Unifying representations and responses: perseverative biases arise from a single behavioral system

Visual working memory in early development: a developmental cognitive neuroscience perspective

In this article, we review the literature on the development of visual working memory (VWM). We focus on two major periods of development, infancy and early childhood. First, we discuss the innovative methods that have been devised to understand how the development of selective attention and perception provide the foundation of VWM abilities. We detail the behavioral and neural data associated with the development of VWM during infancy. Next, we discuss various signatures of development in VWM during early childhood in the context of spatial and featural memory processes. We focus on the developmental transition to more adult-like VWM properties. Finally, we discuss computational frameworks that have explained the complex patterns of behavior observed in VWM tasks from infancy to adulthood and attempt to explain links between measures of infant VWM and childhood VWM.

Applications of Dynamic Systems Theory to Cognition and Development: New Frontiers

A central goal in developmental science is to explain the emergence of new behavioral forms. Researchers consider potential sources of behavioral change depending partly on their theoretical perspective. This chapter reviews one perspective, dynamic systems theory, which emphasizes the interactions among multiple components to drive behavior and developmental change. To illustrate the central concepts of dynamic systems theory, we describe empirical and computational studies from a range of domains, including motor development, the Piagetian A-not-B task, infant visual recognition, visual working memory capacity, and language learning. We conclude by advocating for a broader application of dynamic systems approaches to understanding cognitive and behavioral development, laying out the remaining barriers we see and suggested ways to overcome them.

Discrete and continuous stimulus control in the A-not-B sandbox task

In behavior-analytic studies of generalization, stimulus control appears to be discrete rather than continuous: after two behavior patterns R1 and R2 are trained in the presence of stimuli A and B, respectively, tests of intermediate stimuli evoke R1 and R2 in varying proportions rather than an actual mix of R1 and R2. By contrast, theories and data from developmental psychology suggest that spatial searches in the A-not-B sandbox task may be continuous: after burying an object at position A and then at position B, children may search the sand surface at positions that are actually intermediate between A and B. The published evidence so far has been ambiguous, however, because researchers typically report group means rather than response distributions, and group means intermediate between A and B might be statistical artefacts of averaging across subjects. Here we report two A-not-B sandbox studies designed to address this issue. In Experiment 1, which employed a purely motor A-not-B procedure, stimulus control was found to be continuous. In Experiment 2, which used a purely observational A-not-B procedure, stimulus control was basically discrete but also exhibited continuous aspects. These findings are discussed in relation to cognitive and behavior-analytic approaches to stimulus control.

The effect of delayed responding on Stroop-like task performance among preschoolers

Forty-four preschoolers completed 2 conditions of a Stroop-like procedure (e.g., saying "boat" for car and "car" for boat) that differed in whether a 3-s delay was imposed before responding. The test card was visible during the delay period for half of the children and occluded for the other children. Preschoolers' interference control was significantly improved in the delay condition. There was no difference between the two delay variants (test card visible or occluded). Children were more prone to interference as testing progressed regardless of whether the delay was present. These results suggest that delays effectively reduce interference by reducing the potency of the competing response during test trials, although memory demands may moderate the effectiveness of delays.

When seeing is knowing: the role of visual cues in the dissociation between children's rule knowledge and rule use

The Dimensional Change Card Sort (DCCS) task requires children to switch from sorting cards based on shape or color to sorting based on the other dimension. Typically, 3-year-olds perseverate, whereas 4-year-olds flexibly sort by different dimensions. Zelazo and colleagues (1996, Cognitive Development, 11, 37-63) asked children questions about the postswitch rules and found an apparent dissociation between rule knowledge and rule use, namely that 3-year-olds demonstrate accurate knowledge of the postswitch rules despite sorting cards incorrectly. Here, we show that children's success with these questions is grounded in their use of available visual cues; children who fail sorting use the target cards to correctly answer questions, and when the cards are unavailable they guess. This suggests that there might not be a dissociation between children's rule knowledge and rule use in the DCCS.

Toddlers benefit from labeling on an executive function search task

Although labeling improves executive function (EF) performance in children older than 3years, the results from studies with younger children have been equivocal. In the current study, we assessed performance in a computerized multistep multilocation search task with older 2-year-olds. The correct search location was either (a) not marked by a familiar picture or 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 the fewest errors when they generated the label for the hiding location. These findings support the hierarchical competing systems model, which postulates that improved performance can be explained by more powerful representations that guide search behavior.

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.

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.

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.

It Is Not Just About Location: Infants Perseverate to Container Shape During Object Search

In searching for a toy hidden at a new location, infants will err by searching at the previously correct location. This study investigated the possibility that 8.5-month-old infants would perseverate on the basis of other visual features by which covers could be individuated. Infants saw a toy hidden under 1 of 2 distinctly shaped covers. Following successful retrievals from the Shape A cover, infants saw the toy hidden under the Shape B cover. On this B trial, the covers were at locations that had not been baited on the preceding trials, precluding location perseveration. The infants erred by choosing the unbaited Shape A cover more often than control infants presented with 1 type of cover throughout. The findings suggest that infants perseverate to cover shape and are form biases biased toward cover shape even when location information is sufficient to support retrieval.

Postural change effects on infants' AB task performance: visual, postural, or spatial?

Smith and colleagues (Smith, L. B., Thelen, E., Titzer, R., & McLin, D. (1999). Knowing in the context of acting: The task dynamics of the A-not-B error. Psychological Review, 106, 235-260) demonstrated that 10-month-olds succeed on a Piagetian AB search task if they are moved from a sitting position to a standing position between A and B trials. These authors explained this result by suggesting that because the reach must be executed by different muscle forces from the standing position, an appropriate reach to B is programmed without the memory of the previous reach interfering with the current reach. In the main study reported here, the influences of postural and spatial factors are separated by adding a condition in which the table containing the hiding wells is moved up at the same time as the infant is shifted to standing, thereby allowing a postural change without a change in the spatial relations between the hand and hiding locations. Results showed that in both a standard control condition and the sitting-to-standing condition in which the table also moved up, performance was poor. Only in the sitting-to-standing condition in which the spatial relation between the hand and apparatus was altered were infants successful. These outcomes demonstrate that perseveration effects are likely to occur at the level of reach planning rather than at the level of execution, thereby narrowing the gap between explanations of improvements in AB performance with age that emphasize prefrontal maturation as opposed to improvements in reaching ability.

When Labels Hurt but Novelty Helps: Children's Perseveration and Flexibility in a Card-Sorting Task

Children often perseverate, repeating prior behaviors when inappropriate. This work tested the roles of verbal labels and stimulus novelty in such perseveration. Three-year-old children sorted cards by one rule and were then instructed to switch to a second rule. In a basic condition, cards had familiar shapes and colors and both rules were stated explicitly. In an uninformative-label condition, cards had familiar shapes and colors, but the first rule was not stated explicitly. In a novel-stimuli condition, both rules were stated explicitly but stimuli were novel on the first sorting dimension. More children switched to the second rule in the uninformative-label and novel-stimuli conditions than in the basic condition. Implications for theories of cognitive flexibility are discussed.

Toward a formal theory of flexible spatial behavior: Geometric category biases generalize across pointing and verbal response types

Three experiments tested whether geometric biases--biases away from perceived reference axes--reported in spatial recall tasks with pointing responses generalized to a recognition task that required a verbal response. Seven-year-olds and adults remembered the location of a dot within a rectangle and then either reproduced its location or verbally selected a matching choice dot from a set of colored options. Results demonstrated that geometric biases generalized to verbal responses; however, the spatial span of the choice set influenced performance as well. These data suggest that the same spatial memory process gives rise to both response types in this task. Simulations of a dynamic field model buttress this claim. More generally, these results challenge accounts that posit separate spatial systems for motor and verbal responses.