Minding the gap: a sex difference in young infants' mental rotation through thirty degrees of arc

Mental rotation (MR) is an important feature of spatial cognition invoking mental imagery of an object's appearance when viewed from a new orientation. Prior studies have revealed evidence of MR in infants, including a sex difference similar to that detected in older populations. Some of these studies used visual habituation methods whereby infants were familiarized with an object rotating through a 240° angle, followed by test trials showing either the habituation object or a mirror image object rotating through the previously unseen 120° angle. Significantly longer looking at either of these objects was taken to reflect infants' ability to recognize the habituation object even when seen from a novel viewpoint, suggesting the capacity for MR. However, these infants' responses could, in theory, be explained with reference to perceptual discrimination rather than MR, because the views of the habituation and test objects were very similar in some video frames. In the current study, we observed a diverse population of 5-month-olds (24 females, 24 males) for evidence of MR through 30° of arc. In this more challenging test, our stimuli left a 30° gap angle between critical video frames representing the habituation and test objects. Consistent with earlier reports, we found that relative to female infants, male infants looked significantly longer at the mirror image test stimulus immediately following habituation. These results add to an emerging consensus that some young infants are capable of MR, and that male and female infants on average behave differently in this type of MR task.

How babies use their hands to learn about objects: Exploration, reach-to-grasp, manipulation, and tool use

Object play is essential for infant learning, and infants spend most of their day with objects. Young infants learn about objects and their properties through multimodal exploration facilitated by caregivers. They figure out how to transport their hands to where objects are, and how to grasp objects in increasingly complex ways. Building on earlier experiences, they learn how to use their hands collaboratively to act on objects, and how to use objects to act on other objects in instrumental ways. These changes in how infants use their hands occur during the most rapid period of motor development and may have important downstream implications for other domains. Recent research findings have established the importance of effective fine motor skills for later academic skills, yet our understanding of the factors that influence the early development of hand skills is sparse at best. Latest research on reaching, grasping, object manipulation, hands collaboration, and tool use is reviewed and connections among these developments are explained from the perspective of developmental cascades. This article is categorized under: Psychology > Motor Skill and Performance Psychology > Development and Aging.

Children's generalization of novel names in comparison settings: The role of semantic distance during learning and at test

There is considerable evidence showing that, in novel noun learning and generalization tasks, comparisons of several learning stimuli lead to more taxonomically based generalizations of novel nouns than single stimulus presentations. This study investigated the role of semantic distance (close vs. far) between learning examples and between learning examples and transfer items (near vs. distant) in comparison designs. In two experiments, we investigated the case of object nouns (e.g., foods, Experiment 1) and relational nouns (e.g., is the cutter for, Experiment 2) in 4- to 6-year-old and 3- to 4-year-old children, respectively. As predicted, the comparison conditions led to better results than the no-comparison conditions. In comparison conditions, far training items and near generalization items gave the best performance. Semantic distance effects are discussed in terms of abstracted representations during learning as well as in terms of cognitive constraints on generalization. It is argued that both object nouns and relational nouns are construed in the light of the type of example used during learning (i.e., single or multiple). Depending on the distance between learning and generalization items, children build different categories and are more or less likely to accept distant referents.

Discovering category boundaries: The role of comparison in infants' novel category learning

A key question in categorization is how infants extract regularities from the exemplars they encounter. Detecting similarities and dissimilarities across items is vital in order to determine category-relevant features. Previous research found evidence that infants acquire a single category more easily with paired presentations in comparison with single presentations (Oakes & Ribar, 2005, Infancy, 7, 85; Oakes & Kovack-Lesh, 2007, Cogniție, Creier, Comportament / Cognition, Brain, Behavior, XI, 661). Here, we focus on infants' acquisition of a category contrast, that is, when they are exposed to two categories. In an eye-tracking study, we examined 10-month-old infants' ability to learn two novel visual categories when presented with one item at a time and with items in pairs. Infants were familiarized with pairs of items from the same category or with pairs of items from different categories (cross-category pairs). Using a linear model with a priori contrasts, we show that infants' learning is directly related to the opportunity for category comparison: There is no evidence of category learning in the single-item condition, improved performance when familiarized with same-category pairs, and finally robust category learning when familiarized with cross-category pairs. We conclude that comparison which involves items from different categories promotes category formation, by highlighting differences and promoting a discovery of category boundaries.

Linguistic and developmental influences on superordinate facial configuration categorization in infancy

Humans perceive emotions in terms of categories, such as "happiness," "sadness," and "anger." To learn these complex conceptual emotion categories, humans must first be able to perceive regularities in expressive behaviors (e.g., facial configurations) across individuals. Recent research suggests that infants spontaneously form "basic-level" categories of facial configurations (e.g., happy vs. fear), but not "superordinate" categories of facial configurations (e.g., positive vs. negative). The current studies further explore how infant age and language impact superordinate categorization of facial configurations associated with different negative emotions. Across all experiments, infants were habituated to one person displaying facial configurations associated with anger and disgust. While 10-month-olds formed a category of person identity (Experiment 1), 14-month-olds formed a category that included negative facial configurations displayed by the same person (Experiment 2). However, neither age formed the hypothesized superordinate category of negative valence. When a verbal label ("toma") was added to each of the habituation events (Experiment 3), 10-month-olds formed a category similar to 14-month-olds in Experiment 2. These findings intersect a larger conversation about the nature and development of children's emotion categories and highlight the importance of considering developmental processes, such as language learning and attentional/memory development, in the design and interpretation of infant categorization studies.

Eleven-Month-Olds Link Sound Properties With Animal Categories

We examined 11-month-olds' tendency to generalize properties to category members, an ability that may contribute to the inductive reasoning abilities observed in later developmental periods. Across three experiments, we tested 11-month-olds' (N = 113) generalization of properties within the cat and dog categories. In each experiment, infants were familiarized to animal-sound pairings (i.e., dog barking; cat meowing) and tested on this association and the generalization of the sound property to new members of the familiarized categories. After familiarization with a single exemplar, 11-month-olds generalized the sound to new category members that were both highly similar and less similar to the familiarized animal (Experiment 1). When familiarized with mismatched animal-sound pairings (Experiment 2; i.e., dog meowing; cat barking), 11-month-olds did not learn or generalize the sound properties, suggesting that infants have pre-existing expectations about the links between the characteristic sound properties and the animal categories. When familiarized with unfamiliar sound-animal pairings (Experiment 3; i.e., dog-unfamiliar sound), 11-month-olds linked the animals with the novel sounds but did not generalize to new category members. Taken together, these findings highlight the conditions under which young infants generalize properties from one exemplar to other category members.

Infant categorization as a dynamic process linked to memory

Recency effects are well documented in the adult and infant literature: recognition and recall memory are better for recently occurring events. We explore recency effects in infant categorization, which does not merely involve memory for individual items, but the formation of abstract category representations. We present a computational model of infant categorization that simulates category learning in 10-month-olds. The model predicts that recency effects outweigh previously reported order effects for the same stimuli. According to the model, infant behaviour at test should depend mainly on the identity of the most recent training item. We evaluate these predictions in a series of experiments with 10-month-old infants. Our results show that infant behaviour confirms the model's prediction. In particular, at test infants exhibited a preference for a category outlier over the category average only if the final training item had been close to the average, rather than distant from it. Our results are consistent with a view of categorization as a highly dynamic process where the end result of category learning is not the overall average of all stimuli encountered, but rather a fluid representation that moves depending on moment-to-moment novelty. We argue that this is a desirable property of a flexible cognitive system that adapts rapidly to different contexts.

The development of mental rotation ability across the first year after birth

Mental rotation (MR) is the ability to imagine the appearance of an object from a different perspective. This ability is involved in many human cognitive and behavioral activities. We discuss studies that have examined MR in infants and its development across the first year after birth. Despite some conflicting findings across these studies, several conclusions can be reached. First, MR may be available to human infants as young as 3 months of age. Second, MR processes in infancy may be similar or identical to MR processes later in life. Third, there may be sex differences in MR performance, in general favoring males. Fourth, there appear to be multiple influences on infants' MR performance, including infants' motor activity, stimulus complexity, hormones, and parental attitudes. We conclude by calling for additional research to examine more carefully the causes and consequences of MR abilities early in life.

Neural correlates of individuation and categorization of other-species faces in infancy

The goal of this study was to investigate 9-month-old infants' ability to individuate and categorize other-species faces at the subordinate level. We were also interested in examining the effects of initial exposure conditions on infant categorization and individuation processes. Infants were either familiarized with a single monkey face in an individuation procedure or familiarized with multiple exemplars of monkey faces from the same species in a categorization procedure. Event-related potentials were recorded while the infants were presented: familiar faces, novel faces from the familiar species, or novel faces from a novel species. The categorization group categorized monkey faces by species at the subordinate level, whereas the individuation group did not discriminate monkey faces at the individual or subordinate level. These findings indicate initial exposure to multiple exemplars facilitates infant processing of other-species faces, and infants are efficient at subordinate-level categorization at 9 months of age.

Eye vergence responses to novel and familiar stimuli in young children

Eye vergence is the slow movement of both eyes in opposite directions enabling binocular vision. Recently, it was suggested that vergence could be involved in orienting visual attention and memory having a role in cognitive processing of sensory information. In the present study, we assessed whether such vergence responses are observed in early childhood. We measured eye vergence responses in 43 children (12-37 months of age) while looking at novel and repeated object images. Based on previous research, we hypothesized that visual attention and Visual Short-Term Memory (VSMT) would be evidenced by differential vergence responses for both experimental conditions, i.e. repeated (familiar) vs. novel items. The results show that attention related vergence is present in early childhood and that responses to repeated images differ from the ones to novel items. Our current findings suggest that vergence mechanisms could be linking visual attention with short-term memory recognition.

Speech Facilitates the Categorization of Motions in 9-Month-Old Infants

Two experiments were used to investigate the influence of both native and non-native speech on the categorization of a set of an object's motions by 9-month-olds. In Experiment 1, infants were habituated to a set of three object motions and tested with familiar and novel motions. Results of Experiment 1 show that infants were more likely to categorize the motion stimuli if they listened to either the native or non-native speech during the categorization process than if they listened to music or heard nothing at all. Results of Experiment 2 show that discrimination of the motions was not impaired by the presence of the labeling phrases. These results are consistent with a number of findings that report a unique influence of labels on categorization of static objects in infancy and extend those findings to categorization of motions.

Developmental Differences in Infants' Fairness Expectations From 6 to 15 Months of Age

The present research investigated the developmental trajectory of infants' fairness expectations from 6 to 15 months of age (N = 150). Findings revealed a developmental transition in infants' fairness expectations between 6 and 12 months, as indicated by enhanced visual attention to unfair outcomes of resource distribution events (a 3:1 distribution) relative to fair outcomes (a 2:2 distribution). The onset of naturalistic sharing behavior predicted infants' fairness expectations at transitional ages. Beyond this period of developmental transition, the presence of siblings and infants' prompted giving behavior predicted individual differences in infants' fairness concerns. These results provide evidence for the role of experience in the acquisition of fairness expectations and reveal early individual differences in such expectations.

Use of evidence in a categorization task: analytic and holistic processing modes

Category learning performance can be influenced by many contextual factors, but the effects of these factors are not the same for all learners. The present study suggests that these differences can be due to the different ways evidence is used, according to two main basic modalities of processing information, analytically or holistically. In order to test the impact of the information provided, an inductive rule-based task was designed, in which feature salience and comparison informativeness between examples of two categories were manipulated during the learning phases, by introducing and progressively reducing some perceptual biases. To gather data on processing modalities, we devised the Active Feature Composition task, a production task that does not require classifying new items but reproducing them by combining features. At the end, an explicit rating task was performed, which entailed assessing the accuracy of a set of possible categorization rules. A combined analysis of the data collected with these two different tests enabled profiling participants in regard to the kind of processing modality, the structure of representations and the quality of categorial judgments. Results showed that despite the fact that the information provided was the same for all participants, those who adopted analytic processing better exploited evidence and performed more accurately, whereas with holistic processing categorization is perfectly possible but inaccurate. Finally, the cognitive implications of the proposed procedure, with regard to involved processes and representations, are discussed.

Sample size, statistical power, and false conclusions in infant looking-time research

Infant research is hard. It is difficult, expensive, and time consuming to identify, recruit and test infants. As a result, ours is a field of small sample sizes. Many studies using infant looking time as a measure have samples of 8 to 12 infants per cell, and studies with more than 24 infants per cell are uncommon. This paper examines the effect of such sample sizes on statistical power and the conclusions drawn from infant looking time research. An examination of the state of the current literature suggests that most published looking time studies have low power, which leads in the long run to an increase in both false positive and false negative results. Three data sets with large samples (>30 infants) were used to simulate experiments with smaller sample sizes; 1000 random subsamples of 8, 12, 16, 20, and 24 infants from the overall samples were selected, making it possible to examine the systematic effect of sample size on the results. This approach revealed that despite clear results with the original large samples, the results with smaller subsamples were highly variable, yielding both false positive and false negative outcomes. Finally, a number of emerging possible solutions are discussed.

Plasticity may change inputs as well as processes, structures, and responses

Significant work has documented neuroplasticity in development, demonstrating that developmental pathways are shaped by experience. Plasticity is often discussed in terms of the results of differences in input; differences in brain structures, processes, or responses reflect differences in experience. In this paper, I discuss how developmental plasticity also effectively changes input into the system. That is, structures and processes change in response to input, and those changed structures and processes influence future inputs. For example, plasticity may change the pattern of eye movements to a stimulus, thereby changing which part of the scene becomes the input. Thus, plasticity is not only seen in the structures and processes that result from differences in experience, but also is seen in the changes in the input as those structures and processes adapt. The systematic study of the nature of experience, and how differences in experience shape learning, can contribute to our understanding of neuroplasticity in general.

Seeing double: 5-month-olds' mental rotation of dynamic, 3D block stimuli presented on dual monitors

Mental rotation (MR) involves the ability to predict how an object will look once it has been rotated into a new orientation in space. To date, studies of MR in infants have tested this ability using abstract stimuli presented using a single display. Evidence from existing studies suggests that using multiple displays may affect an infant's performance in some kinds of MR tasks. This study used Moore & Johnson's (2008) simplified Shepard-Metzler objects in a dual-monitor MR task presented to five-month-old infants. Evidence for MR in infancy was found. These findings have implications for MR testing in infancy and the influence of display properties on infant MR performance.

Seeing the unseen: Second-order correlation learning in 7- to 11-month-olds

We present four experiments with the object-examining procedure that investigated 7-, 9-, and 11-month-olds' ability to associate two object features that were never presented simultaneously. In each experiment, infants were familiarized with a number of 3D objects that incorporated different correlations among the features of those objects and the body of the objects (e.g., Part A and Body 1, and Part B and Body 1). Infants were then tested with objects with a novel body that either possessed both of the parts that were independently correlated with one body during familiarization (e.g., Part A and B on Body 3) or that were attached to two different bodies during familiarization. The experiments demonstrate that infants as young as 7months of age are capable of this kind of second-order correlation learning. Furthermore, by at least 11months of age infants develop a representation for the object that incorporates both of the features they experienced during training. We suggest that the ability to learn second-order correlations represents a powerful but as yet largely unexplored process for generalization in the first years of life.

The Development of Selective Attention Orienting is an Agent of Change in Learning and Memory Efficacy

The present study examined whether the developmental transition from facilitation-based orienting mechanisms available very early in life to selective attention orienting (e.g., inhibition of return, IOR) promotes better learning and memory in infancy. We tested a single age group (4-month-olds) undergoing rapid development of attention orienting mechanisms. Infants completed a spatial cueing task designed to elicit IOR, in which cat or dog category exemplars consistently appeared in either the cued or noncued locations. Infants were subsequently tested on a visual paired comparison of exemplars from these cued and noncued animal categories. As expected, infants showed either facilitation-based orienting or the more mature IOR-based orienting during spatial cueing/encoding. Infants who demonstrated IOR-based orienting showed memory for both specific exemplars and broader category learning, whereas those who showed facilitation-based orienting showed weaker evidence of learning. Attention orienting also interacted with previous pet experience, such that the number of pets at home influenced learning only when infants engaged facilitation-based orienting during encoding. Learning in the context of IOR-based orienting was stable regardless of pet experience, suggesting that selective attention serves as an online learning mechanism during visual exploration that is less sensitive to prior experience.

The Development of Body Structure Knowledge in Infancy

Although we know much about the development of face processing, we know considerably less about the development of body knowledge-despite bodies also being significant sources of social information. One set of studies indicated that body structure knowledge is poor during the 1st year of life and spawned a model that posits that, unlike the development of face knowledge, which benefits from innate propensities and dedicated learning mechanisms, the development of body knowledge relies on general learning mechanisms and develops slowly. In this article, we review studies on infants' knowledge about the structure of bodies and their processing of gender and emotion that paint a different picture. Although questions remain, a general social cognition system likely engenders similar trajectories of development of knowledge about faces and bodies, and may equip developing infants with the capacity to obtain socially critical information from many sources.

Asymmetries in infants' attention toward and categorization of male faces: The potential role of experience

Infants typically have a preponderance of experience with females, resulting in visual preferences for female faces, particularly high attractive females, and in better categorization of female relative to male faces. We examined whether these abilities generalized to infants' visual preferences for and categorization of perceptually similar male faces (i.e., low masculine males). We found that 12-month-olds visually preferred high attractive relative to low attractive male faces within low masculine pairs only (Experiment 1) but did not visually prefer low masculine relative to high masculine male faces (Experiment 2). Lack of visual preferences was not due to infants' inability to discriminate between the male faces (Experiments 3 and 4). The 12-month-olds categorized low masculine, but not high masculine, male faces (Experiment 5). Infants could individuate male faces within each of the categories (Experiment 6). The 12-month-olds' attention toward and categorization of male faces may reflect a generalization of their female facial expertise.

Near or far: The effect of spatial distance and vocabulary knowledge on word learning

The current study investigated the role of spatial distance in word learning. Two-year-old children saw three novel objects named while the objects were either in close proximity to each other or spatially separated. Children were then tested on their retention for the name-object associations. Keeping the objects spatially separated from each other during naming was associated with increased retention for children with larger vocabularies. Children with a lower vocabulary size demonstrated better retention if they saw objects in close proximity to each other during naming. This demonstrates that keeping a clear view of objects during naming improves word learning for children who have already learned many words, but keeping objects within close proximal range is better for children at earlier stages of vocabulary acquisition. The effect of distance is therefore not equal across varying vocabulary sizes. The influences of visual crowding, cognitive load, and vocabulary size on word learning are discussed.

Infant categorization

In this article, we review the principal findings on infant categorization from the last 30 years. The review focuses on behaviorally based experiments with visual preference, habituation, object examining, sequential touching, and inductive generalization procedures. We propose that although this research has helped to elucidate the 'what' and 'when' of infant categorization, it has failed to clarify the mechanisms that underpin this behavior and the development of concepts. We outline a number of reasons for why the field has failed in this regard, most notably because of the context-specific nature of infant categorization and a lack of ground rules in interpreting data. We conclude by suggesting that one remedy for this issue is for infant categorization researchers to adopt more of an interdisciplinary approach by incorporating imaging and computational methods into their current methodological arsenal. WIREs Cogn Sci 2010 1 894-905 For further resources related to this article, please visit the WIREs website.

Not taking the easy road: When similarity hurts learning

Two experimental studies examined the effects of example format and example similarity on mathematical problem solving across different learning contexts. Participants were more successful inducing a correct problem-solving rule when they were provided with annotated examples rather than nonannotated examples. The effects of example similarity varied depending on learning context. In Experiment 1, by presenting an example and problem simultaneously, a direct comparison was possible between the cases. When the examples were similar, participants relied on superficial analogies that hurt learning. When an example was dissimilar from the given problem, participants appeared to study the example first to induce a solution procedure and then apply the rule to the problem, thus resulting in better learning and transfer. However, in Experiment 2 where the example and problem were presented in a sequential manner, the effect disappeared because the learning context did not support a direct comparison. We conclude that comparison is not inherently good for promoting learning and transfer, rather its effect depends on whether it supports relational mapping that is essential for schema acquisition.

Experience and distribution of attention: Pet exposure and infants' scanning of animal images

Although infants' cognitions about the world must be influenced by experience, little research has directly assessed the relation between everyday experience and infants' visual cognition in the laboratory. Eye-tracking procedures were used to measure 4-month-old infants' eye-movements as they visually investigated a series of images. Infants with pet experience (N = 27) directed a greater proportion of their looking at the most informative region of animal stimuli-the head-than did infants without such experience (N = 21); the two groups of infants did not differ in their scanning of images of human faces or vehicles. Thus, infants' visual cognitions are influenced by everyday experience, and theories of cognitive development in infancy must account for the effect of experience on development.

Infants' Visual Recognition Memory for a Series of Categorically Related Items

We examined the interactions between visual recognition memory, working memory, and categorization by examining 6-month-old infants' (N = 168) memory for individual items in a categorized list (e.g., images of dogs or cats). In Experiments 1 and 2, infants were familiarized with 6 different cats or dogs, presented one at a time on a series of 15-s familiarization trials. When the test occurred immediately after the sixth familiarization trial (Experiment 1), infants showed strong novelty preference for items presented on the fourth or fifth familiarization trial, but not for the items presented on the first three trials or on the sixth trial. When a brief (15-s) retention delay occurred between the end of the sixth trial and the test trials (Experiment 2), memory for the sixth item was enhanced, memory for the fourth item was impaired, and memory for the fifth was unchanged relative to when no retention delay was included. Experiment 3 confirmed that infants can form a memory for the first item presented. These results reveal how factors such as interference and time to consolidate influence infants' visual recognition memory as they categorize a series of items.

Autonomy in action: linking the act of looking to memory formation in infancy via dynamic neural fields

Looking is a fundamental exploratory behavior by which infants acquire knowledge about the world. In theories of infant habituation, however, looking as an exploratory behavior has been deemphasized relative to the reliable nature with which looking indexes active cognitive processing. We present a new theory that connects looking to the dynamics of memory formation and formally implement this theory in a Dynamic Neural Field model that learns autonomously as it actively looks and looks away from a stimulus. We situate this model in a habituation task and illustrate the mechanisms by which looking, encoding, working memory formation, and long-term memory formation give rise to habituation across multiple stimulus and task contexts. We also illustrate how the act of looking and the temporal dynamics of learning affect each other. Finally, we test a new hypothesis about the sources of developmental differences in looking.

Bootstrapping the mind: analogical processes and symbol systems

Human cognition is striking in its brilliance and its adaptability. How do we get that way? How do we move from the nearly helpless state of infants to the cognitive proficiency that characterizes adults? In this paper I argue, first, that analogical ability is the key factor in our prodigious capacity, and, second, that possession of a symbol system is crucial to the full expression of analogical ability.

5-Month-Olds' Categorization of Novel Objects: Task and Measure Dependence

To examine key parameters of the initial conditions in early category learning, two studies compared 5-month-olds' object categorization between tasks involving previously unseen novel objects, and between measures within tasks. Infants in Experiment 1 participated in a visual familiarization / novelty preference (VFNP) task with 2D stimulus images. Infants provided no evidence of categorization by either their looking or their examining even though infants in previous research systematically categorized the same objects by examining when they handled them in 3D. Infants in Experiment 2 participated in a VFNP task with 3D stimulus objects that allowed visual examination of objects' 3D instantiation while denying manual contact with the objects. Under these conditions, infants demonstrated categorization by examining but not by looking. Focused examination appears to be a key component of young infants' ability to form category representations of novel objects, and 3D instantiation appears to better engage such examining.