Abstract: This study examined the dynamics of cognitive abilities and academic achievement from childhood to early adulthood. Predictions about time-dependent "coupling" relations between cognition and achievement based on R. B. Cattell's (1971, 1987) investment hypothesis were evaluated using linear dynamic models applied to longitudinal data (N=672). Contrary to Cattell's hypothesis, a first set of findings indicated that fluid and crystallized abilities, as defined by the Woodcock-Johnson Psycho- Educational Battery-Revised (WJ-R; R. W. Woodcock & M. B. Johnson, 1989-1990), were not dynamically coupled with each other over time. A second set of findings provided support for the original predictions and indicated that fluid ability was a leading indicator of changes in achievement measures (i.e., quantitative ability and general academic knowledge). The findings of this study suggest that the dynamics of cognitive abilities and academic achievement follow a more complex pattern than that specified by Cattell's investment hypothesis.

Abstract:  Longitudinal multivariate mixed models were used to examine the correlates of change between memory and processing speed and the contribution of age and retest to such change correlates. Various age- and occasion-mixed models were fitted to 2 longitudinal data sets of adult individuals (N >1,200). For both data sets, the results indicated that the correlation between the age slopes of memory and processing speed decreased when retest effects were included in the model. If retest effects existed in the data but were not modeled, the correlation between the age slopes was positively biased. The authors suggest that although the changes in memory and processing speed may be correlated over time, age alone does not capture such a covariation.

The primary aim of the present study was to examine longitudinal models to determine the function that best describes developmental change in processing speed during childhood and adolescence. In one sample, children and adolescents (N 5503) were tested twice over an average interval of 2 years on two psychometric measures of processing speed: Visual Matching and Cross Out. In another sample, children and adolescents (N 5 277) were tested four times, every 6 months, on Cross Out. Age-related changes in performance on both tasks were examined using six longitudinal models representing different hypotheses of growth. Linear, hyperbolic, inverse regression, and transition models yielded relatively poor fit to the data; the fit of the exponential and quadratic models was substantially better. The heuristic value of these latter models is discussed.

Abstract: The present study evaluated Reber's (1992) claim that compared to explicit learning (EL), implicit learning (IL) will be less affected by development. Sixty subjects, 20 in each of 3 age groups (2nd-  grade, 6th-  grade, and college), were measured on explicit and implicit tasks. The Analysis- Synthesis subtest of the Woodcock-Johnson Psycho- Educational Battery-Revised (1989) was used to measure EL. A modified version of the Serial Reaction Time task developed by Nissen and Bullemer (1987) was used to measure IL. Results showed that while performance on the explicit task increased with grade, performance on the implicit task, as predicted, showed no significant differences across different grades. These results support Reber's claim of the relative age- independence of IL. Furthermore, subjects' performances on EL and IL tasks were uncorrelated, suggesting that EL and IL abilities may reflect different cognitive systems. These findings provide indirect support for Reber's theory that implicit and explicit cognitive systems can be differentiated by the period of evolution in which they are thought to have emerged.

Abstract:  Objective: To investigate the 3-year course of learning disorders (LDs) and academic achievement in a sample of students with psychiatric disorders who were newly classified by the special education category of behavioral disorder (BD). Method: The occurrence of four definitions for LD (both discrepancy and low achievement) based on the WISC-R and the Woodcock-Johnson Psychoeducational Battery was followed in 81 students with BD from the time of their enrollment in BD classes to their first reevaluation after 3 years. Odds ratios (ORs) were used to measure stability of LDs in these students. Results: The prevalence of any LD was 64.2% at baseline and 61.7% at follow-up. Most of the 10 possible LD categories showed significant ORs, and the average OR was 21.9. At follow- up after 3 years, students both with and without LD at baseline had approximately the same achievement standard scores in reading and mathematics, but a significantly lower score for written language. Standard scores for the students without LD consistently were significantly higher than the scores for students with comorbid LD. Conclusion: LDs in this unique sample of students with psychiatric disorders remained common and generally stable over the first 3 years.

Abstract.  Test-retest data can reflect systematic changes over varying intervals of time in a "time- lag" design. This article shows how latent growth models with planned incomplete data can be used to separate psychometric components of developmental interest, including internal consistency reliability, test-practice effects, factor stability, factor growth, and state fluctuation. Practical analyses are proposed using a structural equation model for longitudinal data on multiple groups with different test-retest intervals. This approach is illustrated using 2 sets of data collected from students measured on the Woodcock- Johnson-- Revised Memory and Reading scales. The results show how alternative time-lag models can be fitted and interpreted with univariate, bivariate, and multivariate data. Benefits, limitations, and extensions of this structural time-lag approach are discussed.

Abstract:  Latent growth curve techniques and longitudinal data are used to examine predictions from the theory of fluid and crystallized intelligence (Gf-Gc theory; J. L. Horn & R. B. Cattell, 1966, 1967). The data examined are from a sample (N = 1,200) measured on the Woodcock- Johnson Psycho-Educational Battery—Revised (WJ–R). The longitudinal structural equation models used are based on latent growth models of age using two- occasion “accelerated”data (e.g., J. J. McArdle & R. Q. Bell, 2000; J. J. McArdle & R. W. Woodcock, 1997). Nonlinear mixed-effects growth models based on a dual exponential rate yield a reasonable fit to all life span cognitive data. These results suggest that most broad cognitive functions fit a generalized curve that rises and falls. Novel multilevel models directly comparing growth curves show that broad fluid reasoning (Gf ) and acculturated crystallized knowledge (Gc) have different growth patterns. In all comparisons, any model of cognitive age changes with only a single g factor yields an overly simplistic view of growth and change over age.

Abstract: Notes that while Head Start has decreased special education placement, there has been little systematic data until recently on identification of children in disability categories following preschool. Two cohorts of 6,162 children (aged 3-5 yrs) were followed through 3rd grade. The measures used were Peabody Picture Vocabulary Test-Revised, Woodcock-Johnson Psycho- Educational Battery-Revised, and Social Skills Rating System. Approximately half of these children were provided transition assistance from kindergarten through 3rd grade. This included school transition and curricular modifications, parent involvement activities, health screening or referrals, and family social services. They were compared to a similar group of Head Start children who did not receive such services beyond the Head Start experience. Special education eligibility was determined from school records in the spring of third grade. Only 0.89% of children in the transition group were identified in the mental retardation category compared to 1.26% in the non-transition group. In the category of emotional disturbance, these same figures were 1.21% and 1.65% respectively. Both differences were statistically significant, but an opposite effect was found in the category of speech or language impairment.

Abstract.  We examined models of individual change and correlates of change in the growth of reading skills in a sample of 40 children from kindergarten through third grade. A broad range of correlates was examined and included family literacy, oral language, emergent reading, intelligence, spelling, and demographic variables. Individual growth curve analysis was used to model change in Letter Word Identi.cation (LWID), Word Attack (WA), and Passage Comprehension (PC) subtests of the Woodcock–Johnson Psychoeducational Battery – Revised. Third grade LWID was predicted uniquely by family literacy, phonological awareness, and emergent reading skills. Growth in LWID was predicted uniquely by emergent reading skills. Phonological awareness, spelling, and emergent reading were unique predictors of third grade WA, whereas family literacy and emergent reading skills uniquely predicted third grade PC. The general oral language factor de.ned by semantic and syntactic variables did not contribute signifcant unique variance in any of the models. Thus, the pattern of results extends the model of emergent-   to- conventional literacy proposed by Whitehurst and Lonigan (1998) to third grade and suggests that early contextual understandings necessary for competent reading (family literacy and emergent reading) become more in.uential as reading skills develop.

Abstract:  Study 1 retrospectively analyzed neuropsychological and psychoeducational tests given to N = 220 first graders, with follow-up assessments in third and eighth grade. Four predictor constructs were derived: (1) Phonemic Awareness, (2) Picture Vocabulary, (3) Rapid Naming, and (4) Single Word Reading. Together, these accounted for 88%, 76%, 69%, and 69% of the variance, respectively, in first, third, and eighth grade Woodcock Johnson Broad Reading and eighth grade Gates-MacGinitie. When Single Word Reading was excluded from the predictors, the remaining predictors still accounted for 71%, 65%, 61%, and 65% of variance in the respective outcomes. Secondary analyses of risk of low outcome showed sensitivities/specificities of 93.0/91.0, and 86.4/84.9, respectively, for predicting which students would be in the bottom 15% and 30% of actual first grade WJBR. Sensitivities/specificities were 84.8/83.3 and 80.2/81.3, respectively, for predicting the bottom 15% and 30% of actual third grade WJBR outcomes; eighth grade outcomes had sensitivities/specificities of 80.0/80.0 and 85.7/83.1, respectively, for the bottom 15% and 30% of actual eighth grade WJBR scores. Study 2 cross- validated the concurrent predictive validities in an N = 500 geographically diverse sample of late kindergartners through third graders, whose ethnic and racial composition closely approximated the national early elementary school population. New tests of the same four predictor domains were used, together taking only 15 minutes to administer by teachers; the new Woodcock-Johnson III Broad Reading standard score was the concurrent criterion, whose testers were blind to the predictor results. This cross-validation showed 86% of the variance accounted for, using the same regression weights as used in Study 1. With these weights, sensitivity/specificity values for the 15% and 30% thresholds were, respectively, 91.3/88.0 and 94.1/89.1. These validities and accuracies are stronger than others reported for similar intervals in the literature.