The development of executive function in early childhood

According to the Cognitive Complexity and Control (CCC) theory, the development of executive function can be understood in terms of age-related increases in the maximum complexity of the rules children can formulate and use when solving problems. This Monograph describes four studies (9 experiments) designed to test hypotheses derived from the CCC theory and from alternative theoretical perspectives on the development of executive function (memory accounts, inhibition accounts, and redescription accounts). Each study employed a version of the Dimensional Change Card Sort (DCCS), in which children are required first to sort cards by one pair of rules (e.g., color rules: "If red then here, if blue then there"), and then sort the same cards by another, incompatible pair of rules (e.g., shape rules). Study 1 found that although most 3- to 4-year-olds failed the standard version of this task (i.e., they perseverated on the preswitch rules during the postswitch phase), they usually performed well when they were required to use four rules (including bidimensional rules) and those rules were not in conflict (i.e., they did not require children to respond in two different ways to the same test card). These findings indicate that children's perseveration cannot be attributed in a straightforward fashion to limitations in children's memory capacity. Study 2 examined the circumstances in which children can use conflicting rules. Three experiments demonstrated effects of rule dimensionality (uni- vs. bidimensional rules) but no effects of stimulus characteristics (1 vs. 2 test cards; spatially integrated vs. separated stimuli). Taken together, these studies suggest that conflict among rules is a key determinant of difficulty, but that conflict interacts with dimensionality. Study 3 examined what types of conflict pose problems for 3- to 4-yearolds by comparing performance on standard, Partial Change, and Total Change versions of the DCCS. Results revealed effects of conflict at the level of specific rules (e.g., "If red, then there"), rather than specific stimulus configurations or dimensions per se, indicating that activation of the preswitch rules persists into the postswitch phase. Study 4 examined whether negative priming also contributes to difficulty on the DCCS. Two experiments suggested that the active selection of preswitch rules against a competing alternative results in the lasting suppression of the alternative. Taken together, the results of these studies provide the basis for a revision of the CCC theory (CCC-r) that specifies more clearly the circumstances in which children will have difficulty using rules at various levels of complexity, provides a more detailed account of how to determine the complexity of rules required in a task, takes account of both the activation and inhibition of rules as a function of experience, and highlights the importance of taking intentionality seriously in the study of executive function

A hierarchical competing systems model of the emergence and early development of executive function

The hierarchical competing systems model (HCSM) provides a framework for understanding the emergence and early development of executive function – the cognitive processes underlying the conscious control of behavior – in the context of search for hidden objects. According to this model, behavior is determined by the joint influence of a developmentally invariant habit system and a conscious representational system that becomes increasingly influential as children develop. This article describes a computational formalization of the HCSM, reviews behavioral and computational research consistent with the model, and suggests directions for future research on the development of executive function

Sequence learning in infancy: The independent contributions of conditional probability and pair frequency information

The ability to perceive sequences is fundamental to cognition. Previous studies have shown that infants can learn visual sequences as early as 2 months of age and it has been suggested that this ability is mediated by sensitivity to conditional probability information. Typically, conditional probability information has covaried with frequency information in these studies, raising the possibility that each type of information may have contributed independently to sequence learning. The current study explicitly investigated the independent contribution of each type of information. We habituated 2.5-, 4.5-, and 8.5-month-old infants to a sequence of looming visual shapes whose ordering was defined independently by specific conditional probability relations among pair elements and by the frequency of occurrence of such pairs. During test trials, we tested infants' sensitivity to each type of information and found that both types of information independently influenced sequence learning by 4.5 months of age

The A-not-B error: Results from a logistic meta-analysis

A meta-analysis of the A-not-B error was conducted using logistic regression on studies conducted before September 1997 (107 data points). An earlier meta-analysis by Wellman, Cross, and Bartsch revealed that age, delay between hiding and retrieval, and number of hiding locations were significant predictors of both the proportion of infants who searched correctly on B trials and the proportion of infants who searched perseveratively. The current analysis replicated these findings with two exceptions: (1) The number of trials at the A location was a significant predictor, and (2) the number of locations was a significant predictor of the proportion of infants who searched perseveratively, but not the proportion of infants who searched correctly. Implications of these findings are discussed and a quantitative version of a hierarchical competing-systems model of infant search is proposed

Toddlers Benefit from Labeling on an Executive Function Search Task

Although labeling improves executive function (EF) performance in children older than 3 (e.g., Kirkham, Cruess, & Diamond, 2003), the results from studies with younger children have been equivocal (e.g., Sophian & Wellman, 1983). In the present study, we assessed performance in a computerized multistep multilocation search task with older 2-year-old children. The correct search location was either: (a) not marked by a familiar picture nor given a distinct label, (b) marked by a familiar picture but not given a distinct label (c) marked by a familiar picture and labeled by the experimenter, or (d) marked by a familiar picture and labeled by the participant. The results revealed that accuracy improved across conditions such that children made fewest errors when they generated the label for the hiding location. These findings support the hierarchical competing systems model (Marcovitch & Zelazo, 2006, 2009) that postulates that improved performance can be explained by more powerful representations that guide search behavior

The effect of number of A trials on performance on the A-not-B task

The A-not-B error (Piaget, 1954), which occurs when infants search perseveratively on reversal trials in a delayed-response task, is one of the most widely studied phenomena in developmental psychology. Nonetheless, the effect of A-trial experience on the probability and magnitude of this error remains unclear. In this study, 9-month-old infants were tested at location A until they searched correctly on 1, 6, or 11 A trials. Results revealed an effect of A trials on the proportion of infants who erred on the first B trial, and on the number of errors prior to a correct search at B (i.e., the error run). These effects were asymptotic, or U-shaped, consistent with a dual-process model according to which A-trial experience increases habit strength but also provides opportunities for reflection on task structure

Introduction to special issue: “The potential contribution of computational modeling to the study of cognitive development: When, and for what topics?”

As our understanding of cognitive development becomes more sophisticated, and scientists explore how processes operating at many levels of analysis (cultural, social, cognitive, neural, and molecular) work together to yield complex cognitive skills, the need for computational approaches to the study of cognitive development is increasingly apparent

U-shaped functions: Artifact or hallmark of development?

States that the articles in this collection consider one very interesting puzzle of development: U-shaped developmental functions. At some point during development, an organism might exhibit what seems like a regression from its expected developmental trajectory and, according to continuity models of development, this is aberrant. In this special issue, apparent regressions in behavior across a wide range of developmental phenomena are discussed

Perception of audiovisual rhythm and its invariance in 4- to 10-month-old infants

This study investigated the perception of complex audiovisual rhythmic patterns in 4-, 6-, 8-, and 10-month-old human infants. In Experiment 1, we first habituated infants to an event in which an object could be seen and heard bouncing in a rhythmic fashion. We then tested them to determine if they would detect a relative temporal pattern change produced by rearranging the intrapattern intervals. Regardless of age, infants successfully detected the pattern change. In Experiment 2, we asked whether infants also can extract rhythmic pattern invariance amid tempo variations. Thus, we first habituated infants to a particular rhythmic pattern but this time varying in its tempo of presentation across trials. We then administered one test trial in which a novel rhythm was presented at a familiar tempo and another test trial in which a familiar rhythm was presented at a novel tempo. Infants detected both types of changes indicating that they perceived the invariant rhythm and that they did so despite the fact that they also detected the varying tempo. Overall, the findings demonstrate that infants between 4 and 10 months of age can perceive and discriminate complex audiovisual temporal patterns on the basis of relative temporal differences and that they also can learn the invariant nature of such patterns

The influence of number of A trials on 2-years-old’s behavior in Two A-Not-B-Type search tasks: A test of the hierarchical competing systems model

Age-appropriate modifications of the A-not-B task were used to examine 2-year-olds’ search behavior. Several theories predict that A-not-B errors will in-crease as a function of number of A trials. However, the hierarchical competing systems model (Marcovitch & Zelazo, 1999) predicts that although the ratio of perseverative to nonperseverative errors will increase, the likelihood of perseveration will be an inverted U-shaped function. In Experiment 1, children received 1, 6, or 11 A trials in a multistep multilocation search task. In Experiment 2, children received 3, 7, 11, or 15 A trials in a sandbox task. Results from Experiment 1 showed that the ratio of perseverative to nonperseverative errors increased with number of A trials, and results from both Experiments 1 and 2 indicated that the likelihood of perseverative errors was highest following a moderate number of A trials. These findings are consistent with the suggestion that search behavior provides an index of the development of conscious control