Form categorization in 10-month-olds

Does Human Touch Facilitate Object Categorization in 6-to-9-Month-Old Infants?

Infants form object categories in the first months of life. By 3 months and throughout the first year, successful categorization varies as a function of the acoustic information presented in conjunction with category members. Here we ask whether tactile information, delivered in conjunction with category members, also promotes categorization. Six- to 9-month-olds participated in an object categorization task in either a touch-cue or no-cue condition. For infants in the touch-cue condition, familiarization images were accompanied by precisely-timed light touches from their caregivers; infants in the no-cue condition saw the same images but received no touches. Only infants in the touch-cue condition formed categories. This provides the first evidence that touch may play a role in supporting infants' object categorization.

The development of categorisation and conceptual thinking in early childhood: methods and limitations

We present a systematic and qualitative review of academic literature on early conceptual development (0–24 months of age), with an emphasis on methodological aspects. The final sample of our review included 281 studies reported in 115 articles. The main aims of the article were four: first, to organise studies into sets according to methodological similarities and differences; second, to elaborate on the methodological procedures that characterise each set; third, to circumscribe the empirical indicators that different sets of studies consider as proof of the existence of concepts in early childhood; last, to identify methodological limitations and to propose possible ways to overcome them. We grouped the studies into five sets: preference and habituation experiments, category extension tasks, object sorting tasks, sequential touching tasks and object examination tasks. In the “Results” section, we review the core features of each set of studies. In the “Discussion” and “Conclusions” sections, we describe, for one thing, the most relevant methodological shortcomings. We end by arguing that a situated, semiotic and pragmatic perspective that emphasises the importance of ecological validity could open up new avenues of research to better understand the development of concepts in early childhood.

Second-Order Correlation Learning of Dynamic Stimuli: Evidence from Infants and Computational Modeling

We present two habituation experiments that examined 20- and 26-month-olds' ability to engage in second-order correlation learning for static and dynamic features, whereby learned associations between two pairs of features (e.g., P and Q, P and R) are generalized to the features that were not presented together (e.g., Q and R). We also present results from an associative learning mechanism that was implemented as an autoencoder parallel distributed processing (PDP) network in which second-order correlation learning is shown to be an emergent property of the dynamics of the network. The experiments and simulation demonstrate that 20- and 26-month-olds as well as neural networks are capable of second-order correlation learning in a category context for internal features of dynamic objects. However, the model predicts-and Experiment 3 demonstrates-that 20- and 26-month-olds are unable to encode second-order correlations in a noncategory context for dynamic objects with internal features. It is proposed that the ability to learn second-order correlations represents a powerful but as yet unexplored process for generalization in the first years of life.

Infants' preference for individual agents within chasing interactions

Infants, like adults, are able to discriminate between chasing and non-chasing interactions when watching animations with simple geometric shapes. But where infants derive the necessary information for discrimination and how chasing detection influences later visual attention has been previously unexplored. Here, using eye tracking, we investigated how 5- and 12-month-old infants (N=94) distribute their visual attention among individual members within different interactions depending on a type of interaction. Infant gaze was examined when observing animations depicting chasing and following interactions compared with animations displaying randomly moving shapes. Results demonstrate that when observing chasing and following interactions, all infants strongly preferred to attend to the agent that initiates an interaction and trails behind another. Low-level features, such as changes in agent-specific velocity profiles, could not account for this preference (Study 2). Rather, the strong preference for the agent going behind seems to be dependent on the initial goal-directed or "heat-seeking" motion of one agent toward another (Study 3). The current set of experiments suggests that, similar to adults, 5-months-olds' visual attention depends on the motion features of an individual agent within the interaction and is fine-tuned to agents that display goal-directed motion toward other agents.

Using a single feature to discriminate and form categories: the interaction between color, form and exemplar number

There is relatively little work that has focused on how infants use a single feature to discriminate objects or flexibly group objects together. Existing research suggests that the ease with which infants learn form and color discriminations is not equal. However, which of these dimensions is easier when discriminating between objects is still unclear. The studies in this paper tested how infants used these two dimensions under varying levels of diversity in a discrimination task. Combining traditional analyses with latent-states Markov-modeling, infant learning in these studies was characterized by a bend of overt behavior and attentional processes. Infants were able to learn both a color and form-based discrimination, but only generalized the form distinction to new stimuli. When presented with diversity on the irrelevant dimension, infants in the form condition learned quickly. However, infants in the color-condition did not show signs that they learned the distinction. The results show that infants could use both dimensions to distinguish between objects, but that form-based distinctions were easier and more likely to be generalized to new objects.

Ten-month-olds' selective use of visual dimensions in category learning

There is now general consensus that infants can use several different visual properties as the basis for categorization. Nonetheless, little is known about when and whether infants can be guided by contextual information to select the relevant properties from amongst those available to them. We show here that by 10 months of age infants can be biased, through observational learning, to use one or the other of two object properties for classification. Two groups of infants watched an actress classifying objects by either shape (the Shape group) or surface pattern (the Pattern group). When subsequently presented with two test trials which contradicted either one or the other of the classification rules, infants in the two groups looked longer to the classification event that was incompatible with the rule that group had been familiarized to. These results are discussed with reference to the development of selective feature processing in infancy.

What does it look like and what can it do? Category structure influences how infants categorize

Despite a large body of research demonstrating the kinds of categories to which infants respond, few studies have directly assessed how infants' categorization unfolds over time. Four experiments used a visual familiarization task to evaluate 10-month-old infants' (N = 98) learning of exemplars characterized by commonalities in appearance or function. When learning exemplars with a common function, infants initially responded to the common feature, apparently forming a category, and only learned the individual features with more extensive familiarization. When learning exemplars with a common appearance, infants initially learned the individual features and apparently only formed a category with more extensive familiarization. The results are discussed in terms of models of category learning.

The stability and flexibility of spatial categories

Four experiments examined the flexibility and stability with which children and adults organize locations into categories based on their spatiotemporal experience with locations. Seven-, 9-, 11-year-olds, and adults learned the locations of 20 objects in an open, square box. During learning, participants experienced the locations in four spatiotemporally defined groups (i.e., four sets of nearby locations learned together in time). At test, participants attempted to place the objects in the correct locations without the aid of the dots marking the locations. Children and adults displaced the objects toward the corners of the box consistent with the organization they experienced during learning, suggesting that they used spatiotemporal experience to organize the locations into groups. Importantly, the pattern of organization remained the same following a long delay for all four age groups, demonstrating stability. For adults, this organization shifted after a new pattern of spatiotemporal experience was introduced, suggesting that adults' categories based on spatiotemporal experience are quite flexible. Children only exhibited flexibility when the new pattern of spatiotemporal organization was consistent with available perceptual cues, demonstrating that the flexibility with which children organize locations into categories is intimately tied to both remembered and perceptual sources of information.

Sensitization during visual habituation sequences: procedural effects and individual differences

Although individual differences in visual habituation have long been interpreted in terms of processes derived from comparator theory, research over the last decade has suggested that arousal or arousability as manifest in sensitization may contribute to infants' attentional profiles, and thus, to individual differences in those profiles. We explored this possibility by habituating 4-month-old infants to 4 x 4, 10 x 10, or 20 x 20 checkerboards in a fixed-trial paradigm. The first specific aim was to examine the attentional characteristics of infants with habituation patterns showing sensitization versus those that did not. The second specific aim was to determine whether patterns of attention suggestive of sensitization effects reported in past research might be attributable to the use of illuminated interstimulus intervals (ISIs). Trends were observed for sensitization to occur more frequently with more complex than with less complex checkerboards. Infants who showed looking patterns characteristic of sensitization looked longer and did not habituate as readily as infants who did not show sensitization. Finally, different ISIs did not engender different levels of sensitization, but dark ISIs significantly increased infants' looking times to stimuli during trials.

Basic-level and superordinate-like categorical representations in early infancy

A series of experiments using the paired-preference procedure examined 3- to 4-month-old infants' ability to form perceptually based categorical representations in the domains of natural kinds and artifacts and probed the underlying organizational structure of these representations. Experiments 1 and 2 found that infants could form categorical representations for chairs that excluded exemplars of couches, beds, and tables and also for couches that excluded exemplars of chairs, beds, and tables. Thus, the adult-like exclusivity shown by infants in the categorization of various animal pictures at the basic-level extends to the domain of artifacts as well--an ecologically significant ability given the numerous artifacts that populate the human environment. Experiments 3 and 4 examined infants' ability to form superordinate-like or global categorical representations for mammals and furniture. It was found that infants could form a global representation for mammals that included novel mammals and excluded other non-mammalian animals such as birds and fish as well as items from cross-ontological categories such as furniture. In addition, it was found that infants formed a representation for furniture that included novel categories of furniture and excluded exemplars from the cross-ontological category of mammals; however, it was less clear if infants' global representation for furniture also excluded other artifacts such as vehicles and thus the category of furniture may have been less exclusively represented. Overall, the present findings, by showing the availability of perceptually driven basic and superordinate-like representations in early infancy that closely correspond to adult conceptual categories, underscore the importance of these early representations for later conceptual representations.