Doctoral Dissertations

Date of Award

8-2008

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Education

Major Professor

R. Steve McCallum

Committee Members

Sherry Bain, Joel Diambra, John Lounsbury

Abstract

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.

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