Efficiency of Peabody Picture Vocabulary in Estimating WISC Scores for Delinquents

Abstract

IQs on the Peabody Picture Vocabulary Test for 106 males 13 to 16 yr. and of lower class status were related to WISC IQs (assessed by student examiners) in three different ranges (80–89, 70–79, Below 70) as a function of race. Both group and individual results were consistent with previous data showing the Peabody scale generally overestimates the IQs of retarded subjects. The present results, however, also indicate that the Peabody tended to underestimate the IQs of 34 “Dull Normal” subjects. Thus, there appears to be an interaction between the Peabody, the WISC, and IQ level. Individual analysis corroborated the group analysis in that 77% of the 26 black subjects and 93% of the 15 white subjects in the range below 70 IQ obtained Peabody scores which overestimated Full Scale WISC IQs. In the “Dull Normal” IQ range the Peabody underestimated WISC performance for 89% of the 18 black subjects and 81% of the 16 white subjects. When the Wechsler mean IQ for both blacks and whites was between 60 and 83 the Peabody tended to produce a mean IQ score between 70 and 78. Thus, irrespective of the Wechsler IQ, the mean Peabody IQ showed little variability. The utility of the Peabody in estimating the Wechsler IQ of juvenile offenders is of doubtful value.

Correlations and factor analysis of the WISC-R and the Peabody Picture Vocabulary Test for an adolescent psychiatric sample.

“…The substantial loadings of the PPVT-B IQ on the two main factors in this study suggest that the PPVT adds little to the knowledge gained from the WISC-R. Although the correlation between the PPVT-B IQ and the WISC-R Full Scale IQ is rather high, studies using other than correlational designs indicated that the PPVT IQ should not be used as an estimate of the WISC-R IQ (see, e.g., Condit et al, 1976).…”

“…Other purposes were to investigate the intercorrelations among the Peabody Picture Vocabulary Test (PPVT) IQ and the WISC-R subtest and summary scores, and to determine whether the PPVT is adding sufficient information to an intellectual assessment battery. The usefulness of the PPVT for predicting Wechsler Intelligence Scale for Children or WISC-R IQs is questionable (Appelbaum & Tuma, 1977;Condit, Lewandowski, & Saccuzzo, 1976).…”

"Input capability and speed of processing in mental retardation": A reply to Stanovich and Purcell.

“…Hornstein and Mosley may have failed to achieve a significant interaction due to limitations of their methodology in making fine group discriminations. Their use of the Peabody Picture Vocabulary Test (PPVT) to discriminate among levels of retardation is questionable (Condit, Lewandowski, & Saccuzzo, 1976). Furthermore, as Galbraith and Gliddon (1972) and Miller, Saccuzzo, & Braff (1979) have shown, a pattern overlapping mask is far more discriminating than the procedure employed by Hornstein and Mosley.…”

“…Hornstein and Mosley may have failed to achieve a significant interaction due to limitations of their methodology in making fine group discriminations. Their use of the Peabody Picture Vocabulary Test (PPVT) to discriminate among levels of retardation is questionable (Condit, Lewandowski, & Saccuzzo, 1976). Furthermore, as Galbraith and Gliddon (1972) and Miller, Saccuzzo, & Braff (1979) Relying on a two-factor theory of visual masking (Spencer & Shuntich, 1970), the critics claimed that i/ Turvey (1973) applies, then the mechanism of masking may have changed from integration to interruption differentially across groups.…”