Actions can be understood in many ways, from how the action is executed (e.g. action speed) to what the action goals are (e.g. avoiding/approaching), to why the action is performed (e.g. to communicate), and are even influenced by underlying actor traits (e.g. actor dominance).

Together, these behaviours allow us to respond appropriately within our complex social environment. The ability to detect and interpret these behaviours gives a critical insight into the minds of other people. Computational modelling in our lab has shown that there are four key action qualities on which we evaluate human behaviour: friendliness, formidableness, intentionality, and body part movement direction.

This project investigated the sensitivity of individuals with different levels of autistic traits to these action qualities. We were particularly concerned with action friendliness and formidableness as these are thought to be the two most important qualities we need to derive from other peoples’ actions to guide our social interactions with other people. Autistic Spectrum Condition (ASC) can have a profound impact on the ability to interpret social information, but these autistic traits are present in all of us to some extent, as ASC is a spectrum disorder. Although ASC is often associated with psychological deficits, evidence suggests that some aspects of perception are enhanced with ASC. It is therefore important that public awareness of autism includes both the ‘good’ and ‘bad’ of the condition, as well as the nature of the condition as a spectrum on which all humans lie. Hence, our research aimed to test where autistic traits either causes a deficit in, or indeed benefits, the perception of different action qualities. We used a behavioural, computer-based experiment created with Unity.com to accurately measure how well we discriminated action friendliness and action formidableness. 

To do this, we developed an action morphing technique designed to generate novel actions that varied precisely along the dimensions of formidableness and friendliness. In our first experiment, we found that participants rated actions that varied along these continua in a consistent manner, highlighting a clear connection between the novel morphed actions and the level of friendliness or formidableness they were intended to convey (Figure 1).

In the second experiment, we investigated how individuals with different levels of autistic traits perceive these actions using adaptive two-alternative forced choice (2-AFC) tasks. Remarkably, we observed substantial differences in how well participants could distinguish between action formidableness, with a 540% variation among individuals, and even more pronounced differences in friendliness, with a 1100% variation. Intriguingly, this variability in perception did not appear to be influenced by the participants’ level of autistic traits, particularly given that many studies have shown enhancements in visual sensitivity in ASC (Figure 2).

Our results suggest that sensory discrimination enhancements are restricted to simpler, ‘low-level’ stimuli. Despite differences in cognitive styles, individuals can achieve similar performance when it comes to detecting the important social qualities of friendliness and formidableness from actions. These findings add a fresh perspective to the ongoing discussion surrounding the social perception challenges observed in individuals with ASC.