Facial expression recognition in the broader autism phenotype: What does alexithymia have to do with it?

Emotion recognition difficulties are widely reported in autism, but the "alexithymia hypothesis" proposes that such deficits are driven by co-occurring alexithymic traits rather than autism itself. We tested this hypothesis in a large sample of 556 adults spanning the broader autism phenotype, using self-reported autistic traits (Autism Quotient, AQ), alexithymia (Toronto Alexithymia Scale, TAS-20), and multiple face processing tasks. All participants completed an emotional expression discrimination task; Subsample 1 (N = 231) additionally completed an expression labelling task and Raven's matrices, while Subsample 2 (N = 325) completed the Cambridge Face Memory Test. Across correlational, regression, partial correlation, and mediation analyses, autistic traits-particularly social-communicative difficulties-were the strongest and most consistent predictors of poorer emotion recognition. In contrast, the core alexithymia facets of difficulty identifying and describing feelings did not contribute unique variance once autistic traits were controlled. Importantly, externally oriented thinking (EOT) emerged as the only alexithymia facet with independent predictive value, consistently associated with reduced accuracy across both emotional and identity face recognition tasks. This suggests that EOT reflects a broader domain-general attentional style that deprioritises reflective engagement with socially salient information. Group-based analyses further confirmed that high autistic trait groups showed significant recognition impairments regardless of alexithymia levels. These findings challenge the alexithymia hypothesis and highlight autistic traits as primary drivers of emotion recognition difficulties, with EOT adding an additional, qualitatively distinct influence. The results call for revised multivariate models of face and emotion processing that integrate autistic traits, attentional orientations, cognitive ability, and gender.