Practice Effects on the WAIS-III

Francine D. Carona, Doctoral Student, Clinical Psychology

Fifty-eight participants (age M = 24.59; education M = 14.44 years) were administered the Wechsler Adult Intelligence Scale – Third Edition (WAIS-III) at baseline and at an interval of either 3 or 6 months later. Full Scale IQ (FSIQ), Verbal IQ (VIQ), and Performance IQ (PIQ) scores improved significantly to a commensurate extent at both 3- and 6-month intervals. Specifically, test scores increased approximately 3, 10 and 7 points respectively for VIQ, PIQ, and FSIQ for both groups. These findings suggest that prior exposure to the WAIS-III spuriously increases test scores, regardless of whether retest occurs either 3 or 6 months later. As such, results of reevaluations during these intervals should be interpreted cautiously.