Language-mediated object categorization: A longitudinal study with 16- to 20-month-old Serbian-speaking children

This study addressed the development of language-mediated categorization longitudinally, on a sample of Serbian-speaking children aged 16–20 months. Twenty four children were tested 3 consecutive times on: categorization of unknown objects with a shared label and a similar shape; and categorization of unknown objects with a shared label, but no visual similarity. The task was embedded in a game-like activity which included real object manipulation, categorization of novel objects labeled with made-up names, and socio-pragmatic cues provided by the experimenter. Our results indicate that an average child develops the ability to categorize novel objects with a similar shape and a shared label around 16 months of age, whereas for novel objects with a shared label, but no visual similarity, this ability is acquired sometime between 18 and 20 months of age. Our results partly confirm research findings obtained in other languages, thus emphasizing the need for cross-linguistic and cross-cultural validation of all language-related developmental studies.     

Naming and categorization in young children: IV: listener behavior training and transfer of function

Following pretraining with everyday objects, 14 children aged from 1 to 4 years were trained, for each of three pairs of different arbitrary wooden shapes (Set 1), to select one stimulus in response to the spoken word /zog/, and the other to /vek/. When given a test for the corresponding tacts ("zog" and "vek"), 10 children passed, showing that they had learned common names for the stimuli, and 4 failed. All children were trained to clap to one stimulus of Pair 1 and wave to the other. All those who named showed either transfer of the novel functions to the remaining two pairs of stimuli in Test 1, or novel function comprehension for all three pairs in Test 2, or both. Three of these children next participated in, and passed, category match-to-sample tests. In contrast, all 4 children who had learned only listener behavior failed both the category transfer and category match-to-sample tests. When 3 of them were next trained to name the stimuli, they passed the category transfer and (for the 2 subjects tested) category match-to-sample tests. Three children were next trained on the common listener relations with another set of arbitrary stimuli (Set 2); all succeeded on the tact and category tests with the Set 2 stimuli. Taken together with the findings from the other studies in the series, the present experiment shows that (a) common listener training also establishes the corresponding names in some but not all children, and (b) only children who learn common names categorize; all those who learn only listener behavior fail. This is good evidence in support of the naming account of categorization.     

How children name objects with shoes

Many studies report a shape bias in children's learning of object names. However, one previous study suggests that the shape bias is not the only perceptually based bias displayed by children learning count nouns. Specifically, children attended to texture as well as shape when extending a novel name to novel objects with eyes. Two experiments attempt to extend this finding, asking whether children will also attend to texture in the presence of another cue to animacy—shoes. In Experiment 1, 80 2- and 3-year-olds participated in either a Name generalization or Similarity judgment task. The novel objects were identical except that for half of the children the objects had shoes. In the Similarity condition, children made their judgments by overall similarity. In the Name condition, 2-year-olds extended the novel name by shape across objects both with and without shoes. In contrast, 3-year-olds generalized the novel name by shape when the objects had no shoes but by texture when the objects had shoes. Experiment 2 challenged this finding, using a forced choice procedure and objects that differed from the named exemplar more markedly in shape. Twenty 3-year-olds participated in a Name generalization task, half for objects with shoes, half for objects without shoes. Again, children attended reliably more to texture when the objects had shoes than when they had no shoes. The results are discussed in terms of the development of different perceptually based biases and the relation of such biases to a taxonomic bias in early word learning.     

Late talkers show no shape bias in a novel name extension task

By 2½ years of age, children typically show a shape bias in object naming – that is, they extend object names mostly to new instances with the same shape. The acquisition of a shape bias is related to a marked increase in the rate of object name learning. This study asks whether, conversely, children who do not readily acquire new object names lack a shape bias. Twelve 2- to 3-year-old ‘late talkers’– children whose total vocabularies rank below the 30th percentile for their age – were compared with age-matched children with larger vocabularies in a novel object name extension task. The controls extended novel names across novel objects with the same shape. The late talkers showed no group perceptual bias, but many individuals extended novel names across objects with the same surface texture. The implications of the results both for the role of attentional biases in object name learning and for the etiology of some late talking are discussed.      

Object names and object functions serve as cues to categories for infants

Can object names and functions act as cues to categories for infants? In Study 1, 14- and 18-month-old infants were shown novel category exemplars along with a function, a name, or no cues. Infants were then asked to "find another one," choosing between 2 novel objects (1 from the familiar category and the other not). Infants at both ages were more likely to select the category match in the function than in the no-cue condition. However, only at 18 months did naming the objects enhance categorization. Study 2 shows that names can facilitate categorization for 14-month-olds as well when a hint regarding the core meaning of the objects (the function of a single familiarization object) is provided.     

It's Taking Shape: Shared Object Features Influence Novel Noun Generalizations

Children's early noun vocabularies are dominated by names for shape‐based categories. However, along with shape, material and colour are also important features of many early categories. In the current study, we investigate how the number of shared features among objects influences children's novel noun generalizations, explanations for these generalizations and spontaneous speech. Preschool children and adults were presented with test objects that shared only one feature (e.g. shape) or that shared two features (e.g. material and colour). After each trial, participants were asked, ‘how did you know that was your [novel name]?’ Overall, participants generalized novel names on the basis of shape more when objects shared shape and a second feature with the exemplar. All participants provided shape‐based explanations of their choices, but explanations were increasingly more abstract across development. Finally, children's spontaneous speech was dominated by references to the objects' shape, and this did not change across development or number of shared features. Overall, these data demonstrate that the shape bias is enhanced when objects share shape and a second feature but weakened for 3‐year‐old children when objects share two non‐shape features. These findings have implications for our understanding of how children learn names for objects that belong to multiple categories. Copyright © 2012 John Wiley & Sons, Ltd.     

Infants' categorization of novel objects with more or less obvious features

In five experiments, 14- to 15-month-old infants' categorization of objects on the basis of more or less obvious features was investigated. Using an object examining paradigm, a total of 200 infants were familiarized with novel objects that shared either more obvious features (i.e., easily visible) or less obvious features (i.e., accessible by lifting a flap), followed by an in-category object and an out-of-category object. When only perceptual information was available, infants formed a category on the basis of the more obvious features but not on the basis of the less obvious features (Experiments 1 and 3). When infants were provided with animacy cues and/or object names, they formed categories on the basis of either more or less obvious features (Experiments 2, 4, and 5). The results of these studies delineate the role of animacy cues and object names in establishing categories on the basis of less obvious features.     

Comparison Facilitates Children's Learning of Names for Parts

Learning names for parts of objects can be challenging for children, as it requires overcoming their tendency to name whole objects. We test whether comparing items can facilitate learning names for their parts. Applying the structure-mapping theory of comparison leads to two predictions: (a) young children will find it easier to identify a common part between two very similar items than between two dissimilar items (because the similar pair is easier to align); (b) close alignments potentiate far alignments: children will be better able to extend a novel part name to a dissimilar object after having extended it to a similar object. In three studies, 227 preschool children mapped novel part terms to new animals or objects. Both predictions were confirmed. Children more accurately extended novel part terms to objects that were similar to the standard than to objects that were dissimilar (Experiments 1 and 2), and children more accurately extended novel part names to dissimilar objects after having extended them to similar objects (Experiment 3). We conclude that structure-mapping processes can support part learning.     

Core knowledge and its limits: The domain of food

Adults, preschool children, and nonhuman primates detect and categorize food objects according to substance information, conveyed primarily by color and texture. In contrast, they perceive and categorize artifacts primarily by shape and rigidity. The present experiments investigated the origins of this distinction. Using a looking time procedure, Experiment 1 extended previous findings that rhesus macaques (Macaca mulatta) generalize learning about novel food objects by color over changes in shape. Six additional experiments then investigated whether human infants show the same signature patterns of perception and generalization. Nine-month-old infants failed to detect food objects in accord with their intrinsic properties, in contrast to rhesus monkeys tested in previous research with identical displays. Eight-month-old infants did not privilege substance information over other features when categorizing foods, even though they detected and remembered this information. Moreover, infants showed the same property generalization patterns when presented with foods and tools. The category-specific patterns of perception and categorization shown by human adults, children, and adult monkeys therefore were not found in human infants, providing evidence for limits to infants’ domains of knowledge.     

Infants' reasoning about opaque and transparent occluders in an individuation task

Two experiments document that conceptual knowledge influences 3-year-olds' extension of novel words. In Experiment 1, when objects were described as having conceptual properties typical of artifacts, children extended novel labels for these objects on the basis of shape alone. When the very same objects were described as having conceptual properties typical of animate kinds, children extended novel labels for these objects on the basis of both shape and texture. Moreover, providing a salient perceptual cue (Experiment 2) did not interfere with children's reliance on conceptual information in extending novel words: when an object with eyes was labeled with a novel word in the context of a story describing the object as an artifact, children extended the label on the basis of shape alone (i.e. as though the object were an artifact). These results, which challenge directly the position that 'dumb attentional mechanisms' can account for word learning, stand as evidence for the central role of conceptual information in mapping words to meaning.     

How Children and Adults Name Broken Objects: Inferences and Reasoning About Design Intentions in the Categorization of Artifacts

If inferences about the functions intended by object designers guide the way artifacts are categorized, a broken object should still be considered a member of its original category even though it is currently dysfunctional; however, an object that appears to be dysfunctional by design should not be. Such a comparison was arranged in four studies of lexical categorization. Even with novel categories, 10-year-olds and adults preferentially included broken objects, and they did so spontaneously (Study 1). Younger children did not (Studies 1 and 2). However, when probed about the design intentions behind novel objects, 6-year-olds often inferred them correctly and then took intentions into account to categorize (Study 3). In fact, when 4-year-olds named objects derived from familiar categories, even they spontaneously used design intentions to categorize (Study 4). Accordingly, even young children provided some evidence of categorizing artifacts by inferring and reasoning about intended functions.     

What's in a shape? Children represent shape variability differently than adults when naming objects

Children and adults often generalize a word to objects of the same shape. However, the shape properties on which generalization is based are unknown. We investigated the degree to which two shape dimensions were represented categorically by children and adults when learning names for objects. Multidimensional scaling techniques were used to establish the perceptual similarity of two sets of objects in Experiment 1. In Experiments 2 and 3, children (from 2;8 to 4;5 years of age) and adults participated in two tasks in which they learned a novel name for an exemplar. We then examined how often the novel name was generalized to different objects and to line drawings of the objects. In one task, participants generalized the names from memory; in a second task the exemplar was in front of the participant during generalization. Adults accepted names more often to objects that fell "within" the proposed shape boundaries than to objects that fell "across" the boundaries. Children, however, were just as likely to generalize names to novel objects that fell within as to objects that crossed the boundaries.     

Learning Count Nouns and Adjectives: Understanding the Contributions of Lexical Form Class and Social-Pragmatic Cues

In two experiments, one hundred ninety-two 3-year-olds, 4-year-olds, and adults heard a novel word for a target object and then were asked to extend the label to one of two test objects, one matching in shape-based object category (the shape match) and the other matching in a property other than shape (the property match). We independently manipulated the lexical form class cues (count noun, adjective) and social-pragmatic cues (point actions, property-highlighting actions) accompanying the label. The impact of these two types of cue on extension differed markedly across age groups. Adults and 4-year-olds extended the word to the property match significantly more often when the term was modeled as an adjective and when it was presented with property-highlighting actions; but adults extended both adjectives and count nouns systematically to the property match when the speaker highlighted the non-shape property, whereas 4-year-olds systematically extended only adjectives to the property match under these conditions. Three-year-olds extended the word to the property match significantly more often when the label was modeled as an adjective but were not significantly affected by the social-pragmatic cues; and they failed to extend either adjectives or count nouns systematically to the property match when the speaker highlighted the non-shape property. We discuss the results in terms of the proposal that word learning draws on cues from multiple sources and the nature of the “shape bias” in lexical development.     

Comparison in the Development of Categories

Recent research on children's word learning has led to a paradox. Although word learning appears to be a deep source of insight into conceptual knowledge for children, preschoolers often categorize objects on the basis of shallow perceptual features such as shape. The current studies seek to resolve this discrepancy. We suggest that comparing multiple instances of a category enables children to extract deeper relational commonalities among category members. We examine 4-year-olds' categorization behaviors when asked to select a match for a target object (e.g., an apple) between a perceptually similar, out-of-kind object (e.g., a balloon) and a perceptually different category match (e.g., a banana). Children who learn a novel word as a label for multiple instances of the category are more likely to select the category match over the perceptual match. Children who learn a label for only one instance are equally likely to select either alternative. This effect is present even when individual target instances are more perceptually similar to the perceptual choice than to the category choice. We conclude that structural alignment processes may be important in the development of category understanding.     

The effects of type of instruction,animacy cues,and dimensionality of objects on the shape bias in 3‐ to 6‐year‐old children

Robust evidence exists for the shape bias, or children's tendency to extend novel names and categorize objects more readily on the basis of shape than on other object features. However, issues remain about the conditions that affect the shape bias and its importance as a linguistic device. In this research, we examined how type of instruction (common noun naming, proper noun naming, same kind, and goes with), animacy of objects (animate, inanimate), and dimensionality of objects (two‐dimensional, three‐dimensional) affect the shape bias in 3‐ to 6‐year‐old children. Overall, all children showed strong use of the shape bias with categorization (same kind, goes with) instructions, the former in line with the shape‐as‐cue theory. Additionally, the shape bias was quite robust in the inanimate condition, regardless of type of instruction or dimensionality of objects. However, in the animate condition, a proper noun naming instruction coupled with an animate object cue reduced the shape bias across both two‐ and three‐dimensional objects. Implications of these findings are presented.

Highlights

• This study assessed the “shape bias,” a linguistic strategy young children routinely use when confronted with the task of extending a novel name from one object to another.
• Novel name extension and categorization tasks were used in this study.
• Shape bias was affected by the type of instructions, animacy of objects, and dimensionality of objects.

     

Testing a word is not a test of word learning

Although vocabulary acquisition requires children learn names for multiple things, many investigations of word learning mechanisms teach children the name for only one of the objects presented. This is problematic because it is unclear whether children's performance reflects recall of the correct name–object association or simply selection of the only object that was singled out by being the only object named. Children introduced to one novel name may perform at ceiling as they are not required to discriminate on the basis of the name per se, and appear to rapidly learn words following minimal exposure to a single word. We introduced children to four novel objects. For half the children, only one of the objects was named and for the other children, all four objects were named. Only children introduced to one word reliably selected the target object at test. This demonstration highlights the over-simplicity of one-word learning paradigms and the need for a shift in word learning paradigms where more than one word is taught to ensure children disambiguate objects on the basis of their names rather than their degree of salience.     

The cause of infant categorization?

We asked whether infants are sensitive to causal relations between objects and outcomes and whether this sensitivity supports categorization. Fourteen- and 18-month-old infants were familiarized with objects from a novel category. For some, the objects caused an electronic toy to activate. For others, the objects were present during activation of the toy, but did not cause the event. For the remaining infants, the events were never activated. Infants were asked to select another category member from a pair of previously unseen objects (one from the familiar, and one from a novel, category). Infants were more likely to select the category match in the causal than the non-causal and no outcome conditions, suggesting that they capitalize on causal information in forming object categories.     

The role of naming in stimulus categorization by preschool children

The purpose of the current study was to assess whether children would categorize pictures when taught the relevant listener and speaker behaviors separately. A category-sort test was used to assess emergent conditional relations. Category-sort trials consisted of looking at (Test 1) or tacting/labeling (Test 2) a sample stimulus and selecting the appropriate comparison stimuli. In Experiment 1, 4 children (3-5 years) were taught to tact pictures of six U.S. state maps as either north or south. An assessment was conducted to determine whether they would (1) correctly categorize or sort when presented with a visual sample and (2) select the correct stimuli when hearing their category names (listener behavior). Two of the children categorized the pictures during Posttest 1 after the initial (pairwise) tact training. The other 2 categorized after receiving additional tact training with all pictures presented together. However, one of them categorized only during Posttest 2. In Experiment 2, 4 children (3-5 years) were taught to select pictures when hearing their category names. An assessment was conducted to determine whether they would (1) correctly categorize or sort and (2) tact the stimuli (speaker behavior). One child categorized the pictures during Posttest 1, and two during Posttest 2. The other child required additional training with all pictures grouped together. When participants failed to categorize, they also failed to tact the pictures accurately. Taken together, results from Experiments 1 and 2 show that both speaker and listener behavior play an important role in stimulus categorization.     

The shape of thought

When children learn the name of a novel object, they tend to extend that name to other objects similar in shape – a phenomenon referred to as the shape bias. Does the shape bias stem from learned associations between names and categories of objects, or does it derive from more general properties of children's understanding of language and the world? We argue here for the second alternative, presenting evidence that the shape bias emerges early in development, is not limited to names, and is intimately related to how children make sense of categories.