Toddlers' representations of space: the role of viewer perspective

In the present study, we examined how people code object location when an object is hidden in an enclosed space. On object location tasks involving disorientation, viewers must code the location of an object in relation to the spatial environment because they cannot directly track their changing relation to the object. Recently, we showed that viewers also code their perspective relative to the entire space (inside vs. outside) in such tasks. To determine whether viewers code perspective whenever they must locate an object, we examined young children's performance on a task in which coding perspective would be difficult. Our task involved both disorientation and translation (i.e., movement from inside to outside the space or vice versa). When translation preceded disorientation, performance was comparable to performance on tasks with no translation. However, when disorientation preceded translation, performance was at chance. The implications of these findings for location coding are discussed.     

Location representation in enclosed spaces: What types of information afford young children an advantage?

It has been suggested that young children can only reorient, locating a target object, when the geometry of an enclosed space provides distinctive shape information [e.g., Hermer, L., & Spelke, E. (1994). A geometric process for spatial reorientation in young children. Nature, 370, 57-59]. Recently, however, young children were shown to specify location in a square-shaped space, where geometry is uninformative, so long as scale-like information was available on the walls of the space [Huttenlocher, J., & Lourenco, S. F. (2007a). Coding location in enclosed spaces: Is geometry the principle? Developmental Science, 10, 741-746]. Here we build on this work by examining more closely what types of cues afford 18- to 24-month-olds an advantage in locating a target object following disorientation. Their performance was assessed when linear scale-like information was presented either in isolation or in composite form. It was found that, even in isolation, young children searched at the appropriate locations, with added benefit when presented as a composite. We suggest that linear scale-like dimensions, especially when available in composite form, play a critical role in supporting location representation in young children.     

Early development of scaling ability

The map is a small-scaled version of the space it represents. It has been argued that children have difficulty interpreting maps because they do not understand scale relations. Recent research has shown that even preschoolers can solve problems that involve scaling in one dimension. This study examined whether early scaling ability extends to tasks involving two-dimensional maps and referent spaces of different sizes. Results showed that about 60% of the 4-year-olds and 90% of the 5-year-olds tested used distance information presented on a map to locate an object in a two-dimensional spatial layout. Children had more difficulties in solving mapping tasks with a larger referent space. This decrease in accuracy as a function of space size on the mapping task was greater than would have been expected on the basis of performance on a parallel nonmapping task. The results are discussed in terms of their implications for the mechanisms underlying early scaling ability.     

Object boundaries influence toddlers' performance in a search task

Previous research has shown that young children have difficulty searching for a hidden object whose location depends on the position of a partly visible physical barrier. Across four experiments, we tested whether children's search errors are affected by two variables that influence adults' object-directed attention: object boundaries and proximity relations. Toddlers searched for a car that rolled down a ramp behind an occluding panel and stopped on contact with a barrier. The car's location on each trial depended on the placement of the barrier behind one of two doors in the panel. In Experiment 1, when a part of the car (a pompom on an antenna) was visible at the same distance from the object as the barrier wall in past research, search performance was above chance but below ceiling. In Experiments 2 and 3, when the visible part was close to the hidden body of the car and could be seen through one of two windows in the doors of the occluding panel, performance was near ceiling. In Experiment 4, when only the barrier was visible through one of the same windows, performance was at chance. Toddlers' search for a hidden object therefore is affected by the proximity of a visible part of the object, though not by the proximity of a separate visible landmark. These findings suggest a parallel between the object representations of young children and those of adults, whose attention is directed to objects and spreads in a gradient-like fashion within an object.     

A constructivist connectionist model of transitions on false-belief tasks

How do children come to understand that others have mental representations, e.g., of an object’s location? Preschoolers go through two transitions on verbal false-belief tasks, in which they have to predict where an agent will search for an object that was moved in her absence. First, while three-and-a-half-year-olds usually fail at approach tasks, in which the agent wants to find the object, children just under four succeed. Second, only after four do children succeed at tasks in which the agent wants to avoid the object. We present a constructivist connectionist model that autonomously reproduces the two transitions and suggests that the transitions are due to increases in general processing abilities enabling children to (1) overcome a default true-belief attribution by distinguishing false- from true-belief situations, and to (2) predict search in avoidance situations, where there is often more than one correct, empty search location. Constructivist connectionist models are rigorous, flexible and powerful tools that can be analyzed before and after transitions to uncover novel and emergent mechanisms of cognitive development.     

Effects of aging and task difficulty on divided attention performance

We report two experiments that compare the performance of young and older adults on perceptual-motor tasks involving division of attention. Previous studies have shown older people to be especially penalized by divided attention situations, but the generality of this finding was recently challenged by Somberg and Salthouse (1982). The present study was conducted to investigate the possibility that age differences in dual-task performance are amplified by an increase in the difficulty of the constituent tasks, where difficulty was manipulated by varying the central, cognitive nature of the tasks (Experiment 1) or the degree of choice involved (Experiment 2). With the present tasks, strong evidence was found for an age-related decrement in divided attention performance. Contrary to our original expectations, however, it does not seem that division of attention presents some especial difficulty to older people. Rather, division of attention is one of several equivalent ways to increase overall task complexity. In turn, age differences are exaggerated as tasks are made more complex.     

Imitation and representational development in young children with Down syndrome

Competence in object search and pretend play are argued to reflect young children's representational abilities and appear delayed in children with Down syndrome relative to social and imitative skills. This paper explores the effects on object search and play of this social strength in children with Down syndrome. Three experiments compared performance on traditional tasks with modified tasks designed to assess the role of imitation in object search and pretend play. Children with Down syndrome, relative to typically‐developing children, were able and willing to imitate hiding actions when no object was hidden (Experiment 1). When imitation was prevented in object search, children with Down syndrome searched less effectively than typically‐developing children (Experiment 2). In play, children with Down syndrome expressed more willingness to imitate a counter‐functional action, modelled by the experimenter, despite apparent competence in spontaneous functional play (Experiment 3). These findings indicate that object search and play behaviours of children with Down syndrome rely more heavily on imitation than is the case for typically‐developing children. The implications for the development of children with Down syndrome and models of representational development are discussed.     

Two spatial memories are not better than one: evidence of exclusivity in memory for object location

This paper studies the dynamics of attempting to access two spatial memories simultaneously and its implications for the accuracy of recall. Experiment 1 demonstrates in a range of conditions that two cues pointing to different experiences of the same object location produce little or no higher recall than that observed with a single cue. Experiment 2 confirms this finding in a within-subject design where both cues have previously elicited recall. Experiment 3 shows that these findings are only consistent with a model in which two representations of the same object location are mutually exclusive at both encoding and retrieval, and inconsistent with models that assume information from both representations is available. We propose that these representations quantify directionally specific judgments of location relative to specific anchor points in the stimulus; a format that precludes the parallel processing of like representations. Finally, we consider the apparent paradox of how such representations might contribute to the acquisition of spatial knowledge from multiple experiences of the same stimuli.     

How do young children’s spatio-symbolic skills change over short time scales?

Three experiments were designed to examine how experience affects young children's spatio-symbolic skills over short time scales. Spatio-symbolic reasoning refers to the ability to interpret and use spatial relations, such as those encountered on a map, to solve symbolic tasks. We designed three tasks in which the featural and spatial correspondences between a map and its referent (a model) were systematically manipulated using a map-model paradigm. We explored how 2.5- to 5-year-olds learn to map spatial arrays when both identical and unique correspondences coexist (Experiment 1), when featural cues are absent (Experiment 2), and when object and location similarities are contradictory, thereby making both featural and spatial mapping strategies distinct (Experiment 3). Although younger children have a stronger tendency to focus on object (or featural) cues, even 2.5-year-olds can appreciate a symbol beyond the level of object similarity. With age, children are increasingly capable of learning to use spatio-relational mapping and of discovering a spatio-symbolic mapping strategy to solve more challenging map use tasks over short time scales.     

Effects of repeated retrieval on long-term retention in a nonverbal learning task in younger children

Many studies have shown the benefits for long term retention of repeated retrieval during learning in verbal tasks, but few have shown its effectiveness using nonverbal materials. The aim of this study was to examine whether the retention benefits of repeated retrieval extend to preschool children performing a spatial location memory task. In this task, the children first studied where eight small toys were located in a partitioned box. Then, in the repeated retrieval condition, the children were asked to put each one of the toys in its place by themselves three times successively with feedback, whereas in the repeated study condition, they were asked to put each toy in its place with the experimenter showing them the correct location. Half of the children were then immediately tested and the remaining half tested after one day. The results showed that the 5 and 6 year old children in the retrieval condition retained location memory for the toys longer than those in the study condition in a memory task involving spatial content and enactment components. These findings have deep theoretical implications for the critical role of retrieval effort in long-term retention, and highlight the efficacy of repeated retrieval for different developmental ages and tasks.     

Hippocampus is required for paired associate memory with neither delay nor trial uniqueness

Cued retrieval of memory is typically examined with delay when testing hippocampal functions, as in delayed matching-to-sample tasks. Equally emphasized in the literature, on the other hand, is the hippocampal involvement in making arbitrary associations. Paired associate memory tasks are widely used for examining this function. However, the two variables (i.e., delay and paired association) were often mixed in paired associate tasks, and this makes it difficult to localize the cognitive source of deficits with hippocampal perturbation. Specifically, a few studies have recently shown that rats can learn arbitrary paired associations between certain locations and nonspatial items (e.g., object or flavor) and later can retrieve the paired location when cued by the item remotely. Such tasks involve both (1) delay between sampling the cue and retrieving the target location and (2) arbitrary association between the cueing object and its paired location. Here, we tested whether delay was necessary in a cued paired associate task by using a task in which no delay existed between object cueing and the choice of its paired associate. Moreover, fixed associative relationships between the cueing objects and their paired locations were repeatedly used, thus involving no trial-unique association. Nevertheless, inactivations of the dorsal hippocampus with muscimol severely disrupted retrieval of paired associates, whereas the same manipulations did not affect discriminating individual objects or locations. The results powerfully demonstrate that the hippocampus is inherently required for retrieving paired associations between objects and places, and that delay and trial uniqueness of the paired associates are not necessarily required.     

Spatial congruency between stimulus presentation and response key arrangements in arithmetic fact retrieval

It is known that number and space representations are connected to one another in numerical and arithmetic abilities. Numbers are represented using the metaphor of a mental number line, oriented along horizontal and vertical space. This number line also seems to be linked to mental arithmetic, which is based partly on arithmetic fact retrieval. It seems that number representation and mental arithmetic are linked together. The present study tested the effect of spatial contextual congruency between stimulus presentation and response key arrangements in arithmetic fact retrieval, using number-matching and addition verification tasks. For both tasks in Experiment 1, a contextual congruency effect was present horizontally (i.e., horizontal presentation of stimuli and horizontal response key alignments) but not vertically (i.e., vertical presentation of stimuli but horizontal response key alignments). In Experiment 2, both tasks showed a contextual congruency effect for both spatial conditions. Experiment 1 showed that the interference and distance effects were found in the horizontal condition, probably because of the spatial congruency between stimulus presentation and response key arrangements. This spatial congruency could be related to the activation of the horizontal number line. Experiment 2 showed similar interference and distance effects for both spatial conditions, suggesting that the congruency between stimulus presentation and response alignment could facilitate the retrieval of arithmetic facts. This facilitation could be related to the activation of both horizontal and vertical number lines. The results are discussed in light of the possible role of a mental number line in arithmetic fact retrieval.     

Evidence for parallel semantic memory retrieval in dual tasks

In this dual-task study, we applied both cross-talk logic and locus-of-slack logic to test whether participants can retrieve semantic categories in Task 2 in parallel to Task 1 bottleneck processing. Whereas cross-talk logic can detect parallel memory retrieval only in conditions of categorical overlap between tasks, the locus-of-slack approach is independent of such restrictions. As was expected, using the cross-talk logic, we found clear evidence for parallel retrieval of semantic categories when there was categorical overlap between tasks (Experiment 1). Locus-of-slack-based evidence for parallel semantic retrieval was found, however, both in conditions with (Experiment 1) and in those without (Experiment 2) categorical overlap between tasks. Crucially,however, increasing the demand for resources required to switch from Task 1 to Task 2 eliminated even the locus-of-slack-based evidence for parallel memory retrieval during the psychological refractory period (Experiment 3). Together, our results suggest that parallel retrieval is not bound to conditions of categorical overlap between tasks but, instead, is contingent upon resources needed for switching between tasks (e.g., Oriet, Tombu, & Jolicoeur, 2005).     

When plausibility judgments supersede fact retrieval: The example of the odd-even effect on product verification

In the present study, we examined the conditions that favor the plausibility judgment strategy over the retrieval strategy when we verify some statements. In particular, we examined the effect of odd-even status of numbers on subjects' verification of single-digit arithmetic problems. In Experiment 1, we explored how factors such as problem difficulty and stimulus onset asynchrony (SOA) influence this effect in adults. In Experiment 2, we present evidence that this odd-even effect is also present in elementary school children, although it varies with the age of the children, the difficulty of the problems, and the SOA. We argue that the odd-even information is helpful in arithmetic verification tasks with difficult problems early in the verification processes and that the time course of these effects differs across ages. The present results are consistent with the view that the plausibility strategy is preferred over the retrieval strategy at an early stage of processing and with information that is not quickly accessible. Finally, we discuss the implications of the present experiments for understanding of single-digit arithmetic and for understanding the more general issue of how people coordinate use of multiple strategies.     

The effect of feedback on children’s metacognitive judgments: a heuristic account

In three experiments, we investigated whether the feedback effect on the accuracy of children’s metacognitive judgments results from an improvement in monitoring processes or the use of the Anchoring-and-Adjustment heuristic. Experiment 1 revealed that adding feedback increased the accuracy of young children’s (aged 4, 6, and 8 years) memory prediction. In Experiment 2, the influence of an external anchor on children’s metacognitive judgment was established. Finally, in Experiment 3, two memory tasks that differed in terms of difficulty were administered. Participants were randomly assigned to an anchoring (high/low/no anchor) and a feedback (feedback/no feedback) condition. Results demonstrated that children in the feedback condition adjusted their predictions toward the feedback, regardless of the task’s difficulty. These findings are consistent with the hypothesis that external information provided by feedback is used as an anchor for judgment. This interpretation is strengthened by the correlation found between the two scores computed to assess participants’ susceptibility to anchoring and feedback effects, which indicates that children who are more sensitive to the anchoring effect are also more sensitive to the feedback effect.     

The effect of fMRI (noise) on cognitive control

Stressful situations, the aversiveness of events, or increases in task difficulty (e.g., conflict) have repeatedly been shown to be capable of triggering attentional control adjustments. In the present study we tested whether the particularity of an fMRI testing environment (i.e., EPI noise) might result in such increases of the cognitive control exerted. We found that participants were more effective in controlling episodic retrieval of previous stimulus-response bindings (Experiment 1), in switching to a new task (Experiment 2), and shielding a current goal from distracting response tendencies (Experiment 3) if they were exposed to challenging task situations, such as 70 dB echo planar imaging noise sampled from an fMRI scanner. These findings have considerable theoretical implications in questioning the widespread assumption that people are equally devoted to easy and more challenging tasks, and methodological implications in raising the possibility that experiments carried out in fMRI scanners or under otherwise challenging conditions systematically overestimate contributions from cognitive control processes.     

Long-term memory and retrieval at ages 2, 3, 4

Two experiments are reported examining the contents and accessibility of a subset of the knowledge represented in long-term memory by very young children. In Experiment 1, children aged 2 to 4 were asked in a production task to name items commonly found in particular rooms in a house, and then to verify the appropriate locations of a set of miniature replicas of household items in a dollhouse. In Experiment 2, object context was manipulated to observe if further external context improves or changes production. Children 3 and 4 years old were asked to produce appropriate room items under one of three conditons: either presented no room objects as in the first experiment, or given room objects highly- or less-frequently associated in the first study.Very young children revealed considerable knowledge in this domain, and even at the youngest ages, core defining information was retrieved. It was equally clear, however, that young children know much more than they can produce, that there is noticeable improvement in ability to retrieve information over this age range, and that additional external object context does not necessarily facilitate retrieval from long-term memory.     

The development of automatic and controlled inhibitory retrieval processes in true and false recall

In three experiments, we investigated the role of automatic and controlled inhibitory retrieval processes in true and false memory development in children and adults. Experiment 1 incorporated a directed forgetting task to examine controlled retrieval inhibition. Experiments 2 and 3 used a part-set cue and retrieval practice task to examine automatic retrieval inhibition. In the first experiment, the forget cue had no effect on false recall for adults but reduced false recall for children. In Experiments 2 and 3, both tasks caused retrieval impairments for true and false recall, and this occurred for all age groups. Implicit inhibition, which occurs outside of our conscious control, appears early in childhood. However, because young children do not process false memories as automatically as adults, explicit inhibition can reduce false memory output.     

Retrieval-based learning: The need for guided retrieval in elementary school children

Three experiments were aimed at adapting retrieval practice techniques that are effective with college students to work with elementary school children. Children participated in their classrooms and completed activities with educational texts selected from the school curriculum. In Experiment 1, when children were asked to freely recall the texts, they recalled very little of the material (about 10%) and showed almost no improvement after rereading. In another condition that involved creating concept maps, the children produced only about 20% of the ideas on their maps, even though they viewed the texts during the entire activity. Experiments 2 and 3 explored ways to provide support during retrieval activities. In Experiment 2, children were very successful at retrieving knowledge on concept maps that were partially completed. In Experiment 3, a question map activity, where questions were displayed in a relational map format, was effective for guiding retrieval practice and improving learning relative to repeated studying. The results demonstrate the importance of examining strategies that work with college students with young children in educational settings using authentic materials. The results also highlight the need for guided retrieval practice in young children.