On belief-desire reasoning tasks, children first pass tasks involving true belief before those involving false belief, and tasks involving positive desire before those involving negative desire. The current study examined belief-desire reasoning in participants old enough to pass all such tasks. Eighty-three 6- to 11-year-olds and 20 adult…

Five experiments tested hypothesis that the A-not-B error results from general processes that make goal-directed actions to remembered locations. Findings showed that 2-year-olds' performance on the A trial was accurate. When the object was hidden at Location B, searches after 10-second delay were biased in the direction of Location A. This bias…

Three experiments in which photo or video presentations could guide one's search for a hidden object showed that under certain circumstances even 24-month-olds displayed representational insight. The first two experiments replicated earlier findings of chance performance across 4 trials, with 24-month-olds performing above chance in 3 of 4…

Tested predictions of dynamic field theory in study of 3-year-olds' location memory errors in task with homogeneous task space. Found that young children's spatial memory responses are affected by delay- and experience-dependent processes as well as the geometric structure of the task space. Both dynamic field theory and category adjustment models…

Eight- to 12-month-olds might make A-not-B errors, knowing the object is in B but searching at A because of ancillary (attention, inhibitory, or motor memory) deficits, or they might genuinely believe the object is in A (conceptual deficit). This study examined how diligently infants searched for a hidden object they never found. An object was…

Strategies young children used to correct errors in nesting seriated cups changed substantially with age, becoming increasingly more flexible and involving more extensive restructuring of the relationships among the cups. The same trend toward increasing flexibility of thought and action also appeared in procedures children used to combine the…

Examined in 2 studies the ability of 2- and 3-year-olds to learn to use tools via imitation. Found that when shown a correct solution to a tool-using task, all children managed at least a partial solution. When shown an incorrect followed by a correct solution, 2-year-olds produced a partial solution and most 3-year-olds produced a full solution.…

Examined word retrieval in 14- to 24-month-olds. Found that children with limited productive vocabularies were less likely to produce labels of hidden objects than children with larger vocabularies, even though all could name them and did well when asked to find them. Pictorial cues facilitated word retrieval. Naming errors peaked among children…

Two experiments examined the communicative bases of preschoolers' object appearance-reality (AR) errors. Found that AR performance correlated positively with performance on a control test with the same discourse structure but nondeceptive stimuli, and on a naming test. Overall findings indicated that the discourse structure of AR tests elicits a…

Meta-analysis of the A-not-B error was conducted, using logistic regression, on studies conducted before September 1997. Results replicated earlier findings, with exception that the number of trials at the A location was a significant predictor, and the number of locations was a significant predictor of the proportion of infants who searched…

Three studies investigated preschoolers' reasoning about ability. Findings suggested sensitivity to mental state information when judging another child's ability, and they perceived positive correlations between effort and academic success, and "niceness" and high academic ability. Comparisons with 9- to 10-year-olds suggest that…

Two experiments tested claim that transparency of Korean fraction names promotes fraction concepts. Findings indicated that U.S. and Korean first- and second-graders erred similarly on a fraction-identification task, by treating fractions as whole numbers. Korean children performed at chance when whole-number representation was included but…

Presents a stochastic model for distinguishing mental arithmetic errors according to causes of failure. A series of experiments (1) studied questions of goodness of fit and model validity among four and five year olds and (2) used the model to measure the relative contributions of developmental improvements in short-term memory and arithmetical…