Differential Physiological Responses to Appropriate Vs Non-Appropriate Social Stimuli in Neurotypical Adults with Different Level of Autistic and Empathy Traits

Background:  Understanding others’ intentions is evolutionary developed in human and it represents the basic principle of social interaction, for example, pretending not to understand someone’s intentions is considered socially non appropriate. Researches suggest that people with ASD have difficulties in understanding other people’s intentions. However, these social difficulties can be seen as a continuum in the neurotypical population that correlates with the amount of autistic traits. Previous researches underlined how activity in the prefrontal cortex (PFC) plays a role in the attribution of intentions to others. The PFC activity is modulated from subcortical structures (i.e. autonomous nervous system responses) and different physiological responses may be involved while understanding others intentions.

Objectives:  This study aims to test how neurotypical adults with different levels of autistic and empathy traits physiologically respond to socially appropriate stimuli compared to socially non-appropriate stimuli.

Methods:  The experimental procedures were designed measure how components of the autonomic nervous system respond to social and non-social dynamic scenarios (12 videos of 25sec). We employed three convergent methodologies. (i) Physiological assessments of excitability were conducted monitoring cardiac dynamics via Hearth Rate (HR). (ii) Promptness to action was measured as temperature changes on left and right hand; left and right chick and tip od the nose, which are associated with arousal and activation. (iii) Behavioral assessment: adults where asked to judge how predictable and how intelligible the stimuli were. These assessments were performed on neurotypical adults (N=20) with high vs low levels of autistic and empathy traits (measured using: Autism-Spectrum Quotient-ASQ and the Empathy Quotient-EQ).

Results: Analysis revealed that those with a lower AQ and higher EQ had significantly greater HR changes and temperature changes to socially inappropriate stimuli (p<.001), and the higher the EQ, the higher the difference between the judgments of predictability and intelligibility appropriate vs non-appropriate social interactions (p<.001). Using tree-based models we found that the judgments of the level of predictability and intelligibility are mainly accounted for by changes of body temperature in the right side of the body (chick and hand) as well as from the EQ traits. 

Conclusions:  This is the first study to identify the relationship between AQ, EQ and physiological response to dynamic stimuli of appropriate and non-appropriate social interactions. The differential physiological responses to of appropriate and non-appropriate social interactions, suggest that physiological responses may underlie the atypical drive toward non-appropriate social interaction seen in ASD.