Sex Differences in Implicit Learning Among Youth with Autism

Background: Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder more common in males than females. It is unclear to what extent impaired social processing in ASD differentially affects females relative to males. One way to examine the impact of social processing on behavior is through implicit learning in social and nonsocial contexts. Previous research suggests that youth with ASD display impaired implicit learning, suggesting poor behavioral control. No research has examined sex differences in implicit learning in ASD. Given that females with ASD may display reduced modulation to social information and experience greater functional impairment than males, females may display reduced implicit learning within social contexts.  

Objectives: We examined sex differences in behavior (error rates, reaction times [RTs]) during an implicit learning task with social (emotive faces) or nonsocial (symbols) performance feedback. First, we examined implicit learning across trials and hypothesized that neurotypical controls would display increased accuracy and RT over time, while youth with ASD would not display behavioral modification across trials. We expected that females with ASD would display significantly reduced behavioral modification relative to males with ASD. Second, we examined the influence of feedback type on implicit learning. We hypothesized that females with ASD, but not males, would display reduced behavioral modification in response to social feedback relative to nonsocial feedback.  

Methods: We collected data from 49 youth with ASD (21 female) and 32 neurotypical controls (15 female) ages 6-17. Behavioral data were collapsed into three blocks to examine learning across the task. Error rates and RTs were examined using Group (ASD, Control) x Sex (Female, Male) x Block (1^st, 2^nd, 3^rd) x Feedback (Social, Non-social) repeated measures ANOVAs.  

Results: For error rates, the main effect of block was significant (F=7.3, p=.001), demonstrating expected increases in accuracy from Blocks 1-3. Main effects of Feedback, Group, and Sex were not significant (Fs<.94, ps>.34). The Block x Feedback x Group interaction was significant (F=6.03, p=.004). Youth with ASD displayed fewer errors for social than nonsocial feedback in Blocks 1-2, but more errors for social feedback in Block 3. Control youth displayed the opposite pattern, with more errors for social than nonsocial feedback in Blocks 1-2, but fewer errors for social feedback in Block 3. No other interactions were significant (Fs<2.6, ps>.08). For RTs, the main effect of block was significant (F=6.0, p=.004), with increasingly faster responses from the Blocks 1-2. Main effects of Feedback, Group, and Sex were not significant (Fs<.71, ps>.40) and no interactions were significant (Fs<2.92, ps>.06). 

Conclusions: Youth with ASD and control youth displayed fewer errors and decreased RTs from the first to third block of the task, indicating intact implicit learning. Contrary to predictions, no Group or Sex differences in implicit learning were observed. However, when considering feedback type, youth with ASD made fewer errors to social feedback early in the task and more errors to nonsocial feedback late in the task than controls, possibly suggesting diminished sensitivity to social feedback. Differential implicit social learning in ASD may contribute to deficits in social processing.