Date of Completion


Embargo Period



Chi-Ming Chen, Ph.D. and James Green, Ph.D.

Field of Study



Master of Arts

Open Access

Open Access


Diagnosis of Pervasive Developmental Disorder, Not Otherwise Specified (PDD-NOS) is assigned to children who exhibit some of the social and communicative impairments common to children with Pervasive Developmental Disorders (PDD) but fail to meet the detailed criteria of other PDDs. The lack of specific criteria for the diagnosis of PDD-NOS suggests a likely degree of heterogeneity within this population, yet there is little research exploring the similarities and differences between children with PDD-NOS. The current study utilized a hierarchical cluster analysis to detect subgroups within a sample of children with PDD-NOS that provided predictive information about diagnostic outcome at age 4. Results identified three clusters as best fitting the data. Cluster 1 demonstrated the fewest autism symptoms and highest cognitive scores of all clusters. 60% of Cluster 1 children no longer met criteria for a PDD at age 4. Cluster 2 demonstrated more social and communicative impairments and lower cognitive scores than Cluster 1, and the most repetitive behaviors of all three clusters. 89.5% of Cluster 2 children met criteria for Autistic disorder (AD) or PDD-NOS at age 4. Cluster 3 represented a small group of children difficult to diagnose at age two, as these children had the lowest cognitive scores and the most impaired social and communication skills, yet they did not demonstrate repetitive behaviors or interests. 80% of children from Cluster 3 were diagnosed with AD or PDD-NOS at age 4. These results raise questions regarding the increased importance of repetitive behaviors or interests for diagnosing ASD in the DSM-5.

Major Advisor

Marianne Barton, Ph.D.