Original article Stability of WISC-R scores in students with borderline intellectual functioning

Abstract

BACKGROUND Previous studies on the measurement of intelligence in students with learning difficulties indicate low stability of results observed over time. Therefore, careful analysis of changes in intelligence quotient, as well as in results within Verbal and Performance scale subtests, is necessary. PARTICIPANTS AND PROCEDURE The aim of the research was to analyze changes in WISC-R scores over time in students with borderline intellectual functioning. Test-retest stability of WISC-R was evaluated for Full, Verbal (VIQ), and Performance (PIQ) scales. The study involved 30 students, who were tested three times, when their mean age was 8, 10.8, and 13.6 years old. RESULTS The results showed that Full Scale IQ was fairly stable over time and remained below the average level, between –1.01 and –2.00 standard deviations. Significant changes were observed in the Verbal and Performance scale; VIQ decreased and PIQ increased over time. An initially insignificant statistical difference between the scales grew as time progressed. Furthermore, considerable subtest score fluctuation was observed; over time scores in the Vocabulary subtest significantly decreased whereas in Block Design and Picture Arrangement they increased. CONCLUSIONS The authors argue that delayed acquisition of verbal skills may result from chronic school failure and deficiency of educational support experienced by this group of students. Meanwhile, non-verbal skills, that are less dependent on educational influences and academic knowledge, improve with students’ development through their engagement in everyday life activities.

Keywords

• borderline intellectual functioning
• intelligence quotient
• cognitive profile
• learning difficulties