Vocational Rehabilitation of the Socially Disadvantaged: Demographic and Intellectual Correlates of Outcome

Data are reported relating various demographic and intelligence attributes of socially disadvantaged clients to successful or unsuccessful outcome of a comprehensive vocational assessment and guidance program. Mothers of illegitimate children tended to complete the assessment program but to remain unemployed. Age was positively related to success, whereas education was unrelated. Verbal and performance IQ were positively related to outcome for females. Successful Caucasian males were higher in verbal IQ than successful male Caucasians, but no difference was found for Negro males. Performance IQ was nonpredictive of outcome for both white and Negro males. Higher verbal than performance IQ was positively correlated with success for male Caucasians.     

Working memory, reading, and mathematical skills in children with developmental coordination disorder

The aim of the present study was investigate the relationship between working memory and reading and mathematical skills in 55 children diagnosed with developmental coordination disorder (DCD). The findings indicate a pervasive memory deficit in all memory measures. In particular, deficits observed in visuospatial short-term and working memory tasks were significantly worse than in the verbal short-term memory ones. On the basis of these deficits, the sample was divided into high and low visuospatial memory ability groups. The low visuospatial memory group performed significantly worse on the attainment measures compared to the high visuospatial memory group, even when the contribution of IQ was taken into account. When the sample was divided into high and low verbal working memory ability groups, verbal working memory skills made a unique contribution to attainment only when verbal IQ was taken into account, but not when performance IQ was statistically controlled. It is possible that the processing demands of the working memory tasks together with the active motor component reflected in the visuospatial memory tasks and performance IQ subtest both play a crucial role in learning in children with DCD.     

Reaction time correlations with intelligence test scores obtained under either timed or untimed conditions

One hundred and thirteen high school students were randomly assigned to one of two groups that were administered an intelligence test (the Multidimensional Aptitude Battery) under either timed or untimed conditions. Subsequently, all subjects were given a battery of 8 reaction time tests. Multiple regression analyses showed that combinations of RTs were approximately equally good predictors of IQ scores in both groups. Zero-order correlations between each RT test and IQ scores were also approximately equal for timed and untimed Verbal and Full-Scale scores but correlations with Performance scores were higher in the timed condition. The extent to which the different RT tests correlated with timed scores was quite highly related to the tests' loadings on a general speed factor but these loadings were not related to the tests' correlations with untimed scores. Rather, the relative complexity of the RT tests had a stronger influence on their correlations with IQ scores in the untimed condition. It is concluded that timed and untimed intelligence tests impose different information-processing demands on subjects but that the speed with which subjects can cope with these demands is equally important in both conditions.     

Working memory resources in young children with mathematical difficulties

Kyttälä, M., Aunio, P. & Hautamäki, J. (2010). Working memory resources in young children with mathematical difficulties. Scandinavian Journal of Psychology, 51 , 1–15.
Working memory (WM) ( Baddeley, 1986, 1997 ) is argued to be one of the most important cognitive resources underlying mathematical competence ( Geary, 2004 ). Research has established close links between WM deficits and mathematical difficulties. This study investigated the possible deficits in WM, language and fluid intelligence that seem to characterize 4- to 6-year-old children with poor early mathematical skills before formal mathematics education. Children with early mathematical difficulties showed poor performance in both verbal and visuospatial WM tasks as well as on language tests and a fluid intelligence test indicating a thoroughly lower cognitive base. Poor WM performance was not moderated by fluid intelligence, but the extent of WM deficits was related to language skills. The educational implications are discussed.     

Does relocating information in text depend on verbal or visuospatial abilities? An individual-differences analysis

In this individual-differences study, we evaluated the prevalent view that relocating information in a previously read text depends primarily on visuospatial abilities. Participants read a text, answered fillin-the-blank test questions, and identified which page and line in the original text contained the sentence in each question. They also completed a battery of verbal and visuospatial tasks. Performance on verbal tasks was highly predictive of the accuracy of both page and line identifications, and this correlation remained significant even after we controlled for performance on visuospatial tasks. In contrast, performance on visuospatial tasks was not predictive of either page or line identification accuracy, once verbal abilities were controlled for. These results suggest an important role for verbal abilities in relocation of text information and a lesser role for visuospatial abilities than has previously been assumed.     

Dynamic spatial performance and general intelligence

A computerized video-game-like dynamic spatial ability measure and a paper-and-pencil group test of intelligence were administered to 94 university students. The purpose of the study was threefold: (a) to evaluate the reliability of the dynamic spatial measure; (b) to investigate the extent to which the dynamic spatial measure is saturated with variance associated with traditional measures of fluid and crystallized intellectual ability; and (c) to explore the possibility that dynamic computer based performance measures define factors that are distinct from those associated with traditional paper-and-pencil measures. The number of times the participant hit a moving target served as the dependent variable for the dynamic spatial measure. Number of hits proved to be correlated with Performance IQ, but was not significantly correlated with Verbal IQ. Maximum likelihood factor analysis revealed that the dynamic spatial measure did not load substantially on a factor of general intellectual ability but provided additional evidence that it is related to a performance component.     

Differential construct validity of intelligence as popularly measured: Correlations of age with raw scores on the WISC-R for Blacks Whites, males, and females

Raw scores on the 12 WISC-R subtests and the verbal, performance, and full scale IQ scales were correlated with age in years separately for 938 White males, 137 Black males, 927 White females, and 153 Black females. Highest and lowest correlations from the four groups were then contrasted for each of the 15 WISC-R variables to determine whether the magnitude of the relationship between age and performance on current tests of intelligence is constant across race and sex. Regression coefficients between age and raw scores were also contrasted across groups. None of the 15 comparisons of corrections yielded differences that were statistically significant. Regression coefficients differed only with respect to the Full Scale IQ, showing smaller incremental changes with age for Black males than for other groups. The results indicated that the relationship between age and intelligence test performance is relatively constant across race and sex and supports the construct validity of the WISC-R as a measure of children's intelligence for Blacks, Whites, males, and females, though some evidence was found to indicate slower development of “g” in Black males as compared to the other groups.     

Individual differences in proactive interference in verbal and visuospatial working memory

Proactive interference (PI) has been shown to affect working memory (WM) span as well as the predictive utility of WM span measures. However, most of the research on PI has been conducted using verbal memory items, and much less is known about the role of PI in the visuospatial domain. In order to further explore this issue, the present study used a within-subjects manipulation of PI that alternated clusters of trials with verbal and visuospatial to-be-remembered items. Although PI was shown to build and release across trials similarly in the two domains, important differences also were observed. The ability of verbal WM to predict performance on a measure of fluid intelligence was significantly affected by the amount of PI present, consistent with past research, but this proved not to be the case for visuospatial WM. Further, individuals’ susceptibility to PI in one domain was relatively independent of their susceptibility in the other domain, suggesting that, contrary to some theories of executive function, individual differences in PI susceptibility may not be domain-general.     

Inferior Parietal Perfusion, Lateralization, and Neuropsychological Dysfunction in Alzheimer's Disease

The severity of inferior parietal perfusion deficits in Alzheimer's disease (AD) is strongly associated with global intellectual decline. The relationship to specific losses of neuropsychological functioning, however, is less clear, as is the relative importance of the side (left vs. right) of hemispheric deficit. In this study, 53 patients with probable AD and 35 elderly controls received both a resting¹³³Xe rCBF measurement and neuropsychological examination. AD patients demonstrated the expected bilateral deficits in inferior parietal perfusion, as well as impairment on measures of mental status, intelligence, verbal and visual memory, attention, language, and construction abilities. The severity of this bilateral parietal deficit, in turn, was associated with virtually all of these AD-related neuropsychological impairments, most strongly with declining Performance IQ. Left-sided deficits correlated better with overall declines in IQ, as well as with declining attention and language fluency. Right-sided deficits, on the other hand, correlated best with declines in mental status and—paradoxically—verbal memory and contributed independently to declines in Full Scale and Performance IQ. In terms of the number and strength of their association to neuropsychological measures, left-sided deficits appear much more predictive of cognitive decline in AD. Right-sided deficits, however, may be most important for predicting aspects of performance skill that are only indirectly assessed in standard paper-and-pencil format. Overall, it appears that both sides make significant, but independent contributions to general functional decline in AD, but that left-sided deficits are more closely associated with cognitive decline as measured by most standard neuropsychological measures.     

Changing abilities in recognition of unfamiliar face photographs through childhood and adolescence: Performance on a test of non‐verbal immediate memory (Warrington RMF) from 6 to 16 years

A commonly used test of non‐verbal memory, which measures recognition for unfamiliar face pictures, was developed by Warrington (1984) , the Recognition Memory for Faces (RMF) test. The task has been widely used in adults in relation to neurological impairment of face recognition. We examined the relationship of RMF scores to age in 500 young people aged between 6 and 16 years. A linear relationship obtained between 6 and 10 years, followed by a ‘plateau’ between the ages of 10 and 13, followed by further improvement. Abilities on the test correlated with both verbal and non‐verbal intelligence, but the nonlinear function relating age and RMF survived partialling for intelligence in the younger age groups. The improvement of the adolescents compared with older children also survived partialling for IQ. We found no significant influence of gender or reported pubertal status (which was not obtained for all participants) on RMF once age was taken into account. Performance on other face‐processing tasks (emotion classification and accuracy in line of sight detection) correlated significantly, if moderately, with RMF scores. Despite its age and imperfections, RMF test may nevertheless be a useful indicator of ‘face expertise’ in a developmental context.     

The relationship between WAIS-R abilities and speed of processing in a word identification task

Matched to the proportions found in the U.K. census data for a range of demographic variables (age, sex, and socioeconomic status) 123 participants were tested on the Wechsler Adult Intelligence Scale-Revised (WAIS-R) and a test of the minimum presentation time required to identify tachistoscopically presented words. The correlations between the sum of the scaled scores for Full, Verbal, and Performance subtests and the log of the identification measures were -0.40, -0.22, and -0.51, respectively. These results are in line with those observed between the WAIS-R measures and standard visual inspection time (IT). Confirmatory factor analysis indicated that a three-factor model of intelligence with Verbal, Performance, and Attention/Concentration factors, and with the identification threshold loaded on the Performance factor alone, represented a better fit to the data than either a single general factor model or a two-factor model with Verbal and Performance factors. These results are in line with findings in the IT literature (Deary, 1993) that speed of information processing is significantly related to performance IQ but not to verbal IQ.     

Neuropsychological assessment in illiterates: visuospatial and memory abilities

A basic neuropsychological battery of visuospatial and memory abilities was administered to extreme educational groups (illiterates and professionals). Subjects were matched according to sex and age. The following visuospatial tasks were included: figure copy (cube, house, and Rey-Osterrieth complex figure), telling time, recognition of superimposed figures, recognition of a map, and drawing of the plan of the room. The following memory tasks were used: basic information, digit retention (forward and backward), memory curve, delayed verbal recall, sentence repetition, logical memory, delayed logical memory, immediate recall of the Rey-Osterrieth complex figure, immediate reproduction of a cube, visuospatial memory, and sequential memory. In visuospatial tasks all differences between the two groups were statistically significant. Five of the seven visuospatial tasks (all but telling time and recognition of superimposed figures) showed differences between age groups with a better performance found in the younger groups and four of the tasks (cube, house, Rey-Osterrith complex figure copying, and telling time) were significant between sexes with a better performance in men. In memory tasks, with the exception of the immediate memory of sentences, all tasks showed statistically significant differences between educational groups. Eight of the 13 memory tasks (digits forward and backward, delayed memory of words, immediate and delayed logical memory, Rey-Osterrieth immediate memory, cube immediate memory, and sequential memory) showed significant differences for age while 4 of the tasks (digits backward, memory curve, Rey-Osterrieth immediate memory, and cube immediate memory) were significant for sex. Results are analyzed with regard to current theories in cognitive psychology and anthropology. Emphasis is placed on the finding that cognitive skills usually examined by neuropsychological tests represent learned and highly trained abilities.     

The comparability of intelligence test results: Group- and individual-level comparisons of seven intelligence tests

A significant body of research has demonstrated that IQs obtained from different intelligence tests substantially correlate at the group level. Yet, there is minimal research investigating whether different intelligence tests yield comparable results for individuals. Examining this issue is paramount given that high-stakes decisions are based on individual test results. Consequently, we investigated whether seven current and widely used intelligence tests yielded comparable results for individuals between the ages of 4–20 years. Results mostly indicated substantial correlations between tests, although several significant mean differences at the group level were identified. Results associated with individual-level comparability indicated that the interpretation of exact IQ scores cannot be empirically supported, as the 95% confidence intervals could not be reliably replicated with different intelligence tests. Similar patterns also appeared for the individual-level comparability of nonverbal and verbal intelligence factor scores. Furthermore, the nominal level of intelligence systematically predicted IQ differences between tests, with above- and below-average IQ scores associated with larger differences as compared to average IQ scores. Analyses based on continuous data confirmed that differences appeared to increase toward the above-average IQ score range. These findings are critical as these are the ranges in which diagnostic questions most often arise in practice. Implications for test interpretation and test construction are discussed.     

Word identification in adults with mild mental retardation: does IQ influence reading achievement?

OBJECTIVE: To assess the relationship between word identification and intelligence in adults with mild mental retardation (IQ < 80). METHOD: A standardized evaluation was administered to 67 adults with mild mental retardation. The evaluation included a psychiatric interview, the WAIS-R, and a 2-h interview with a speech therapist and reading tests. RESULTS: Causes of mental retardation were diverse in the sample, and IQ scores ranged from 43 to 79 (mean score = 64). All subjects exhibited reading impairment, including 69% with severe impairment. No subject with an IQ score under 65 was able to perform adequately in the word identification tasks. Word identification was correlated with total and verbal IQ, but not with performance IQ. CONCLUSION: Our results suggest that, in contrast to subjects with normal intelligence, IQ score is correlated with reading in subjects with mild mental retardation. Finally, remediation should be preferentially implemented for subjects with IQ score greater than 65.     

Working Memory and Cognitive Skills in Individuals with Down Syndrome

This work is aimed at analyzing working memory (WM) components and their relationships with other cognitive processes in individuals with Down syndrome (DS). Particular attention is given to examine whether a verbal WM deficit is due to difficulties in verbal abilities often showed by individuals with DS, or whether it is a deficit per se. A group of 20 individuals with DS was compared to a group of 20 typically developing (TD) children matched on vocabulary comprehension and to a group of 20 TD children matched on general verbal intelligence. The groups received a battery of 3 verbal and 3 visuospatial WM tasks requiring different degrees of control, and tests assessing verbal abilities (WPPSI verbal scale, PPVT), nonverbal skills (WPPSI performance scale), and logical thinking (LO). The results revealed that individuals with DS have deficits in both central executive (control) and verbal components of the WM system, and the latter one is independent of the general verbal abilities deficit. The data suggest that the development of central executive proceeds at a slower rate in individuals with DS and differently from TD children with comparable verbal abilities. The performance of individuals with DS on high-control WM tasks requires additional general resources that are strictly linked to intelligence.     

Visuospatial working memory in Turner's syndrome

Turner's syndrome is a genetic disorder, specific to women, in which one of the X chromosomes is partially or completely deleted. This syndrome is associated with physical features such as short stature or failure in primary and secondary sexual development, together with a specific pattern of cognitive functions. It has been suggested that women affected by Turner's syndrome perform poorly in tasks measuring visuospatial abilities and have a verbal IQ significantly higher than performance IQ. Although this result has received strong empirical support, the nature of the visuospatial deficit is still unclear. Recent studies on visuospatial processes have highlighted that the underlying cognitive structure is more complex than previously suggested and several dissociations have been reported (e.g., visual vs spatial, sequential vs simultaneous, or passive vs active processes). In the present study we analyze in detail the characteristics of the visuospatial deficit associated with Turner's syndrome by presenting four young women with a comprehensive battery of tasks designed to tap all aspects of visuospatial working memory. Results confirm that Turner's syndrome is associated with a general visuospatial working memory deficit, but the pattern of performance of different cases can be different, with a greater emphasis on active visuospatial processes. and on either sequential or simultaneous spatial processes.     

Cross-linguistic assessment of verbal production from a narrative task in Williams Syndrome

Williams Syndrome (WS) is a disorder caused by a delection in chromosome 7, with a cognitive profile characterised by mild to moderate mental deficiency and difficulties in visual-spatial processing, which contrasts with a relative preservation of linguistic functions and narrative production. In this study, verbal performance was analysed in two groups of participants (N = 3), Portuguese and Spanish, genetically diagnosed with WS. Scores were low in Verbal IQ, as in Performance IQ. Narrative performance showed low coherence with respect to structure, process, and content. WS verbal performance was affected and there was no difference between both groups. We could not find any dissociation between cognitive functioning and linguistic production.     

The impact of culture and education on non-verbal neuropsychological measurements: a critical review

Clinical neuropsychology has frequently considered visuospatial and non-verbal tests to be culturally and educationally fair or at least fairer than verbal tests. This paper reviews the cross-cultural differences in performance on visuoperceptual and visuoconstructional ability tasks and analyzes the impact of education and culture on non-verbal neuropsychological measurements. This paper compares: (1) non-verbal test performance among groups with different educational levels, and the same cultural background (inter-education intra-culture comparison); (2) the test performance among groups with the same educational level and different cultural backgrounds (intra-education inter-culture comparisons). Several studies have demonstrated a strong association between educational level and performance on common non-verbal neuropsychological tests. When neuropsychological test performance in different cultural groups is compared, significant differences are evident. Performance on non-verbal tests such as copying figures, drawing maps or listening to tones can be significantly influenced by the individual's culture. Arguments against the use of some current neuropsychological non-verbal instruments, procedures, and norms in the assessment of diverse educational and cultural groups are discussed and possible solutions to this problem are presented.     

Verbal, perceptual and intellectual factors associated with reading achievement in adolescents with cerebral palsy

31 adolescents with cerebral palsy were administered measures of verbal production, speech perception, nonverbal auditory perception, visuospatial perception and verbal intelligence as well as measures of reading recognition and reading comprehension. Nonverbal auditory perception and verbal intelligence were most highly correlated with both reading measures despite the fact that most subjects were most severely impaired in visuospatial perception.     

Neuropsychological sequelae of stroke as a function of handedness.

The preservation of visuospatial ability relative to verbal ability following right middle cerebral artery stroke was assessed in 19 left- and 19 right-handed male patients who were group-matched on the basis of age, education, and time elapsed since stroke. Analysis of covariance (covarying education) indicated that the left- and right-handed groups were significantly different with regard to the discrepancy between Verbal IQ and Performance IQ, with the left-handed patients showing a smaller difference than the right-handers. These results provide further evidence that sinistrality may be associated with less hemispheric specialization.