individuals with ASD are impaired in understanding “vitality forms”. Some studies showed that children with ASD have difficulties in imitating actions performed with different “styles” (Hobson and Hobson, 2008, Hobson and Lee, 1999). In particular, it was shown that, while children with ASD do not differ from TD children in imitating the goal-directed component of relatively complex actions, they have difficulties in replicating the style (e.g. gentle or forceful) with which the action was demonstrated, especially when imitation of the style was not essential for achieving the action goal. The authors explained the failure of ASD children in incorporating the style of the demonstrator into their own repertoire in light of their weak propensity to identify themselves with others (Hobson, 1989, Hobson, 1993, Hobson, 2002). In conclusion, while it is clear that individuals with ASD often do not use the style of the demonstrator in replicating an observed action, it is still far from clear what might be the cause of this behavior. Is it restricted to the imitation domain? Or does it depend on a more fundamental deficit in recognizing different vitality forms?

To answer these questions we investigated the capacity of individuals with ASD and TD controls to recognize similarities and differences of actions characterized by same or different vitality forms. We will refer to this task as the How Task. Participants were also required to decide whether an observed action was similar or different relative to its goal, regardless of the vitality form with which it was executed. We will refer to this task as the What Task. The results showed a clear dissociation between the two tasks. Individuals with ASD did not differ from controls in the What Task. In contrast, they showed a clear deficit in the How Task. The significance of these findings for a better understanding of social and communicative deficits observed in autism will be discussed.