Social Seeking Behaviour and Its Neurobiological Correlates

Background:  Evidence suggests that social stimuli are innately rewarding. The reward value associated with social stimuli motivates us to make effort to seek social contacts. The extent to which social stimuli are able to evoke behavioural effort may vary depending on neuro-biological reward responsiveness and individual differences in value assignment to social stimuli. A recent theory suggests that people with autism spectrum disorders (ASD) differ from typical people in their motivation to engage with others (Chevallier et al. 2012). Neurobiological evidence suggests that people with ASD may have differential processing of social stimuli than typicals. The tasks used to measure social motivation in these studies either focus on anticipation or visual preference for social stimuli. However, anticipation or visual preference are conceptually different from social seeking which is described as the behavioural effort made to engage with social stimuli.

Objectives:  This research aims to evaluate social motivation in ASD conceptualized as social seeking i.e. process of making effort to engage with social stimuli. Furthermore, we aim to identify the neurobiological correlates involved in the act of choosing to engage in social interactions.

Methods:  Choose a movie (CAM) paradigm is used to quantify social seeking. CAM measures the behavioural effort (key-presses) people make to look at social or non-social movies. On every trial a choice between stimuli is presented with different levels of effort. Hence participants constantly evaluate the value of social stimuli against effort. In study 1, we evaluated group of adolescents with (N=37) and without ASD (N=31) on CAM paradigm. In study 2, we tested 24 typical adults (13 males) on CAM paradigm while their neural activation was recorded using fMRI.

Results:  Logistic regression was used to predict the role of stimuli, effort and their interaction on participants’ decision to seek social stimuli. Results from study 1 showed that the social seeking behaviour of the ASD group was significantly influenced by the effort and stimuli, but not by their interaction. These results are similar to study 2, in which typical adults were also influenced by the effort and stimuli, but not their interaction. Our imaging results show significant activation in superior-parietal cortex, the area responsible for information integration, while participant made the decision to seek social stimuli. Imaging findings also suggest a significant correlation between strength of effort made to view social stimuli and activation in middle occipital cortex and post central sulcus, indicating differential cognitive processing for effort levels.

Conclusions:  We extend the evidence supporting reduced social motivation in ASD. While people with ASD have lower social motivation, their tendency to seek social interaction may reduce further when higher effort is required. We also present evidence for the differential neural processing in typical adults for effort while seeking social engagement. Overall, our findings indicate that social seeking is a complex process that involves integration of information from various sources such as the subjective reward values and external factors e.g. effort. Each of these factors can influence the social seeking behaviours in people with ASD.