Measuring the Reward Value of Various Social Signals in Toddlers with and without Autism: An Interactive Eye-Tracking Study
Objectives: 1) To develop a task measuring the reward value of social signals within different contexts in young toddlers with and without ASD; 2) To test whether toddlers with ASD orient and smile towards social stimuli differently from their typically developing peers depending on the content and predictable nature of social stimuli.
Methods: 118 toddlers at high or low familial risk for ASD took part in the study at 27-month-old and were later characterised at 36-month-old as low risk controls (LR, N=26, age: M=25.6mo, SD=1.1), high-risk with no ASD diagnosis (HR-no ASD, N=78, age: M=26.8mo, SD=1.5), or high-risk with a diagnosis of ASD (HR-ASD, N=14, age: M=26.3mo, SD=1.9). During a gaze-contingent task (Figure1), toddlers could select and trigger one of two different videos through their gaze behaviour. In a first condition, toddlers could activate a video of a person greeting or a musical toy. A second condition contrasted two social stimuli that, when looked at, displayed a person turning either towards or away from the participant. Finally, a third condition contrasted an invariant interaction (a person constantly saying Hello) with a variable interaction (a person either saying Hello, Good job or smiling).
Results: Indexes of reward-seeking behaviour (proportion of first looks and looking time towards stimulus of focus) and an index of hedonic response (proportion of smiles showed in response to the stimulus selected) were analysed (Table1). When the social interaction was predictable, all groups, including the HR-ASD group (no effect of Diagnosis, p>.513), looked longer and smiled more towards a person greeting them compared to a mechanical toy (Condition1, all p<.001) and also smiled more towards a communicative over a non-communicative person (Condition2, p<.001). However, all groups (all p<.018), except the HR-ASD group (p=.507), selectively oriented towards a person addressing the child in different ways over an invariant social interaction (Condition3).
Conclusions: Typical reward-seeking orienting and hedonic response towards predictable social stimuli seem to be present in toddlers with ASD. These results go against accounts suggesting impaired social orienting or diminished motivation to engage with social stimuli. However, the lesser drive towards the variable social interaction observed in toddlers with ASD may reflect either a bias towards more predictable social information or the difficulty to process unpredictable social encounters. These findings suggest that social interaction is intrinsically rewarding for toddlers with ASD, but the specific variability of naturalistic social interactions may modulate the extent to which social exchanges are pursued.