Raven's Progressive Matrices Scores Research Articles

Comparative assessment of cognitive function of asthmatic and non-asthmatic children in Ilorin, Nigeria

Background The presence of asthma in children may negatively impact their cognitive function, possibly due to intermittent hypoxia from repeated acute exacerbations, sleep deprivation, and school absenteeism. However, conflicting reports abound on cognitive performance among children with asthma. Objective To assess and compare the cognitive function of asthmatic and non-asthmatic children in Ilorin, Nigeria. Methods This cross-sectional study compared the cognitive performance scores of 66 children with asthma aged 6-17 years, and the corresponding scores of 66 healthy age- and gender-matched children without asthma. Data obtained included sociodemographic, anthropometric, and clinical details. Cognitive function was assessed with the Raven's Progressive Matrices (RPM) psychometric test. Results The male: female ratio was 1.3:1. The median RPM score of 50.0 [interquartile range (IQR) 25.0-75.0] in children with asthma was significantly higher than that of non-asthmatic children [32.5 (IQR 10.0-50.0)]; (P=0.016). A significantly higher proportion of asthmatic subjects (74.2%) were in the high grade RPM score category compared to the non-asthmatic children’s concomitant proportion (57.6%). Asthmatic subjects were twice as likely to belong to the high grade RPM score category than their non-asthmatic counterparts (OR=2.12; 95%CI 1.02 to 4.44; P=0.043). There was no significant association between RPM score grade and clinical severity of asthma in the subject population (P=0.554). Conclusion Children with asthma perform better in cognitive function assessment, using RPM test, compared to their non-asthmatic counterparts in Ilorin, Nigeria.

Circulating asymmetric dimethylarginine and cognitive decline: A 4-year follow-up study of the 1936 Aberdeen Birth Cohort.

The underlying mechanisms leading to dementia and Alzheimer's disease (AD) are unclear. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, may be associated with cognitive decline, but population-based evidence is lacking. Change in cognitive performance was assessed in participants of the Aberdeen Birth Cohort of 1936 using longitudinal Raven's progressive matrices (RPM) between 2000 and 2004. Multiple linear regression was used to estimate the association between ADMA concentrations in 2000 and change in cognitive performance after adjustment for potential confounders. A total of 93 participants had complete information on cognitive performance between 2000 and 2004. Mean plasma ADMA concentrations were approximately 0.4 μmol/L lower in those participants with stable or improved RPM scores over follow-up compared with participants whose cognitive performance worsened. In confounder-adjusted analysis, one SD (0.06 μmol/L) increase in ADMA at 63 years of age was associated with an average reduction in RPM of 1.26 points (95% CI 0.14-2.26) after 4 years. Raised plasma ADMA concentrations predicted worsening cognitive performance after approximately 4 years in this cohort of adults in late-middle age. These findings have implications for future research, including presymptomatic diagnosis or novel therapeutic targets for dementia and AD.

Variations in Raven's Progressive Matrices scores among Chinese children and adolescents

Several studies have assessed intelligence using Raven's Progressive Matrices (RPM) across the life span. However, limited research has been done on the current Chinese population. This study recruited 6970 children and adolescents (age = 8–16 years) from eastern China to investigate intelligence and its variations. The results showed that Standard Progressive Matrices (SPM) scores are correlated to Coloured Progressive Matrices (CPM) scores for 8–16 year olds (P < 0.05). The 50th percentile of both the SPM and CPM scores could be an effective indicator of the cognitive growth curve increase from ages 8 to 16 years. The CPM test, a simple version, may be applicable for children under 10 years of age, and the SPM scores could be used for the transformation of the IQ score. Girls slightly outperformed boys with two IQ points at age 13 and15 to 16 years. In addition, day students had an advantage of 1–2 SPM scores and 2–4 IQ points compared to boarding school students between the ages of 12 to 14 years. In general, our results agree with sex differences on the RPM, especially at ages 13, 15 and 16 years. Further research is needed to enhance performance on the intelligence tests.

Comprehensive Investigation of White Matter Tracts in Professional Chess Players and Relation to Expertise: Region of Interest and DMRI Connectometry.

Purpose: Expertise is the product of training. Few studies have used functional connectivity or conventional diffusometric methods to identify neural underpinnings of chess expertise. Diffusometric variables of white matter might reflect these adaptive changes, along with changes in structural connectivity, which is a sensitive measure of microstructural changes.Method: Diffusometric variables of 29 professional chess players and 29 age-sex matched controls were extracted for white matter regions based on John Hopkin's Mori white matter atlas and partially correlated against professional training time and level of chess proficiency. Diffusion MRI connectometry was implemented to identify changes in structural connectivity in professional players compared to novices.Result: Compared to novices, higher planar anisotropy (CP) was observed in inferior longitudinal fasciculus (ILF), superior longitudinal fasciculus (SLF) and cingulate gyrus, in professional chess players, which correlated with higher RPM score in this group. Higher fractional anisotropy (FA) was observed in ILF, uncinate fasciculus (UF) and hippocampus and correlated with better scores in Raven's progressive matrices (RPM) score and longer duration of chess training in professional players. Consistently, radial diffusivity in bilateral IFOF, bilateral ILF and bilateral SLF was inversely correlated with level of training in professional players. DMRI connectometry analysis identified increased connectivity in bilateral UF, bilateral IFOF, bilateral cingulum, and corpus callosum in chess player's compared to controls.Conclusion: Structural connectivity of major associational subcortical white matter fibers are increased in professional chess players. FA and CP of ILF, SLF and UF directly correlates with duration of professional training and RPM score, in professional chess players.

Prepregnancy overweight and obesity are associated with impaired child neurodevelopment.

The authors examined the relationship of prepregnancy body mass index (BMI) and gestational weight gain (GWG) with child neurodevelopment. Mother-child dyads were a subgroup (n=2,084) of the Child Health and Development Studies from the Oakland, California, area enrolled during pregnancy from 1959 to 1966 and followed at child age 9years. Linear regression was used to examine associations between prepregnancy BMI, GWG, and standardized Peabody Picture Vocabulary Test and Raven Progressive Matrices scores and to evaluate effect modification of GWG by prepregnancy BMI. Before pregnancy, 77% of women were normal weight, 8% were underweight, 11% were overweight, and 3% were obese. Associations between GWG and child outcomes did not vary by prepregnancy BMI, suggesting no evidence for interaction. In multivariable models, compared to normal prepregnancy BMI, prepregnancy overweight and obesity were associated with lower Peabody scores (b: -1.29; 95% CI [-2.6, -0.04] and b: -2.7; 95% CI [-5.0, -0.32], respectively). GWG was not associated with child Peabody score [b: -0.03 (95% CI: -0.13, 0.07)]. Maternal BMI and GWG were not associated with child Raven score (all P>0.05). Maternal prepregnancy overweight and obesity were associated with lower scores for verbal recognition in mid-childhood. These results contribute to evidence linking maternal BMI with child neurodevelopment. Future research should examine the role of higher prepregnancy BMI values and the pattern of pregnancy weight gain in child cognitive outcomes.

Neurocognitive Function of School-aged HIV-infected Children in Enugu, Nigeria.

Evidence has shown neurocognitive problems often exist among human immunodeficiency virus (HIV)-infected children. There are limited data for children in Nigeria. This was a cross-sectional study of 100 school-aged perinatally HIV-infected children seen in the paediatric HIV clinic and age/sex-matched controls from the general paediatric clinic. Neuro-cognitive functioning was assessed using the Raven's progressive matrices (RPM) that has been adapted for the Nigerian population. The mean RPM score of subjects was 22.97 ± 11.35 compared with 32.93 ± 15.71 among controls (p < 0.001). Twenty-two percent of subjects in the HIV-infected group vs. 56% of controls were in the above-average intelligence group on the RPM. Thirty-four percent had average scores, while 22% were in the below-average scoring range. Neuro-cognitive functioning of the subjects was significantly affected by immunologic staging and socio-economic status. Neurocognitive functioning of the HIV-infected children was significantly lower than those of their un-infected counterparts. Neurodevelopmental evaluation should be part of standard care in HIV-infected children in Nigerian setting.

Does WISC-IV Underestimate the Intelligence of Autistic Children?

Wechsler Intelligence Scale for Children (WISC) is widely used to estimate autistic intelligence (Joseph in The neuropsychology of autism. Oxford University Press, Oxford, 2011; Goldstein et al. in Assessment of autism spectrum disorders. Guilford Press, New York, 2008; Mottron in J Autism Dev Disord 34(1):19-27, 2004). However, previous studies suggest that while WISC-III and Raven's Progressive Matrices (RPM) provide similar estimates of non-autistic intelligence, autistic children perform significantly better on RPM (Dawson et al. in Psychol Sci 18(8):657-662, doi: 10.1111/j.1467-9280.2007.01954.x , 2007). The latest WISC version introduces substantial changes in subtests and index scores; thus, we asked whether WISC-IV still underestimates autistic intelligence. Twenty-five autistic and 22 typical children completed WISC-IV and RPM. Autistic children's RPM scores were significantly higher than their WISC-IV FSIQ, but there was no significant difference in typical children. Further, autistic children showed a distinctively uneven WISC-IV index profile, with a "peak" in the new Perceptual Reasoning Index. In spite of major changes, WISC-IV FSIQ continues to underestimate autistic intelligence.

Early-life determinants of cognitive ability in childhood and old age

BackgroundFactors early in life, even prenatally, could affect subsequent health and development of disease. Studies have consistently shown a small but significant correlation between birthweight in the normal range and childhood cognitive ability. However, only two studies have investigated whether this correlation persists into older age, showing no significant effect. The aim of this investigation was to assess whether factors early in life (birthweight, gestational age, parity, antenatal complications, neonatal complications, and social group), affect cognition in childhood and whether these effects persist. MethodsThe Aberdeen 1936 Birth Cohort (ABC1936) is a longitudinal study of cognitive ageing in a well-characterised cohort of individuals born in 1936 (n=506 of 658 alive and resident in Aberdeen, were recruited in 2000). The study is ongoing with wave 4 of testing completed in 2011 (n=216). Only wave 1 (baseline) data are presented here. In wave 1, participants underwent a battery of cognitive and physical tests at age 64–66 years. Results for Raven's Progressive Matrices (RPM), a test of non-verbal reasoning, are reported here. The test was administered by a trained research nurse and individuals had 20 min to complete as many of the multiple choice problems as possible. All 658 individuals invited to participate in ABC1936 had IQ measured with the Moray House Test when aged 11 years as part of the nationwide Scottish Mental Survey 1947. Some were born in hospital, and therefore had prospectively obtained data available for perinatal effects. Birth data were obtained for all hospital births in Aberdeen in 1936 (n=1250). Results are reported for individuals who had birth data, IQ at age 11 years, and IQ at age 64–66 years available. Associations between cognitive ability scores (at both ages) and potential predictors (sex, social group at birth, birthweight, gestational age, parity, antenatal or neonatal complications) were tested. Factors significantly associated with cognitive ability (p<0·1) were included in multivariate regression models for the prediction of childhood IQ and RPM scores. FindingsOf participants with childhood IQ available, 140 (21%) had birth data available. Of those, 108 (77%) had IQ scores at age 64–66 years. Mean IQ scores did not differ between those with birth data and those without at either age 11 years (with birth data, mean 38·3 [SD 13·8]; without birth data, mean 40·3 [14·0]; p=0·06) or age 64–66 years (with birth data, mean 34·7 [8·2]; without birth data, mean 35·8 [8·8]; p=0·21). Birthweight was not significantly correlated with childhood cognitive ability (r=0·07; p=0·39). Multivariate regression analysis showed that low perinatal social group (unskilled manual work compared with others; β=–0·23; p=0·007) and increased parity (β=–0·21; p=0·015) were associated with decreased test scores in childhood (adjusted R2=0·09). Neither birthweight (r=–0·003; p=0·77) nor perinatal social group (p=0·56) were significantly associated with RPM scores. In older age, increased childhood cognitive test scores (β=0·47; p<0·0001) and male sex (β=0·31; p<0·0001) were associated with improved performance (adjusted R2=0·35). InterpretationIn this fairly small cohort, birthweight and childhood or older age IQ were not associated. Childhood IQ was predicted by social group and parity, and was the main predictor of older age IQ. Longitudinal data from more than six decades, including prospectively recorded birth data, are rare. The reasons for differences between this cohort and others in Scotland and worldwide should be explored, and could include cohort effects, residual confounding factors, and selection bias. Early-life programming of cognitive function is not a significant determinant in this cohort. FundingThe Alzheimer's Research Trust funded data collection during wave 1 of ABC1936; RLS is funded by an NRS Career Researcher Fellowship.

Brain structural complexity and life course cognitive change

Fractal measures such as fractal dimension (FD) can quantify the structural complexity of the brain. These have been used in clinical neuroscience to investigate brain development, ageing and in studies of psychiatric and neurological disorders. Here, we examined associations between the FD of white matter and cognitive changes across the life course in the absence of detectable brain disease. The FD was calculated from segmented cerebral white matter MR images in 217 subjects aged about 68years, in whom archived intelligence scores from age 11years were available. Cognitive test scores of fluid and crystallised intelligence were obtained at the time of MR imaging. Significant differences were found (intracranial volume, brain volume, white matter volume and Raven's Progressive Matrices score) between men and women at age 68years and novel associations were found between FD and measures of cognitive change over the life course from age 11 to 68years. Those with greater FD were found to have greater than expected fluid abilities at age 68years than predicted by their childhood intelligence and less cognitive decline from age 11 to 68years. These results are consistent with other reports that FD measures of cortical structural complexity increase across the early life course during maturation of the cerebral cortex and add new data to support an association between FD and cognitive ageing.

The Level and Nature of Autistic Intelligence II: What about Asperger Syndrome?

A distinctively uneven profile of intelligence is a feature of the autistic spectrum. Within the spectrum, Asperger individuals differ from autistics in their early speech development and in being less likely to be characterized by visuospatial peaks. While different specific strengths characterize different autistic spectrum subgroups, all such peaks of ability have been interpreted as deficits: isolated, aberrant, and irreconcilable with real human intelligence. This view has recently been challenged by findings of autistic strengths in performance on Raven's Progressive Matrices (RPM), an important marker of general and fluid intelligence. We investigated whether these findings extend to Asperger syndrome, an autistic spectrum subgroup characterized by verbal peaks of ability, and whether the cognitive mechanisms underlying autistic and Asperger RPM performance differ. Thirty-two Asperger adults displayed a significant advantage on RPM over Wechsler Full-Scale and Performance scores relative to their typical controls, while in 25 Asperger children an RPM advantage was found over Wechsler Performance scores only. As previously found with autistics, Asperger children and adults achieved RPM scores at a level reflecting their Wechsler peaks of ability. Therefore, strengths in RPM performance span the autistic spectrum and imply a common mechanism advantageously applied to different facets of cognition. Autistic spectrum intelligence is atypical, but also genuine, general, and underestimated.

Variation in Raven's Progressive Matrices scores across time and place

The paper describes a cross-cultural and historical meta-analysis of Raven's Progressive Matrices. Data were analyzed of 798 samples from 45 countries ( N = 244,316), which were published between 1944 and 2003. Country-level indicators of educational permeation (which involves a broad set of interrelated educational input and output factors that are strongly related to economic development), the samples' educational age, and publication year were all independently related to performance on Raven's matrices. Our data suggest that the Flynn effect can be found in high as well as low GNP countries, although its size is moderated by education-related sample and country characteristics and seems to be smaller in developed than in emerging countries.

Differential cognitive outcomes in the Hypertensive Old People in Edinburgh study

Hypertension is associated with cognitive impairment in older adults. The Hypertensive Old People in Edinburgh (HOPE) study reported improved scores in two psychometric tests in those subjects with the greatest fall in diastolic blood pressure during a 24-week randomised, double-blind trial of captopril versus bendrofluazide in 81 elderly hypertensive people with mild cognitive impairment. Three hundred and eighty-seven of the original sample of 603 older people with and without hypertension and/or cognitive impairment from which the trial subsample was drawn were available for adequate psychometric testing 4 years later. Blood pressure was related prospectively to Raven's Progressive Matrices (RPM), a measure of fluid intelligence, but not memory differences. RPM scores were obtained at baseline, 6 weeks, 12 weeks and at the end of the randomised controlled trial. For subjects on captopril mean scores at each time point adjusted for blood pressure change were 27.6 (95% CI 25.5–29.6), 27.2 (95% CI 25.1–29.2), 28.4 (95% CI 26.6–30.3) and 28.9 (95% CI 26.9–30.9), and for bendrofluazide 27.1 (95% CI 25.1–29.0), 28.9 (95% CI 26.9–30.9), 28.9 (95% CI 27.2–30.7) and 28.7 (95% CI 26.8–30.6). There was a significant improvement in scores for those on bendrofluazide compared with captopril at week 6 ( F=8.10, p=0.006, partial η 2=0.11). There were no significant effects for either drug or blood pressure at any time point for tests of memory. Future trials of the effects of antihypertensive therapy on cognition should focus more on outcomes other than memory. Early differential effects of therapeutic agents may not be maintained.

Intelligence and Family Marital Structure: The Case of Adolescents From Monogamous and Polygamous Families Among Bedouin Arabs in Israel

The levels of intelligence among Bedouin Arab adolescents from monogamous and polygamous families living in the Negev region of Israel were examined. A shortened version of the Raven's Progressive Matrices (RPM) test (S. Elbedour, T. J. Bouchard, & Y. Hur, 1997; J. Raven, J. C. Raven, & J. H. Court, 1998) was used to assess intelligence. There were no significant test score differences between adolescents from monogamous families and adolescents from polygamous families. In addition, participants with 2 mothers tended to have lower RPM scores than those with 3 or 4 mothers, and participants with related parents tended to have lower RPM scores than participants with unrelated parents. One major finding of this study is that polygamous family marital structures tended not to have deleterious effects on the Bedouin Arab adolescents' RPM test scores.

Cognitive status in Down syndrome individuals with sleep disordered breathing deficits (SDB)

Twelve subjects with Down syndrome underwent polysomnographic studies during night sleep and performed the Mini-Mental state test and the Raven Progressive Matrices (RPM), sets A, B, and B 1. Sleep-disordered breathing (SDB) deficits were observed in Down syndrome individuals and their Mini-Mental and RPM scores were extremely low. Regression analysis of the results revealed that the number of apneas per hour was related with the results of the RPM, set A, which were also related with the orientation of Mini-Mental test, indicating that the more apneas an individual has the more difficulties he has in the kind of visuoperceptual skills, including orientation, associated with normal right hemisphere functioning, which are tested by set A of the RPM.

Homocysteine, B vitamin status, and cognitive function in the elderly

Old age is associated with reduced cognitive performance. Nutritional factors may contribute to this association. We tested associations between cognitive performance and plasma vitamin B-12, folate, and homocysteine concentrations in the elderly. We studied survivors of the Scottish Mental Surveys of 1932 (Aberdeen 1921 Birth Cohort, or ABC21) and 1947 (Aberdeen 1936 Birth Cohort, or ABC36), which surveyed childhood intelligence quotient. We measured folate, vitamin B-12, and homocysteine concentrations in fasting blood samples and cognitive performance by the Mini Mental State Examination (MMSE), National Adult Reading Test (NART), Raven's Progressive Matrices (RPM), Auditory Verbal Learning Test (AVLT), digit symbol (DS) subtest, and block design (BD) subtest. Homocysteine was higher in the ABC21 than in the ABC36 (P < 0.0001). There were positive correlations between folate and vitamin B-12 and negative correlations between homocysteine and both folate and vitamin B-12. MMSE, RPM, AVLT, DS, and BD scores were higher in the ABC36. In the ABC21, folate, vitamin B-12, and MMSE score were positively correlated and homocysteine was negatively correlated with RPM, DS, and BD scores. Folic acid was positively correlated with AVLT and DS scores. In the ABC36, folate was positively correlated with BD score. After adjustment for childhood intelligence quotient, partial correlations were strengthened between vitamin B-12 and NART score and between homocysteine and RPM score but weakened between red blood cell folate and DS score. B vitamins and homocysteine are associated with cognitive variation in old age. In the ABC21 but not the ABC36, homocysteine accounted for approximately 7-8% of the variance in cognitive performance. This may prove relevant to the design of neuroprotective studies in late life.

Models of spouse similarity: Applications to fluid ability measured in twins and their spouses

Genetic influences have consistently been reported to be the principal explanation for resemblance among relatives for intelligence, with shared environmental effects playing a much smaller role. However, crucial to understanding the nature of environmental influences are the mechanisms of assortative mating. Phenotypic assortment, albeit widely assumed or modeled in biometrical analyses, may be less important than other assortment processes, such as social homogamy. Consequently, effects of shared environment may play a greater role than prior studies have suggested. The goal of this study was to resolve environmental and genetic influences on fluid ability based on alternative models of assortment by examining the similarity of monozygotic (MZ) and dizygotic (DZ) twins and their spouses. Raven's Progressive Matrices scores were available from a population-based Swedish sample of 138 twin kinships. The effects of both social homogamy and phenotypic assortment were tested simultaneously in each of two alternate assortment models. A factor/delta path model represented social homogamy as a common factor and phenotypic assortment as a delta path, while a delta/delta path model represented both social homogamy and phenotypic assortment as delta paths. Overall, the factor/delta path model was found to be superior. Results suggested that social homogamy completely explained spouse similarity; phenotypic assortment was not significant. The results of these analyses suggest the presence of shared environmental effects among twins and their spouses, which would have been underestimated if only phenotypic modeled phenotypic assortment may have underestimated the effects of environment.

Gender-related decrease in Raven's progressive matrices scores in children prenatally exposed to polychlorinated biphenyls and related contaminants

Polychlorinated biphenyls (PCBs) and industrial mixtures that have been widely used throughout the world. PCBs have long environmental half lives and bioconcentrate, therefore contaminating soil, water, wild life, and human tissues. Typical human exposures come from environmental contamination of food supply, especially fresh water fish and meat, and occupational exposures. In certain uses, PCBs can partially oxidize and themselves become contaminated by extremely toxic compounds such as polychlorinated dibenzofurans (PCDFs). Two episodes of intoxication with heat-degraded PCBs have occurred, in Japan and Taiwan respectively. In 1979, over 2000 persons in Taiwan were intoxicated by heat-degraded PCBs that had contaminated their cooking oil. Kaneclor 500 (a Japanese PCB mixture) contained in the heating pipe was used as the heat transmitter. Leakage of the pipe introduced PCBs and heat-degraded products such as polychlorinated dibenzofurans (PCDFs) and polychlorinated quaterphenyls (PCQs) into the rice oil. Exposed victims developed chloracne, hyperpigmentation, peripheral neuropathy, and other signs and symptoms which were later called Yu-Cheng ({open_quotes}oil disease{close_quotes}) in Taiwan. These symptoms were caused not only by PCBs but by their heat degraded products, PCDFs. PCBs, PCDFs and PCDDs also can cross the placenta to affect the fetus and cause significant neurodevelopmental toxicity. Raven`s Colored Progressive Matrices (CPM)more » and Standarized Progressive Matrices (SPM) test spatial rather than verbal capabilities in children. These test are useful for determining whether prenatal exposure to PCBs/PCDFs cause differential effects on boys and girls. This paper reports results of CPM and SPM from age six to nine year in Yu-Cheng children and their matched controls. Cognative deficits up to 9 years of age were detected n children with prenatal exposure to PCBs and PCDFs, and boys were more affected than girls. 26 refs., 1 fig., 2 tabs.« less

High speed memory scanning in retarded and non-retarded adolescents.

Four groups of 13-14-year-olds, classified on the basis of Raven's Progressive Matrices scores as intellectually above average, average, below average and retarded, were subjects in a Sternberg (1966) type memory scanning task in which memory sets of two, three and four letters were used. Slope values of the memory search function did not differ between groups, whereas intercept values decreased with higher intelligence up to the average intelligence level. There was an overall inverse relation between intercept values and intelligence (r = -0.77) and similar relations obtained within the three non-retarded groups (rs greater than or equal to -0.57), but not within the retarded group (r = -0.06). Possible connections between these results and findings from inspection time studies are discussed.

Bilingualism and Metalinguistic Ability among Kond Tribals in Orissa, India

Summary Studies on cognitive consequences of bilingualism have often confounded the effects of bilingualism and culture by comparing monolinguals and bilinguals belonging to different cultures. The Kond tribal society in Orissa provides an ideal setting for an investigation, since the bilingual and monolingual Konds share a common culture. A test of metalinguistic ability and Raven's Progressive Matrices (RPM) were given to 180 bilingual and monolingual Konds of three age levels. The bilinguals, using two linguistic devices to encode their experience, were expected to have a better analytic strategy facilitating their metalinguistic development. The metalinguistic ability scores were analyzed in 2 (bilingual/monolingual) × 3 (age) ANCOVA with RPM scores as covariate to control for the effect of nonverbal intelligence. The bilinguals scored significantly better than the monolinguals. The results are interpreted as again showing the nature of the positive effect of a second language on individuals' thought processes.

Mental Speed, Response Time, and Intelligence

Recent studies have reported significant correlations between response time, varying from push-button reaction time to sentence verification time, and intelligence scores. The present study obtained correlations in the opposite direction: faster subjects in a word-judging task had lower Raven's Progressive Matrices scores. A distinction might be made between speed of mental processes and response time. Mental speed is only inferred from response time and assumes knowledge of the processes leading to response. Mental speed could conceivably be correlated with intelligence but response time needs not.