Children's reasoning about the causal significance of the temporal order of events

Four experiments examined children's ability to reason about the causal significance of the order in which 2 events occurred (the pressing of buttons on a mechanically operated box). In Study 1, 4-year-olds were unable to make the relevant inferences, whereas 5-year-olds were successful on one version of the task. In Study 2, 3-year-olds were successful on a simplified version of the task in which they were able to observe the events although not their consequences. Study 3 found that older children had difficulties with the original task even when provided with cues to attend to order information. However, 5-year-olds performed successfully in Study 4, in which the causally relevant event was made more salient.     

Children's judgments of numerical quantity: A new view of early quantification

Three experiments investigated the role of length, density, and number dimensions in children's numerosity judgments of linear arrays of beads. The number dimension is physically defined by a length × density rule. Judgments based, even in part, on the number dimension would show signs of a length × density rule. Experiment 1 examined numerosity judgments of large arrays. Results showed that judgments by 3- and 4-year-olds obeyed a length + density rule, providing cogent evidence for a general adding strategy in young children's judgments of quantity. The physical length × density rule emerged gradually with increasing age. Experiment 2 showed that numerosity judgments of small arrays by 3- and 4-year-olds obeyed a length × density rule, indicating response to the number dimension. This result was expected and thereby validated the linearity of the response scale at the youngest ages. Experiment 3 verified the integration rules for individual 3- and 4-year-olds. The integration rules were interpreted in terms of Piaget's stages of the development of quantification. No evidence for Piaget's initial stage was found. This leads to a new view of early quantification which grants young children the ability to integrate stimulus dimensions.     

非数量视觉特征对数量感知的影响

以往许多研究探讨了各种视觉特征对数量判断任务的影响,但得出了不一致的结论.本研究依据信号检测论原理对刺激特征影响数量判断的方式进行考察.结果发现:刺激大小、形状和分布均匀度等因素可影响数量判断的反应标准,但不会影响辨别力;刺激聚集或组块会直接对数量判断的辨别力产生影响.结果表明,不同刺激特征对数量判断的影响方式存在差异.一方面,人类具有从刺激特征中直接抽取数量信息进行认知比较的能力;另一方面,刺激点聚集或组块可以直接影响被试的数量感知.此外,我们还推测,组块是通过改变客体表征的方式来影响数量感知的.     

Visual search by children: the effect of background variation and the use of visual cues

A visual search task was used to assess developmental changes in children's selective attention to specified portions of a visual display. Seven-, nine-, and twelve-year-olds searched for a target letter in matrices of letters, each of which was centered in a form. On each matrix the forms were uniform or they varied in color, shape or both color and shape. The children searched with either no cues or with color or shape cues that could be used to restrict and speed their search. In all conditions search speed increased with age. Comparisons among conditions revealed three different age trends. With no cues children of all ages were slowed comparably by variation in background forms. With color cues all children increased their search speeds relative to no-cue speeds, suggesting selective fixation, but the 12-year-olds benefited most from the cues. With shape cues the search speed of 9- and 12-year-olds was slowed while that of 7-year-olds was either unchanged or was slowed only slightly. These different trends caution against overly general statements of changes with age in selective attention, and highlight the need to consider both particular task requirements and the processes used by subjects of different ages in tasks requiring selective attention.     

Spatial cognition: gathering strategies used by preschool children

How preschool children retrieve hidden objects was examined in two cross-sectional studies. The first was a simple task in which 1- and 3-year-olds saw two treats hidden in their living room. The newly walking infants generally sought the closer treat first, providing evidence for a least-distance spatial strategy. However, this strategy was affected by a tendency to approach the hiding place most recently baited. Three-year-old children used a least-distance strategy regardless of the order of hidings. In Experiment 2, 3- and 5-year-olds saw 12 puzzle pieces hidden in various containers equally spaced within a naturally furnished children's laboratory. Factors in addition to age were the distinctiveness of the containers and a requirement to return to the center of the array after each retrieval. Overall, children of both age groups were quite successful at this task, retrieving 11 of the pieces. However, 3-year-olds were less efficient, retrieving fewer pieces and requiring more searches. Detailed analyses of errors and patterns of choices indicated differential processes in achieving their performance. Three-year-old children showed the use of memories for events, discrimination of classes of hiding places, and efficient spatial biases. Five-year-old children were more likely to exhibit these processes concurrently.     

Preschoolers' magnitude comparisons are mediated by a preverbal analog mechanism

We report a study of 3- to 5-year-olds who performed a magnitude-comparison task. Stimuli were a series of pairs of arrays that sometimes differed in numerosity, and the children were asked to point to the more numerous array in each pair. The proportion of accurate responses was above chance for all age groups. However, error patterns were consistent with analog models of magnitude representation. Errors varied systematically with the ratio of stimulus pairs. Items with a 2:3 ratio were harder than items with a 1:2 ratio. Performance on posttests of verbal counting ability was variable, but did not predict performance on the numerical discrimination task. We argue that neither verbal counting nor nonnumerical perceptual strategies can explain these results. This study supports the hypothesis that adults and children share preverbal, analog representations of magnitude.     

A heart rate analysis of developmental change in feedback processing and rule shifting from childhood to early adulthood

Over the course of development, the ability to switch between different tasks on the basis of feedback cues increases profoundly, but the role of performance monitoring remains unclear. Heart rate indexes can provide critical information about how individuals monitor feedback cues indicating that performance should be adjusted. In this study, children of three age groups (8-10, 12-14, and 16-18 years) performed a rule change task in which sorting rules needed to be detected following positive or negative feedback. The number of perseverative errors was lower for 16- to 18-year-olds than for 8- to 10-year-olds, and 12- to 14-year-olds performed at an intermediate level. Consistent with previous findings, heart rate slowed following feedback indicating a rule change, and the magnitude of slowing was similar for all age groups. Thus, 8- to 10-year-olds are already able to analyze feedback cues. In contrast, 12- to 14-year-olds and 16- to 18-year-olds, but not 8- to 10-year-olds, showed heart rate slowing following performance errors, suggesting that with age children are increasingly able to monitor their performance online. Performance monitoring may therefore be an important contributor to set-shifting ability.     

Sensitivity to spacing changes in faces and nonface objects in preschool-aged children and adults

Sensitivity to variations in the spacing of features in faces and a class of nonface objects (i.e., frontal images of cars) was tested in 3- and 4-year-old children and adults using a delayed or simultaneous two-alternative forced choice matching-to-sample task. In the adults, detection of spacing information was robust against exemplar differences for faces but varied across exemplars for cars (Experiment 1A). The 4-year-olds performed above chance in both face and car discrimination even when differences in spacing were very small (within ±1.6 standard deviations [SDs]) and the task involved memory components (Experiment 1B), and the same was true for the 3-year-olds when tested with larger spacing changes (within ±2.5 SDs) in a task that posed no memory demands (Experiment 2). An advantage in the discrimination of faces over cars was found at 4 years of age, but only when spacing cues were made more readily available (within ±2.5 SDs). Results demonstrate that the ability to discriminate objects based on feature spacing (i.e., sensitivity to second-order information) is present at 3 years of age and becomes more pronounced for faces than cars by 4 years of age.     

Local rather than global processing of visual arrays in numerosity discrimination by pigeons (Columba livia)

A series of experiments investigated which stimulus properties pigeons use when they discriminate pairs of visual arrays that differ in numerosity. Transfer tests with novel stimuli confirmed that the birds’ choices were based on relative differences in numerosity. However, pigeons differed from other species in the non-numerical cues that affected their choices. In human and non-human primates, numerical discrimination is often influenced by continuous variables such as surface area or overall stimulus brightness. Pigeons showed little evidence of using those cues, even when summed area and brightness had been correlated with numerosity differences and reward outcome. But when array-element sizes were asymmetrically distributed across numerosities, the birds readily utilized information about item sizes as an additional discriminative cue. These novel results are discussed in relation to pigeons’ tendency to focus on local, rather than global dimensions when they process other non-numerical complex visual stimuli. The findings suggest there may be inter-specific differences in the type of perceptual information that provides the input stage for mechanisms underlying numerical processing. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Numerosity-length interference: a Stroop experiment

The existence of a common mechanism for length and numerosity processing was tested with a Stroop task. Participants compared the length or the numerosity of arrays of dots, for which the two variables were manipulated independently to create congruent, incongruent, or neutral pairs. Results showed that the spatial cues strongly interfered with the processing of numerosity, whereas the numerical cues only moderately interfered with the processing of length. These findings reflect a different mandatory processing of numerosity and length.     

The effect of different methods to construct non-symbolic stimuli in numerosity estimation and comparison

Numerosity estimation and comparison tasks are often used to measure the acuity of the approximate number system (ANS), a mechanism which allows extracting numerosity from an array of dots independently from several visual cues (e.g. area extended by the dots). This idea is supported by studies showing that numerosity can be processed while these visual cues are controlled for. Different methods to construct dot arrays while controlling their visual cues have been proposed in the past. In this paper, these methods were contrasted in an estimation and a comparison task. The way of constructing the dot arrays had little impact on estimation. In contrast, in the comparison task, participants' performance was significantly influenced by the method that was used to construct the arrays of dots, indicating better performance when the visual cues of the dot arrays (partly) co-varied with numerosity. The present study therefore shows that estimates of ANS acuity derived from comparison tasks are inconsistent and dependent on how the stimuli are constructed. This makes it difficult to compare studies which utilised different methods to construct the dot arrays in numerosity comparison tasks. In addition, these results question the currently held view of the ANS as capable of robustly extracting numerosity independently from visual cues.     

Incidental learning,attention, and curiosity in squirrel monkeys calorie deprived as infants

The long-term effects of infantile malnutrition on information processing were studied in squirrel monkeys. From 2 through 8 weeks of age, four low-calorie infants were fed reduced amounts of a high protein diet, limiting their mean body weight gain to 23% of that of four well-fed controls, with all of this gain occurring during the first 2 weeks on the low-calorie diet. Thereafter, both groups received the standard diet ad libitum. At 68 weeks of age, incidental learning was tested by introducing shape cues that were redundant to the solution of a previously learned, two-choice, color discrimination. Removal of the color cues showed that the low-calorie monkeys had learned significantly less about the shape cues than had the controls. The basis for this incidental learning failure was then examined with an embedded-figures dicrimination, to measure attentional ability, and a novel stimulus substitution task, to measure curiosity. The groups did not differ in detecting embedded figures, but the low-calorie monkeys were significantly less likely than controls to select or handle novel stimuli that had been substituted for previously learned discriminative cues. It was concluded that undernutrition in infancy may induce a long-term strategy of only learning information which leads to an immediate reward, while suppressing the acquisition of information due to intrinsic curiosity.     

Relational and Representational Aspects of Early Number Development

Two experiments examined the role of representations of numerosity in children's reasoning about relations between two quantities. In the first experiment, 3- and 4-year-old children were able to solve matching-to-sample problems on the basis of both the numerosity of a focal set (number matches) and the correspondence relation between two sets (relational matches); but in a conflict condition, the younger children used only the relational information. In the second experiment, both the 3- and the 4-year-olds showed very high levels of success in inferring numerical equivalence from commutativity relations between two pairs of sets. Children were successful even when one of the sets in each pair was covered, so that children could not directly enumerate the quantities to be compared. Both findings support the notion that relational reasoning originates independently of processes for representing numerosity.     

The role of local and distal landmarks in the development of object location memory

To locate objects in the environment, animals and humans use visual and nonvisual information. We were interested in children's ability to relocate an object on the basis of self-motion and local and distal color cues for orientation. Five- to 9-year-old children were tested on an object location memory task in which, between presentation and test, the availability of local and distal cues was manipulated. Additionally, participants' viewpoint could be changed. We used a Bayesian model selection approach to compare our hypotheses. We found that, to remain oriented in space, 5-year-olds benefit from visual information in general, 7-year-olds benefit from visual cues when a viewpoint change takes place, and 9-year-olds do not benefit from the availability of visual cues for orientation but rely on self-movement cues instead. Results are discussed in terms of the adaptive combination model (Newcombe & Huttenlocher, 2006).     

The eyes have it: Young children's discrimination of age in masked and unmasked facial photographs

The ability of preschool children to discriminate age, and their use of information from different facial areas in this task, was investigated. Most 4-year-olds were able to rank sets of seven facial photographs into age order successfully. Subsequently, they were presented with facial stimuli in which different regions of the face were masked out. Masking of the eyes produced a marked performance decrement, and masking of the nose and cheeks a slight decrement, relative to masking of either the mouth and chin, or of the hair and neck. Possible explanations of the results are discussed, together with the verbal comments of the children on the cues they were aware of using.     

Numerosity discrimination in preschool children

We used a numerical bisection procedure to examine preschool children's sensitivity to the numerical attributes of stimuli. In Experiment 1 children performed two tasks. In the Cups Task they earned coins for choosing a green cup after two drumbeats and a blue cup after eight drumbeats. In the Gloves Task they earned coins for raising a red glove on their left hand after two drumbeats and a yellow glove on their right hand after eight drumbeats. Then in each task a psychometric function was obtained by presenting intermediate numerosities and recording the percentage of trials in which children chose the "many" option. In Experiment 2 children's performance in a '2 vs. 8' discrimination was compared with their performance in a "4 vs. 16" discrimination. Results showed that the individual psychometric functions were of two types, one in which the percentage of "many" choices increased gradually with stimulus numerosity and another in which it increased abruptly, in a step-like manner. Although the average point of subjective equality was close to the geometric mean of the anchor numerosities and the average functions for "2 vs. 8" and "4 vs. 16" superimposed when plotted on a common scale (the scalar property), the individual data were highly variable both across tasks (Cups and Gloves) and numerosity ranges ('2 vs. 8' and '4 vs. 16'). It is suggested that between- and within-subjects variability in the psychometric function is related to children's verbalizations about the sample stimulus.     

The effects of task instructor status on prospective memory performance in preschoolers

The present study applied a 2 × 2 experimental design to assess prospective memory (PM) development across preschool age and to examine the effect of task instructor status (researcher vs. significant other) on PM performance in 80 preschool children. Participants were required to name pictures (ongoing task [OT]), and to remember to refrain from naming but instead give a different response to certain target cues (PM task). Although the OT was of comparable difficulty for both age groups (as indicated by no performance differences), results still indicated significantly higher PM performance in 5-year-olds than in 3-year-olds, confirming the age-related increase of PM capacities between 3 and 5 years. Furthermore, results showed a performance-enhancing effect of significant others as task instructors on both age-groups. Post-hoc analysis revealed that 3-year-olds instructed by a significant other still performed marginally worse than 5-year-olds instructed by a researcher, underlining the finding that substantial changes of PM capacities take place during early childhood.     

What Is a Conventional Object Function? The Effects of Intentionality and Consistency of Use

By preschool age, children have a sophisticated assumption about the conventional nature of various kinds of information. The present studies investigated the role of two cues in 2- and 3-year-olds' determination of what is conventional, namely the intentionality and intra-individual consistency in the use of objects. Overall, in Study 1, both 2- and 3-year-olds were more likely to say that the expected use and purpose of an object was a function intentionally and consistently demonstrated. In Study 2, 3-year-olds but not 2-year-olds generalized their expectation about the conventionality of an intentionally demonstrated function to another agent's learning of the function. These findings shed light on how children's assumption of what is conventional gets refined via children's intuitive interpretive dispositions regarding human actions.     

Using a bad tool with good intention: young children's imitation of adults' questionable choices

We present three studies exploring 2- to 4-year-olds’ imitation on witnessing a model whose questionable tool use choices suggested her untrustworthiness. In Study 1, children observed the model accidentally select a physically optimal tool for a task and then intentionally reject it for one that was functionally nonaffordant. When asked to perform the task for her, children at all ages ignored the model’s intentional cues and selected the optimal tool. Study 2 found that when the model’s nonaffordant tool choice was emphasized by claims about its design, 3-year-olds increased imitation. They also imitated, as did 2-year-olds, when the model selected a suboptimal rather than nonaffordant tool. The 4-year-olds consistently avoided imitation. Study 3 replicated these findings with new tools and participants. Additional measures indicated that knowledge about artifact design predicted children’s tendency to ignore the model. These results shed light on developmental trends in the social and cognitive functions of imitation.     

Evaluative and taxonomic encoding in children's memory

The experiments were conducted to investigate the development of evaluative and taxonomic encoding in children's memory. The task used was a modification of the Wickens short-term memory task in which subjects' recall of words is tested following a distraction task. The first experiment found that 11-year-old children, but not 8-year-old children, encoded words using the evaluative dimension of the semantic differential. In the second experiment, both 7- and 11-year-olds demonstrated the ability to encode words according to taxonomic categories. These findings were related to other recent work on the development of encoding in memory.