Reliability and validity of Freedom from Distractibility and Processing Speed Factors in the Norwegian WISC-III-version

• Published in: Nordic psychology Vol. 58; no. 2; pp. 136 - 149
• Main Authors: Egeland, Jens, Sundberg, Hilde, Herman Andreassen, Tor, Stensli, Odd
• Format: Journal Article
• Language: English
• Published: Dansk psykologisk Forlag 2006; Taylor & Francis Group
• Subjects: ADHD; Affective Disorders; Attention Deficit Disorder with Hyperactivity; Cognitive Processing Speed; Distractibility; Factor Analysis; Female; Foreign Language Translation; Freedom from Distractibility; Human; Learning Disorders; Male; Processing Speed; Test Reliability; Test Validity; Wechsler Intelligence Scale for Children; WISC-III; ADHD; WISC-III; Factor Analysis; Processing Speed; Freedom from Distractibility
• ISSN: 1901-2276; 1904-0016
• DOI: 10.1027/1901-2276.58.2.136

The reliability and validity of the Freedom from Distractibility (FFD) and Processing Speed (PS) indexes of the WISC-III are controversial. In this first study of the Norwegian translation of WISC-III, 127 protocols from a mixed psychiatric sample were factor-analyzed. Index-scores for subjects with ADHD, Pervasive disorders/nonverbal learning disability, learning disorders, language impairment or anxiety/affective disorders were compared. Results: Only two factors had eigenvalues above 1. They explained 61% of the total variance, thus showing that the WISC-III is primarily a test of a homogenous construct of intelligence. With a more liberal inclusion criteria, the traditional four-factor solution emerged. Comparisons of the four-factor-indexes within each group, showed that the language impaired-group had a significantly lower FFD score compared to the other indexes. The pervasive disorder group was significantly impaired on the PS index. The ADHD group had a flat profile. There was no increased frequency of subjects significantly impaired on the FFD or PS indexes in the ADHD group compared to the other subjects. Conclusion: The study questions the value of the Norwegian version of the WISC-III with regard to assessment of attention and processing speed.