Familiarity and Affect in Adolescents with Autism Spectrum Disorder

Background: In typically developing (TD) individuals, increased familiarity with stimuli generally results in greater affinity toward them. This phenomenon, called the mere repeated exposure (MRE) effect, is robust and pervasive. It has also been found to influence real-world behaviours; specifically, individuals are more likely to approach and less likely to avoid stimuli that have become familiar through MRE. We hypothesized that an abnormal MRE effect would be observed in Autism Spectrum Disorder (ASD) for several reasons, including evidence of: 1) a preference for the familiar in those with ASD, 2) slowed stimulus habituation in individuals with ASD, and 3) atypicalities in the neural reward circuitry of those with ASD, relative to TD comparison participants.

Objectives: The main goal of the current project was to test the hypothesis that the MRE effect would be atypical in individuals with ASD. We also sought to examine the influence of stimulus type (i.e., social vs. non-social) on the MRE effect, as well as the association between the MRE effect and several individual difference variables (i.e., anxiety, intolerance of uncertainty, and restricted and repetitive behaviours).  

Methods: We administered a standard MRE task to 28 12- to 17-year-olds with ASD and 28 age, sex, and IQ-matched TD comparison participants, all with estimated IQs of at least 80. In an exposure phase, participants were shown a series of unfamiliar neutral visual stimuli drawn from three categories at a range of exposure frequencies. In a subsequent rating phase, they were asked to assign liking ratings to both previously-exposed and novel stimuli. Several characterization measures (the Screen for Child Anxiety Related Emotional Disorders, the Intolerance of Uncertainty Scale for Children, and the Repetitive Behaviour Scale - Revised Edition) were also administered.   

Results: A 2 (Diagnostic Group) x 3 (Stimulus Category) x 4 (Exposure Frequency) repeated measures ANOVA revealed a Diagnostic Group x Exposure Frequency interaction [F(3, 52) = 3.07, p = .04; η_p² = .15]. Specifically, while TD adolescents displayed a MRE effect, the liking ratings of participants with ASD did not increase across stimulus presentations, even at the highest exposure frequency. The pattern of liking ratings across exposure frequencies was similar across stimulus categories for both the TD and ASD groups. Few relationships between MRE findings and individual difference variables were observed.

Conclusions: The results of the current study suggest that the relationship between familiarity and affect is disrupted in adolescents with ASD. That is, we observed that TD participants demonstrated rising and then falling liking ratings across a range of stimulus exposure frequencies (i.e., the expected MRE effect), but youth with ASD did not. This pattern of results was similar across three categories of visual stimuli. Additional research will be required in order to clarify whether our findings reflect the protraction or absence of the MRE effect in ASD. These findings provide important insight into one of the processes that may contribute to familiarity preference and novelty aversion in ASD (i.e., a disrupted MRE effect).