Date of Completion


Embargo Period



Marianne Barton, Jeffrey Burke, Letitia Nagles

Field of Study

Psychological Sciences


Master of Science

Open Access

Open Access


Recent clinical best-practice guidelines from the American Academy of Pediatrics recommend that all children be screened for ASD at 18 and 24 months of age (Johnson & Myers, 2007), and those have contributed to an emphasis on early screening and diagnosis. However, no screening instrument can identify all cases at 18-24 months. This study examined profiles of 135 children who participated in validation studies of the Modified Checklist for Autism in Toddlers (MCHAT, MCHAT-R/F), an ASD specific screening instrument. Participants were screened at 18-24 months (Time 1) and again at 36-48 months (Time 2). Children who screened negative at 18-24 months old but later screened positive at 30-48 months old (Missed group, N=25) provide important information about the natural course of ASD and potentially about the limitations of early screening efforts. Analyses indicate that child-level variables (adaptive skills, language development milestones) as well as family level variables (maternal education) predicted whether children were missed or detected by an early autism screener. In a combined model, the age at which first words emerged best predicted whether the screener missed a child at 18-24 months. Clinical implications are important to consider in the context of AAP recommendations and a recent focus in the field on universal screening.

Major Advisor

Marianne Barton