A COMPARATIVE STUDY OI? WPPSI AND WISC PERFORMANCES OF DISADVANTAGED CHILDREN’

ALLAN C. YATER MILLER BOYD AND ALLAN RARCLAY

Saint Louis Utiiuersity

PROBLEM Recent research in intellectual development has focused upon the preschool

years, particularly among children from disadvantaged backgrounds. In view of the many advantages of the WISC, and its extensive research literature, i t has been adopted by practitioners who seek a valid and reliable instrument for individual assessment and screening purposes among disadvantaged children. However, since the standardization sample of the WISC contained neither disadvantaged nor black Ss, use of the WISC with such a population has been que~t ioned‘~’ p p . 480-

The publication of the WPPSI(7) , a test standardized on a sample that included disadvantaged black children, provided an instrument seemingly more appropriate than the WISC for use with children from such backgrounds. The purpose of this cross-sectional study was to compare and contrast performances on the WPPSI and the WISC to determine the concurrent validity of the two instruments a t three age levels among disadvantaged black chilren.

481).

RJETHOD

Subjects . A total of 60 black, disadvantaged children (20 from Head Start preschool, 20 from Follow-Through kindergarten, and 20 from Follow-Through first grade) were selected from Head Start and Follow-Through programs con- ducted in a single metropolitan area. All children in the kindergarten and first- grade groups had previous Head Start experience. Sexes were equally represented with 10 boys m d 10 girls in each of the three groups. Chronological age (CA) ranged from 60 to 68 months (x = 63.45; SD = 1.00) in the Head Start preschool group, from 62 t o 79 months (x = 65.15; SD = 6.14) in the Follow-Through kindergarten group, and from 73 to 95 months (x = 80.50; SD = 5.16) in the Follow-Through first-grade group (Table 1). TAnLir 1. MIUNS AND STANDARD ~)b:VIATIONS FOR wPP8I AND WISC I& ESTIMATICS AND CA FOR

PRKXHOOL, KINDERGARTEN, A N D FIRST-GRADI~: GROUPS

Preschool Kindergarten First Grade (N = 20) (N = 20) (N = 20)

I& x SD x SD x SD

WPPSI V - I& 92.36 12.94 95.66 8.45 91.11 12.07 WPPSI P - IQ 02.76 14.12 98.66 17.36 91.41 15.02 WPPSI FS - IQ 91 .86 13.32 96.76 12.87 90.36 13.85 WISC V - I & 95.46 15.69 89.21 11.34 87.91 9.63 WISC P - I & 97.11 20.46 97.51 12.23 91.05 8.91 WISC FS - I& 96.05 17.87 92.41 11.06 88.30 8.78 CA 63.45 1.00 68.15 6.14 80.50 5.16

Procedure. All children were administered the WISC and the WPPSI according to the instructions presented in the respective manuals(6* ’). Ten subtests of the WISC were administered in the recommended order, while 2 subtests, digit span and mazcs, were excluded. Ten subtests of the WPPSI also were administered in the suggested order; the omitted subtests were Sentences (Supplementary) and Animal House Retest. The two instruments were presented in the following sequences: prcsch(,ol-couriterbalanccd ; kindergarten-WPI’SI first, WISC second ; first-gradc

’Grateful acknowledgement is made to S. J. Anderman for assistance in the execution of this project.

A COMPARATIVE STUDY OF WPPSI AND WISC PERFORMANCES 79

-WISC first, WPI’SI second. There was an interval of approximately 2 weeks between sessions.

Examiners in the preschool group were two white males. In the kindergarten and first grade groups, examiners were one black female, one white male, and two white females. All examiners were graduate students experienced in the admini- stration of the Wechsler tests. All S s were tested in their respective Head Start centers or schools.

RESULTS Within all three groups, no sex differences were found between Verbal, Per-

formance, and Full-Scale IQs on either the WPPSI or the WISC. Therefore the sex groups were combined for the following analyses. Within the Head Start pre- school sample, the WISC IQs consistently overestimated the WPPSI Verbal, Performance and Full Scale IQs, but these differences were not statistically sig- nificant (Table 1).

At the kindergarten level the WPPSI consistently overestimated the WISC IQs. The WISC Verbal I& (x = 89.21; SD = 11.34) and Full-scale IQ (x = 92.41; SD = 11.06) were significantly lower (t = 3.60, df = 19, p < .001; t = 2.46, df = 19, p < .05) than the WPPSI Verbal IQ (x = 95.66; SD = 8.45) and Full-scale I& (x = 96.76; SD = 12.87). No significant differences were found between WPPSI- WISC Performance and Full-scale IQs. Comparison of I& scores among the three groups indicated no significant differences, although the first-grade group tended to be lowest. Table 2 presents the intercorrelation coefficients for WPPSI and WISC Verbal and Performance IQs for the three groups. The most substantial and con- TABLE 2. INTERCORRELATION COEFFICIENTS OF WPPSI AND WISC VERBAL AND PERFORMANCE

IQS

Preschool Kindergarten First Grade (N = 20) (N = 20) (N = 20)

WPPSI VIQ - WISC VIQ .79** .71** .go** WPPSI PI& - WISC PIQ .77** .72** .58** WPPSI VIQ - WISC PI& .64** ,44* .48*

WPPSI VIQ - WPPSI PI& .63** .65** .72** WISC VIQ - WISC PIQ .62** .44* .48*

WPPSI PI& - WISC VIQ .51* .52** .45*

* = < .05; ** = p < .01.

sistent relationship between the instruments was found on the Verbal scale for all three groups. It was found that the two Verbal scales shared about 50% to 64y0 of common variance. Correlations between WPPSI and WISC Performance IQs dropped considerably in the first-grade group. For the preschool and kindergarten levels, the Performance scales on the two instruments shared approximately 51% to 59y0 of common variance; in the oldest group, however, only 340/, of the variance was in common. Comparisons of the Verbal and Performance scales across instru- ments yielded, in the main, moderate correlation coefficients.

Within instruments, WPPSI Verbal and Performance scales were found to correlate at a moderate, but significant degree in all three groups. WISC Verbal and Performance IQs correlated moderately and significantly only in the preschool group.

DISCUSSION The mean I& scores on the WPPSI and the WISC were obtained in a cross-

sectional study of three samples of black, disadvantaged children that differed in grade and age. No significant differences in I&, as estimated by either the WPPSI

so ALLAN C. YATER, MILLER BOYD AND ALLAN BARCLAY

or the WISC scales, were found among preschool, kindcrgarten, and first-grade groups. This is in contrast to the findings of Deutsch and who studied children of similar background and ages and found a significant decrease in I& with grade level. Furthermore, the major portion of the I& scores in the present study fell within the low to mid-average range, a finding consistent with an earlier report by Barclay and Yater‘l), who studied children from the same urban area as the present investigation.

The phenomenon of “cumulative deficit”@* pp. 89-100) was not observed in this study. A possible explanation may be that the previous investigator followed Head Start children who moved into regular elementary public school programs that did not provide continuing stirnulation and enrichment to build upon the preschool experience. In contrast, the children in this study continued their Head Start experience by moving into Project l~ollow-Through, which continued to provide enriched stimulation. Perhaps i t is this continued emphasis on enrichment that may account for the present findings, which provide support for Gordon’s (4 )

hypothesis as to the necessity for good educational experiences in the subsequent elementary school years in order t o provide stable cognitive development.

It is interesting to note that the mean I& estimates yielded by the WI’PSI arid the WISC scales in all three groups fell below the normative mean of the standardization samples. Since the WPPSI standardization sample included black, disadvantaged children, while that of the WISC did not, cultural bias effects with the WPPSI would not be expected to be operative. However, cultural bias does not seem to be controlled by including cultural minorities in national stand- wdization samples, because these results indicated a high correlation between the two scales and the WPl’SI mean scores fell below the national norm. This finding, then, points up the necessity for development of standardization tables reflective of the particular cultural and demographic characteristics of the sample to be evaluated.

Interpretation of the results of this study is limited to the extent that the design did not allow for the investigation of test presentation order effects, nor for the effects of examiner sex arid ethnic background on test performances. It is believed that these limitations were minimized by the lack of significant differences between I& estimates for the two scales. These findings suggested that the order effects were not a factor that influenced test results. Examiner sex and ethnic effects also were considered to be noninfluential due to these nonsignificant findings.

SUMMARY The present study investigated the WPPSI and WISC porformarices of black,

disadvantaged children, both male and female. Findings were: (1) that there wcrc no sex differences for cither the WPPSI or the WISC; (2) that the WPPSI con- sistently overestimttted the Verbal and I’ull Scale I& obtained from the WISC; and ( 3 ) that therc were no significant WPPSI-WISC differences for Performance

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I . BARCLAY, A. and YATER, A. C. Comparative study of the Wechsler Preschool and Primary Scale of Intelligeiwe and the Stanford-Binet Intelligence Scale, Form L-M, among rtili,urally deprived children. J . c o i ~ & . diu. I’sychol., 1!)69, 33, 257.

2. DMJTSCH, M. Early social environment: Its influence on school adaplation. In Shreiber, D. (Ed.) The School Dropout.

3. DWTSCH, M. and BROWN, B. Soc.ial inflriences in Negro-white intelligence differences. J .

4. GorzDoN, E. What did we learn? Amer. Chzld, 1906, 48, 1 1 . 5. MCCANU~~ESS, B. 13. Review of the WISC. In BUitos , 0. K. (Ed.) Fourlh Me?tlal Measurements

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