Infant search and object permanence: a meta-analysis of the A-not-B error

Research on Piaget's stage 4 object concept has failed to reveal a clear or consistent pattern of results. Piaget found that 8-12-month-old infants would make perserverative errors; his explanation for this phenomenon was that the infant's concept of the object was contextually dependent on his or her actions. Some studies designed to test Piaget's explanation have replicated Piaget's basic finding, yet many have found no preference for the A location or the B location or an actual preference for the B location. More recently, researchers have attempted to uncover the causes for these results concerning the A-not-B error. Again, however, different studies have yielded different results, and qualitative reviews have failed to yield a consistent explanation for the results of the individual studies. This state of affairs suggests that the phenomenon may simply be too complex to be captured by individual studies varying 1 factor at a time and by reviews based on similar qualitative considerations. Therefore, the current investigation undertook a meta-analysis, a synthesis capturing the quantitative information across the now sizable number of studies. We entered several important factors into the meta-analysis, including the effects of age, the number of A trials, the length of delay between hiding and search, the number of locations, the distances between locations, and the distinctive visual properties of the hiding arrays. Of these, the analysis consistently indicated that age, delay, and number of hiding locations strongly influence infants' search. The pattern of specific findings also yielded new information about infant search. A general characterization of the results is that, at every age, both above-chance and below-chance performance was observed. That is, at each age at least 1 combination of delay and number of locations yielded above-chance A-not-B errors or significant perseverative search. At the same time, at each age at least 1 alternative combination of delay and number of locations yielded below-chance errors and significant above-chance correct performance, that is, significantly accurate search. These 2 findings, appropriately elaborated, allow us to evaluate all extant theories of stage 4 infant search. When this is done, all these extant accounts prove to be incorrect. That is, they are incommensurate with one aspect or another of the pooled findings in the meta-analysis. Therefore, we end by proposing a new account that is consistent with the entire data set.     

The Impact of the Home Instructional Program for Preschool Youngsters (HIPPY) on School Performance in 3rd and 6th Grades

A post hoc matching design was used to compare children who participated in the Home Instructional Program for Preschool Youngsters (HIPPY) throughout Arkansas to children from the same classrooms who had no preschool experience and children who had other preschool experiences in the third and sixth grades. The program showed modest positive impact on school suspensions, grades, classroom behavior, and achievement test scores at both grade levels.     

How New Caledonian crows solve novel foraging problems and what it means for cumulative culture

New Caledonian crows make and use tools, and tool types vary over geographic landscapes. Social learning may explain the variation in tool design, but it is unknown to what degree social learning accounts for the maintenance of these designs. Indeed, little is known about the mechanisms these crows use to obtain information from others, despite the question’s importance in understanding whether tool behavior is transmitted via social, genetic, or environmental means. For social transmission to account for tool-type variation, copying must utilize a mechanism that is action specific (e.g., pushing left vs. right) as well as context specific (e.g., pushing a particular object vs. any object). To determine whether crows can copy a demonstrator’s actions as well as the contexts in which they occur, we conducted a diffusion experiment using a novel foraging task. We used a nontool task to eliminate any confounds introduced by individual differences in their prior tool experience. Two groups had demonstrators (trained in isolation on different options of a four-option task, including a two-action option) and one group did not. We found that crows socially learn about context: After observers see a demonstrator interact with the task, they are more likely to interact with the same parts of the task. In contrast, observers did not copy the demonstrator’s specific actions. Our results suggest it is unlikely that observing tool-making behavior transmits tool types. We suggest it is possible that tool types are transmitted when crows copy the physical form of the tools they encounter.     

Components of attention during infants' manipulative exploration

The purpose of the project was to investigate attention in infants as they manipulate objects. It was hypothesized that examining, in contrast to other activity, reflects focused attention and active intake of information. The first study with 7- and 12-month-olds supported the hypothesis; examining declined with increasing familiarity, while other behaviors, such as mouthing and banging, did not, and examining occurred before other behaviors temporally. The latency to examine declined significantly with age. The second and third studies investigated the effects of age and familiarity on both latency to and duration of examining. Latency again decreased with age but did not change with increasing familiarity. In contrast, duration of examining did not vary systematically with age but declined sharply with familiarity. In a fourth study, latency to examine and duration of examining were related to different measures of attention at 3 1/2 years. The combination of results suggests that the latency and duration measures reflect different aspects of attention--a short-term reaction to object novelty and a more sustained response to the object and its characteristics.     

Birth order, family configuration, and verbal achievement

Two samples of National Merit Scholarship participants test in 1962 and the entire population of almost 800,000 participants tested in 1965 were examined. Consistent effects in all 3 groups were observed with respect to both birth order and family size (1st born and those of smaller families scored higher). Control of both socioeconomic variables and maternal age, by analysis of variance as well as by analysis of covariance, failed to alter the relationships. Stepdown analyses suggested that the effects were due to a verbal component and that no differences were attributable to nonverbal factors. Mean test scores were computed for detailed sibship configurations based on birth order, family size, sibling spacing, and sibling sex.     

Cognitive deficits in reading disability and attention deficit disorder

This paper presents data from three studies (a cross-sectional study of school-referred children, a test-retest study of subtypes of reading disabilities, and a study of a large, random sample of first graders) that focus on specifying the cognitive deficits associated with reading difficulties and separating them from those associated with attentional deficits. The cognitive deficits associated with difficulty in reading were consistent across samples, developmental levels, definitions, and subtypes of reading disabilities. With IQ, age, and sex controlled for, poor readers were significantly impaired on measures of naming and phonological awareness. The effects of attentional deficits were more variable and complex but were clearly separate from the reading disability effects.