Use of the PPVT-R for Intellectual Screening with Adults: A Caution

Abstract

The present investigation was undertaken to evaluate the construct validity of the PPVT-R as a general screening instrument for intellectual functioning with adults. The sample included 60 normal, neurologically intact adults, aged 18 to 48 years. The PPVT-R correlated positively and significantly (p < .05) with the WAIS-R Full Scale IQ(.47), Verbal IQ(.52), and Performance IQ (.24). Coefficients between the PPVT-R and WAIS-R subtests ranged from .52 (Vocabulary) to − .07 (Digit Symbol). The mean PPVT-R standard score (103.47) was not significantly different than the mean WAIS-R Full Scale IQ (105.38), Verbal IQ(103.90), or Performance IQ (106.33). Cross-tabulation matrices revealed that less than half of the cases were classified correctly by the PPVT-R. Additionally, mean score comparisons within the discrete classification levels revealed that the PPVT-R overestimated the WAIS-R Full Scale and Verbal IQs within the lower ability ranges and underestimated the mean WAIS-R IQs within the upper ability ranges. Regression analyses determined that the PPVT-R was most predictive of the WAIS-R Verbal IQ but only accounted for half of the variance in the Verbal IQ. On the basis of these findings, caution is advised when the PPVT-R is used as a general screening instrument for intellectual functioning.