Author ORCID Identifier

Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Erin Tone

Second Advisor

Erin Tully

Third Advisor

Lee Branum-Martin

Fourth Advisor

Christine Hall

Fifth Advisor

Lindsey Cohen


The Autism Diagnostic Observation Schedule, 2nd-edition (ADOS-2) Toddler Module is the current gold standard measure of autism spectrum disorder (ASD), a neurodevelopmental condition more frequently diagnosed in toddler boys than in toddler girls. Some evidence suggests that the ADOS-2 Toddler Module diagnostic algorithms may capture an ASD phenotype that is more common among toddler boys than toddler girls. Use of these algorithms may thus contribute to observed sex differences in rates of ASD diagnoses. In particular, the diagnostic algorithms give equivalent weight to social communication items on which boys and girls might be expected to score similarly and items on which girls may, as a function of their early socialization histories, perform better than boys. As a consequence, for girls who do have ASD, algorithm scores may inaccurately fail to reach diagnostic cut-offs.

The current study examined the possibility that some ADOS-2 social communication items may function differently for boys and girls by testing the degree to which eight items equivalently related to the social communication latent factor across sexes in a clinical sample (N=315) of toddlers with suspected ASD. Tests of a series of increasingly restrictive models revealed no evidence of sex differences in the current sample, which was inconsistent with hypotheses. Results suggest that the ADOS-2 Toddler Module assesses these eight items in similar ways for boys and girls. Examination of factor loadings point to Creativity/Imagination as a particular area of interest for future research.


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