Use of the Peabody Picture Vocabulary Test with the educationally handicapped

Despite widespread use of the Peabody Picture Vocabulary Test (PPVT) as a measure of intelligence for educationally handicapped students, few studies have related PPVT scores of such students to their scores on the Wechsler Intelligence Scale for Children (WISC). Using 100 public school students consecutively referred for learning difficulties, their mean PPVT IQ (97.75) was found to be consistently and significantly higher than WISC Full Scale IQ (89.65), Verbal IQ (88.68), and Performance IQ (92.73). Correlations between the PPVT IQ and the WISC Full Scale, Verbal, and Performance IQs were .70, .69, and .54, respectively. A tabular summary of previous studies comparing PPVT and WISC IQs is included.     

Scoring reliability on the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III)

Nineteen psychologists and 19 graduate students scored two Wechsler Adult Intelligence Scale-Third Edition patient protocols. Mean IQs and indexes were similar across groups, but the ranges for Verbal IQ (VIQ), Performance IQ (PIQ), and Full Scale IQ (FSIQ) on one protocol were 25, 22, and 11 points, respectively. For both protocols taken together, percentages of agreement with the "actual" IQs for psychologists were only 26.3 for VIQ, 36.8 for PIQ, and 42.1 for FSIQ. For students, percentages were 15.8 for VIQ, 23.7 for PIQ, and 31.6 for FSIQ. The percentages of FSIQs that fell within +/- 1 standard error of measurement of the actual IQs were 89.5 for psychologists and 76.3 for students. Scoring error also had a negative impact on index scores. Both groups were confident about their scoring accuracy.     

A systematic literature review of the average IQ of sub-Saharan Africans

On the basis of several reviews of the literature, Lynn [Lynn, R., (2006). Race differences in intelligence: An evolutionary analysis. Augusta, GA: Washington Summit Publishers.] and Lynn and Vanhanen [Lynn, R., & Vanhanen, T., (2006). IQ and global inequality. Augusta, GA: Washington Summit Publishers.] concluded that the average IQ of the Black population of sub-Saharan Africa lies below 70. In this paper, the authors systematically review published empirical data on the performance of Africans on the following IQ tests: Draw-A-Man (DAM) test, Kaufman-Assessment Battery for Children (K-ABC), the Wechsler scales (WAIS & WISC), and several other IQ tests (but not the Raven's tests). Inclusion and exclusion criteria are explicitly discussed. Results show that average IQ of Africans on these tests is approximately 82 when compared to UK norms. We provide estimates of the average IQ per country and estimates on the basis of alternative inclusion criteria. Our estimate of average IQ converges with the finding that national IQs of sub-Saharan African countries as predicted from several international studies of student achievement are around 82. It is suggested that this estimate should be considered in light of the Flynn Effect. It is concluded that more psychometric studies are needed to address the issue of measurement bias of western IQ tests for Africans.     

Clinical use of the Quick Test with sheltered workshop clients

The purpose of this note is to provide clinical reference data on the Quick Test responses of 48 adult sheltered workshop clients. The mean IQs for Forms 1, 2, and 3 were 66.3, 67.6, and 69.7, respectively. The mean IQ for combined Form 1 + 2 + 3 was 68.4. Standard deviations of IQs for the three forms were 13.68, 13.99, and 15.31, respectively, and for Form 1 + 2 + 3 was 13.65. There were 17 females and 31 males ranging in age from 18-2 to 61-1. These data provide tentative local norms for psychologists to use when the Quick Test is given to evaluate mentally subnormal clients of these sheltered workshops for placement or to predict their success in work programs. Future norms should be checked and updated for workshop clients.     

The Flynn effect and U.S. policies: the impact of rising IQ scores on American society via mental retardation diagnoses

Over the last century, IQ scores have been steadily rising, a phenomenon dubbed the Flynn effect. Because of the Flynn effect, IQ tests are periodically renormed, making them harder. Given that eligibility for mental retardation (MR) services relies heavily on IQ scores, renormed tests could have a significant impact on MR placements. In longitudinal IQ records from 9 sites around the country, students in the borderline and mild MR range lost an average of 5.6 points when retested on a renormed test and were more likely to be classified MR compared with peers retested on the same test. The magnitude of the effect is large and affects national policies on education, social security, the death penalty, and the military. This paper reports the perceptions of professionals as they relate to IQ score fluctuations in normal, borderline, and/or MR populations.     

National IQs predict educational attainment in math,reading and science across 56 nations

The results of the 2006 PISA (Program for International Student Assessment) study of reading comprehension, mathematical ability, and science understanding administered to 15 year olds in 56 countries [OECD (2007). PISA 2006: Science Competencies for Tomorrow's World. Paris: OECD.] are examined to assess the predictive validity of the national IQs presented by Lynn and Vanhanen [Lynn, R., & Vanhanen, T. (2002). IQ and the wealth of nations. Westport, CT: Praeger., Lynn, R., & Vanhanen, T. (2006). IQ and global inequality. Augusta, GA: Washington Summit Books.], and to assess the contributions of national differences in IQ and educational variables to national differences in educational attainment. It was found that national scores in reading comprehension, mathematical ability, and science understanding are correlated with Lynn & Vanhanen (L & V) national IQs at 0.84; corrected for attenuation, 0.935. This establishes the high validity of Lynn & Vanhanen national IQs. The contribution of national differences in IQ and education variables to national differences in educational attainment obtained in the 2006 PISA 56 nation study showed that the predictive validity of IQ alone was 0.84, and that national IQs together with one economic and two education variables had the validity 0.90 in predicting PISA 2006 results.     

Validity of the Woodcock-Johnson tests of cognitive ability: A comparison with the WISC-R in LD and normal elementary students

The study addresses the external validity of the Woodcock-Johnson Tests of Cognitive Ability (WJTCA) in learning disabled (LD) elementary school children by controlling for two methodological errors Woodcock identified in previous studies: (a) Intellectual ability range was restricted for both normal and LD samples to counteract an artificial inflation of mean WISC-R scores without concomitant effect on WJTCA scores, and (b) the WISC-R was readministered during data collection. In addition, normals were used as controls for LD students. WJTCA scores were correlated and compared with WISC-R scores and reading achievement test scores in 20 normal, 20 mild-to-moderate LD, and 20 severe LD third-, fourth-, and fifth-grade students. Results indicate comparability of mean WISC-R and WJTCA Full Scale scores in the normal sample, but manifest a significantly lower WJTCA Full Scale scores in the LD samples, despite a strong degree of correlation between the two tests in each sample. The significant linear trend of increasing mean WISC-R/WJTCA discrepancy across the severity of LD strongly suggests that the lower WJTCA scores in the LD samples is a function of the instrument's achievement emphasis and refutes the possibility of systematic error in the WJTCA norms. Results suggest that the WJTCA's achievement emphasis jeopardizes its validity for assessing and classifying LD students within the currently accepted and mandated ability-achievement discrepancy model of specific learning disabilities.     

Studies of socioeconomic and ethnic differences in intelligence in the former Soviet Union in the early twentieth century

This paper reviews the studies of socioeconomic and ethnic and racial differences in intelligence carried out in Russia/USSR during the late 1920s and early 1930s. In these studies the IQs of social classes and of ethnic minorities were tested. These included Tatars (a Caucasoid people), Chuvash and Altai (mixed Caucasoid–Mongoloid peoples), Evenk (a mixed Caucasoid–Arctic people), and Uzbeks (a Central–South Asian people). The results of these studies showed socioeconomic differences of 12 IQ points between the children of white collar and blue collar workers, and that with the exception of the Tartars the ethnic minorities obtained lower IQs than European Russians.     

Recent data for majority and racial minority differences in intelligence of 5 year olds in the United Kingdom

Data are presented from the UK Millennium Cohort Study for a sample of 14,860 5 year old British children giving the IQs of whites and racial minorities. Africans, Indians, Pakistanis and Bangladeshis obtained lower IQs than whites, while the IQ of the Chinese was higher. These group differences in IQ were consistent with the differences in educational attainments and earnings.     

Measuring the importance of cues in judgment for individuals: Subjective theories of IQ as a function of heredity and environment

To measure the relative subjective importance attached to heredity and environment, undergraduates, graduate students, and faculty were asked to predict the IQ scores of hypothetical adopted children based on the IQs of the biological mother and father, the IQs of the adoptive parents, and the socioeconomic status of the adoptive parents. Intuitive predictions of IQ were inconsistent with additive, multiple regression models. Rather, the data for individual subjects were consistent with a configural-weight averaging model. Weights derived from this model were correlated with ratings of the relative importance of cues. Judges who rated the environment more important not only had greater weights for the environmental variables, but also placed greater weight on high rather than low scores. The judges who rated heredity more important than environment had greater estimated weights for heredity information and for lower-valued information. Results were thus consistent with the hypothesis that model-derived relative weights and individuals ratings of the relative importance of cues are both measures of the importance that individuals attach to these cues.     

Relationship of the Wechsler pre-school and primary scale of intelligence and the Stanford-Binet (L-M) in lower class children

Using 72 lower class children, concurrent validity of the WPPSI was studied employing Form L-M of the Stanford-Binet as the criterion. Correlations between SB and WPPSI were moderately high (.86 for FS, .81 for VS, .73 for PS), but the WPPSI appeared a somewhat more difficult test for the sample employed. Mean SB IQ (94.61) was higher than the mean FS (90.71), VS (89.38) and PS (93.68) IQs; it exceeded WPPSI IQ in 72% of all cases. On the WPPSI, PS IQ was significantly greater than either VS or FS IQs. Amont the WPPSI subtests, Vocabulary was significantly lower than all other subtests and Comprehension lower than Picture Completion, Mazes, and Block Design. The only significant sexual difference favored females on Similarities. For subjects whose FS IQ was below the group median IQ, relationships among each of the WPPSI scales and subtests were lower than for those subjects who scored above the median. This was particularly true for the Vocabulary, Animal House, and Picture Completion subtests.     

Heritability estimates versus large environmental effects: the IQ paradox resolved

Some argue that the high heritability of IQ renders purely environmental explanations for large IQ differences between groups implausible. Yet, large environmentally induced IQ gains between generations suggest an important role for environment in shaping IQ. The authors present a formal model of the process determining IQ in which people's IQs are affected by both environment and genes, but in which their environments are matched to their IQs. The authors show how such a model allows very large effects for environment, even incorporating the highest estimates of heritability. Besides resolving the paradox, the authors show that the model can account for a number of other phenomena, some of which are anomalous when viewed from the standard perspective.     

A study of the performance of Egyptian college students on the Advanced Progressive Matrices

Results are reported for intelligence assessed with the Advanced Progressive Matrices of a sample of students at Ain-Shams University in Cairo (N = 2147). The Egyptian raw scores were transformed to British IQ equivalents using the published 1992 British norms for the APM, on which the sample obtained a British IQ of 89.5. Science students obtained a significantly higher average mean score than arts students by 7.5 IQ points. Male students obtained a non-significantly higher average IQ than female students 1.2 IQ points. Male students had greater variability than the female students.     

Discrepancies between premorbid and current IQ as a function of progressive mental deterioration

The declining cognitive functioning typically found in patients with Alzheimer's disease presents an opportunity to study that decline. The changing magnitude of ever widening discrepancies between premorbid estimators of IQ and observed IQ increases as severity of the disease increases. Premorbid IQs estimated by these scores (the National Adult Reading Test-Revised, the reading tests of the Revised and Third Editions of the Wide Range Achievement Test, and a demographically based regression index for the Wechsler Adult Intelligence Scale-Revised) had relatively similar discrepancies from obtained WAIS-R Full Scale IQs in samples of normal elderly (n = 30), and elderly patients diagnosed with mild (n = 30) and moderate Alzheimer's disease (n = 30) dementia. The discrepancies became larger, regardless of premorbid estimator, as disease severity progressed from none to mild to moderate across the samples.     

WORD RECOGNITION SKILLS OF LEARNING DISABLED CHILDREN AND AVERAGE STUDENTS’

Abstract

The ability of learning disabled and average students’ to recognize and identify words was investigated. Two informal reading measures, the Sundbye Minimal Contrast Phonics Test and an oral reading sample, were administered to three groups. The groups were composed of learning disabled students evidencing reading problems (LD), average students matched with the learning disabled group on reading level and IQ (YN), and average students matched with the learning disabled group on chronological age and IQ (ON). The LD group and average readers did not differ on identification of symbol‐sound associations, word recognition proficiency, the ability to detect and correct word recognition errors, and the ability to use information within the text to recognize words. However, the LD and ON group differed on mean number of word recognition errors. Educational implications of the findings were discussed and a profile of the word recognition skills of learning disabled children was presented.     

An electrophysiological study of school-aged children with a history of failure to thrive during infancy.

Sixty-five subjects, ages 8 to 12, participated in a visual electrophysiological study. Twenty-two of the subjects had received a diagnosis of nonorganic failure-to-thrive (FTT) before the age of three. The remaining 43 subjects had no history of FTT and served as Controls. IQs were obtained with the abbreviated WISC-III, and the Controls were split into two groups, LO IQ and HI IQ, to provide a LO IQ Control group with an average IQ equivalent to the FTT group. Event-related brain potentials (ERPs) were recorded from five scalp locations during a cued continuous performance task (CPT). Subjects had to press a button every time they saw the letter "X" following the letter "A" (50 targets out of 400 stimuli). During the CPT, the FTT subjects made marginally more errors of omission to targets than the LO IQ Control group and significantly more errors of omission than the HI IQ Control subjects. The groups did not differ significantly on errors of commission (false alarms) or reaction times to targets. ERP averages revealed a group difference in amplitude in a late slow wave for the 50 non-X stimuli (false targets) that followed the letter A. This difference was greatest over frontal sites, where the FTT group had a more negative going slow wave than each control group. Late frontal negativity to No Go stimuli has been linked with post-decisional processing, notably in young children. Thus, the FTT subjects may have less efficient inhibitory processes, reflected by additional late frontal activation.     

IQ and the wealth of states

In IQ and the Wealth of Nations (2002), Lynn and Vanhanen estimate the mean IQs of 185 nations and demonstrate that national IQs strongly correlate with the macroeconomic performance of the nations, explaining about half of the variance in GDP per capita. I seek to replicate Lynn and Vanhanen's results across states within the United States. I first estimate “state IQs” from the SAT data, and show that the state IQs correlate moderately with the economic performance of the states, explaining about a quarter of the variance in GSP (gross state product) per capita.     

An electrophysiological study of school-aged children with a history of failure to thrive during infancy

Sixty-five subjects, ages 8 to 12, participated in a visual electrophysiological study. Twenty-two of the subjects had received a diagnosis of nonorganic failure-to-thrive (FTT) before the age of three. The remaining 43 subjects had no history of FTT and served as Controls. IQs were obtained with the abbreviated WISC-III, and the Controls were split into two groups, LO IQ and HI IQ, to provide a LO IQ Control group with an average IQ equivalent to the FTT group. Event-related brain potentials (ERPs) were recorded from five scalp locations during a cued continuous performance task (CPT). Subjects had to press a button every time they saw the letter “X” following the letter “A” (50 targets out of 400 stimuli). During the CPT, the FTT subjects made marginally more errors of omission to targets than the LO IQ Control group and significantly more errors of omission than the HI IQ Control subjects. The groups did not differ significantly on errors of commission (false alarms) or reaction times to targets. ERP averages revealed a group difference in amplitude in a late slow wave for the 50 non-X stimuli (false targets) that followed the letter A. This difference was greatest over frontal sites, where the FTT group had a more negative going slow wave than each control group. Late frontal negativity to No Go stimuli has been linked with post-decisional processing, notably in young children. Thus, the FTT subjects may have less efficient inhibitory processes, reflected by additional late frontal activation. *** DIRECT SUPPORT *** A31BB040 00006     

IQ and alcohol consumption : International data

There is evidence at the individual level that alcohol consumption and IQ are positively related: individuals with higher IQ scores tend to consume relatively more alcohol than those with lower IQs. This paper empirically tests whether this relationship holds at the national level. Using national IQ measures and data on per capita alcohol consumption, we test whether higher-IQ countries on average also have higher levels of per capita beer and wine consumption. Based on regression analysis for a sample of 99 countries, the data do not reject the hypothesis that, other factors held constant, higher IQ predicts higher levels of per capita alcohol consumption at the national level.     

Correlations for Wechsler Intelligence Scale for Children--Revised and the Wechsler Preschool and Primary Scale of Intelligence for Iranian children.

This study focused on the relationship between the Wechsler Intelligence Scale for Children--Revised (WISC--R) and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) given to 40 6-yr.-old Iranian children. Pearson correlations between the WISC--R and the WPPSI IQs and between scaled scores on the corresponding subtests were significant. The comparison of mean IQs and scaled scores indicates that the WISC--R yielded a significantly higher Verbal IQ and higher scores on Information, Vocabulary, Comprehension, and Picture Completion than the WPPSI. The mean difference between corresponding Verbal and Full Scale IQs was not significant. These results suggest that scores on the two instruments correlated well for these 6-yr.-old Iranian children and the content on which IQs for the recently restandardized WISC--R and WPPSI are based are related.