Assessment of Cognitive Abilities in Children with a Pervasive Developmental Disorder Using the Universal Nonverbal Intelligence Test

This study was designed to examine the utility of the Universal Nonverbal Intelligence Test (UNIT; Bracken & McCallum, 1998) for use with children who have been diagnosed with a pervasive developmental disorder (e.g., autistic disorder, asperger’s disorder, pervasive developmental disorder-not otherwise specified). The goal was to determine whether distinct cognitive profiles on the UNIT exist within this population and between those with and without a pervasive developmental disorder: a) Do children with a pervasive developmental disorder earn significantly lower mean scores than a demographically matched control group on the UNIT Full Scale Intelligence quotient? b) Do children with a pervasive developmental disorder earn a significantly higher mean score on the UNIT Nonsymbolic quotient versus the Symbolic quotient? c) Do children with a pervasive developmental disorder earn significantly different mean scores on the UNIT Reasoning and Memory quotients?

Examiners administered the UNIT to 43 children with a pervasive developmental disorder. Data from 31 children who received raw scores of at least 1 on every subtest were used for statistical analyses. Data from an additional 31 children who participated in the UNIT standardization process were also included as the control group. The group with a pervasive developmental disorder had significantly lower scores (p<.001) on every quotient of the UNIT when compared to the control group. When the mean Full Scale Intelligence quotients were compared, the difference of approximately 22 points was significant, t(26) = 4.46, p = .000. Within the group with a pervasive developmental disorder, the mean score of the Nonsymbolic quotient was approximately 4 points higher than the Symbolic quotient; this difference was not significant, t(30) = 1.59, p > .05 (onetailed). When the Memory and Reasoning quotients were compared, the mean difference of .19 was not significant, t(30) = .068, p = .947. Based on mean difference analysis of this sample, there does not seem to be a unique cognitive profile for this population on the UNIT.