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Biomedical subjects

D C Geary

Publications and source records attributed to D C Geary.

8 recordsLinked to original sources
PubMed1992

Counting knowledge and skill in cognitive addition: a comparison of normal and mathematically disabled children.

The relationship between counting knowledge and computational skills (i.e., skill at counting to solve addition problems) was assessed for groups of first-grade normal and mathematically disabled (MD) children. Twenty-four normal and 13 MD children were administered a series of counting tasks and solved 40 computer-administered addition problems. For the addition task, problem-solving strategies were recorded on a trial-by-trial basis. Performance on the counting tasks suggested that the MD children were developmentally delayed in the understanding of essential and unessential features of counting and were relatively unskilled in the detection of certain forms of counting error. On the addition task, the MD children committed many more computational errors and tended to use developmentally immature counting procedures. The immature counting knowledge of the MD children, combined with their relatively poor skills at detecting counting errors, appeared to underlie their poor computational skills on the addition task. Suggestions for future research are presented.

Child↗
PubMed1991

Cognitive addition: strategy choice and speed-of-processing differences in young and elderly adults.

Sixty young and 60 elderly adults completed a pencil-and-paper addition test and solved 40 computer-presented simple addition problems. Strategies and problem solution times were recorded on a trial-by-trial basis and were classified in accordance with the distributions of associations model of strategy choices. The elderly group showed a performance advantage on the ability measure and for the developmental maturity of the mix of problem-solving strategies, but the young group showed an advantage for overall solution times. A componential analysis of the overall solution times for memory retrieval trials, however, showed no reliable age difference for rate of retrieving addition facts from long-term memory but did suggest that the elderly adults might have been slower than the younger adults for rate of encoding digits and verbally producing an answer. Overall results are interpreted within the context of the strategy choice model.

Adolescent↗
PubMed1991

Reliability and validity of retrospective self-reports of the age of pubertal onset using twin, sibling, and college student data.

This study presents a methodology, derived from behavioral genetic research, designed to evaluate the validity of retrospective self-report inventories. The application of this technique to college student, twin, and sibling data demonstrated the reliability and validity of a retrospective self-report questionnaire on the timing of pubertal onset. Support was provided by four main findings: (1) substantial test-retest reliability coefficients for individual items (r ranged from .73 to .97) were obtained for a sample of college students; (2) nearly all of the monozygotic twin (MZ) intraclass correlations exceeded those for dizygotic twins (DZ); (3) the magnitude of the test-retest and intraclass correlations for recall of the timing of pubertal onset followed theoretical expectations for a trait demonstrating significant genetic influence (i.e., r for the same individual tested twice greater than r for MZs greater than r for DZs greater than r for siblings); (4) the expected secular trend of a cross-generational decrease in the age of sexual maturation was demonstrated for retrospective self-reports of family members representing three different generations. Moreover, the size of the mean differences across generations mirrored those reported for nonretrospective assessments of the actual age of pubertal onset. Finally, the value of retrospective self-report surveys in psychological research is discussed, and the relative merits of these instruments as indices of individual differences in pubertal development, as opposed to indices of the actual age of sexual maturation, are emphasized.

Adolescent↗
PubMed1990

A componential analysis of an early learning deficit in mathematics.

This study was designed to assess strategy choice and information-processing differences in normal and mathematically disabled first and second grade children. Twenty-three normal and 29 learning disabled (LD) children solved 40 computer-presented simple addition problems. Strategies, and their associated solution times, used in problem solving were recorded on a trial-by-trial basis and each was classified in accordance with the distributions of associations model of strategy choices. Based on performance in a remedial education course, as indexed by achievement test scores, the LD sample was reclassified into a LD-improved group and an LD-no-change group. No substantive differences comparing the normal and LD-improved groups occurred in the distribution of strategy choices, strategy characteristics (e.g., error rates), or rate of information processing. The performance characteristics of the LD-no-change group, as compared to the two remaining groups, included frequent counting and memory retrieval errors, frequent use of an immature computational strategy, poor strategy choices, and a variable rate of information processing. These performance characteristics were discussed in terms of the strategy choice model and in terms of potential long-term memory and working memory capacity deficits. In addition, implications for remedial education in mathematics were discussed.

Achievement↗
PubMed1990

Metamemory and academic achievement: testing the validity of a group-administered metamemory battery.

This study was designed to assess the validity of a recently introduced group-administered battery of metamemory tasks for children and to concurrently assess the relationship between performance on these tasks and academic achievement for second- and fourth-grade normal and learning-disabled (LD) children. Consistent with theoretical predictions and with results from individually administered metamemory tasks, significant age-related performance differences were found for four of the battery's five subtests. However, three of these four performance differences appeared to be due to a floor effect--that is, the second graders performed at chance levels for all but one of the subtests. Nevertheless, modest zero-order correlations between academic achievement measures and scores on metamemory subtests, which did show interpretable age-related performance differences, were found, as were significant group (normal versus LD) differences for fourth graders. In all, these results provided some support for the validity and the utility of the group-administered metamemory battery, although the performance of young children must be interpreted with caution.

Achievement↗
PubMed1989

A componential model for mental addition.

A componential model capable of representing simple and complex forms of mental addition was proposed and then tested by using chronometric techniques. A sample of 23 undergraduate students responded to 800 addition problems in a true-false reaction time paradigm. The 800 problems comprised 200 problems of each of four types: two single-digit addends, one single- and one double-digit addend, two double-digit addends, and three single-digit addends. The results revealed that the columnwise product of addends, a structural variable consistent with a memory network retrieval process, was the best predictor of mental addition for each of the four types of problem. Importantly, the componential model allowed estimation of effects of several other structural variables, e.g., carrying to the next column and speed of encoding of digits. High levels of explained variance verified the power of the model to represent the reaction time data, and the stability of estimates across types of problem implied consistent component use by subjects. Implications for research on mental addition are discussed.

Adolescent↗