Ellen M. Markman

Categories and induction in young children.

Abstract One of the primary functions of natural kind terms (e.g., tiger, gold) is to support inductive inferences. People expect members of such categories to share important, unforeseen properties, such as internal organs and genetic structure. Moreover, inductions can be made without perceptual support: even when an object does not look much like other members of its category, and even when a property is unobservable. The present work addresses how expectations about natural kinds originate. Young children, with their usual reliance on perceptual appearances and only rudimentary scientific knowledge, might not induce new information within natural kind categories. To test this possibility, category membership was pitted against perceptual similarity in an induction task. For example, children had to decide whether a shark is more likely to breathe as a tropical fish does because both are fish, or as a dolphin does because they look alike. By at least age 4, children can use categories to support inductive inferences even when category membership conflicts with appearances. Moreover, these young children have partially separated out properties that support induction within a category (e.g., means of breathing) from those that are in fact determined by perceptual appearances (such as weight). Since we examined only natural kind categories, we do not know to what extent children have differentiated natural kinds from other sorts of categories. Children may start out assuming that categories named by language have the structure of natural kinds and with development refine these expectations.

Children's use of mutual exclusivity to constrain the meanings of words ☆

For children to acquire vocabulary as rapidly as they do, they must be able to eliminate many potential meanings of words. One way children may do this is to assume category terms are mutually exclusive. Thus, if a child already knows a label for an object, a new label for that object should be rejected. Six studies with 3-year-olds tested this hypothesis. Study 1 demonstrated that children reject a second label for an object, treating it, instead, as a label for a novel object. In the remaining studies, this simple novel label-novel object strategy was precluded. If the only object present is familiar, children cannot map a novel term to a novel object. Instead they must analyze the object for some other attribute to label. In Studies 2–6, children were taught either a new part term, e.g., trachea, or a new substance term, e.g., pewter, by showing them an object and saying, “This is a trachea” or (“It is pewter”). For unfamiliar objects, children tended to interpret the term as a label for the object itself. For familiar objects, they tended instead to interpret it as a part or substance term. Thus, mutual exclusivity motivates children to learn terms for attributes, substances, and parts as well as for objects themselves.

Realizing that You Don't Understand: Elementary School Children's Awareness of Inconsistencies.

2 factors were proposed to affect awareness of ones comprehension failure: the inferential processing requirements, and the kind of standards against which comprehension is evaluated. These studies investigated elementary school childrens awareness of their own comprehension failure when presented with inconsistent information. Study 1 showed that children were more likely to notice explicit than implicit contradictions. However, even 12-year-olds judged as comprehensible a sizable proportion of essays with seemingly obvious inconsistencies. Yet, the children had good probed recall of the information, the logical capacity to draw the inferences, and were not generally reluctant to question the experimenter. In subsequent studies children were (a) asked to repeat sentences in order to guarantee that the 2 inconsistent propositions were concurrently activated in working memory, and (b) warned about the existence of a problem in order to promote more careful evaluation. Taken together, the results suggest that to notice inconsistencies children have to encode and store the information, draw the relevant inferences, retrieve and maintain the (inferred) propositions in working memory, and compare them. Third through sixth graders do not spontaneously carry out those processes that they are capable of carrying out.

Word Learning in Children: An Examination of Fast Mapping.

Children may be able to gain at least partial information about the meaning of a word from how it is used in a sentence, what words it is contrasted with, as well as other factors. This strategy, known as fast mapping, may allow the child to quickly hypothesize about the meaning of a word. It is not yet known whether this strategy is available to children in semantic domains other than color. In the first study, 2-, 3-, and 4-year-olds were introduced to a novel color, shape, or texture word by contrasting the new term with a well-known word from that domain. They were then tested for their ability to produce and comprehend the new term and for whether they knew what semantic domain the word referred to. The results show that even 2-year-old children can quickly narrow down the meaning of a word in each of the semantic domains examined, although children learned more about shape terms than color or texture words. A second study explored the effects of several variables on childrens ability to infer the meaning of a new term. One finding of this study was that if the context is compelling, children can figure out the meaning of a new word even without hearing an explicit linguistic contrast.

Use of the mutual exclusivity assumption by young word learners

A critical question about early word learning is whether word learning constraints such as mutual exclusivity exist and foster early language acquisition. It is well established that children will map a novel label to a novel rather than a familiar object. Evidence for the role of mutual exclusivity in such indirect word learning has been questioned because: (1) it comes mostly from 2 and 3-year-olds and (2) the findings might be accounted for, not by children avoiding second labels, but by the novel object which creates a lexical gap children are motivated to fill. Three studies addressed these concerns by having only a familiar object visible. Fifteen to seventeen and 18-20-month-olds were selected to straddle the vocabulary spurt. In Study 1, babies saw a familiar object and an opaque bucket as a location to search. Study 2 handed babies the familiar object to play with. Study 3 eliminated an obvious location to search. On the whole, babies at both ages resisted second labels for objects and, with some qualifications, tended to search for a better referent for the novel label. Thus mutual exclusivity is in place before the onset of the naming explosion. The findings demonstrate that lexical constraints enable babies to learn words even under non-optimal conditions--when speakers are not clear and referents are not visible. The results are discussed in relation to an alternative social-pragmatic account.

Subtle Linguistic Cues Affect Children's Motivation

Are preschoolers’ reactions to setbacks influenced by whether their successes are rewarded with generic or nongeneric praise? Previous research has focused on the role of category-referring generics (e.g., ‘‘Dogs are friendly’’) in shaping children’s knowledge about natural kinds (see Gelman, 2004). Generic sentences can, however, refer to individuals as well as categories. For example, ‘‘John is friendly’’ is generic because it reports a general regularity—albeit about a single person—rather than a particular fact or episode (Carlson & Pelletier, 1995). In contrast, the nongeneric ‘‘John was friendly at the party’’ refers to a specific past event. Generic sentences about an individual imply that the particular behavior commented on (e.g., John smiling warmly) stems from a stable trait (e.g., friendliness) or skill (see Gelman & Heyman, 1999). Are children sensitive to this subtle connotation with respect to their own behavior? If so, then generic praise may lead children to think in trait terms, such that later mistakes could signal a negative trait or low ability and therefore undermine motivation (Dweck, 1999, 2006). Preliminary support for this claim comes from a study by Kamins and Dweck (1999). Praising the whole person (e.g., ‘‘You are a good boy/girl’’) after success on a task fostered helpless responses to subsequent mistakes more than praising the process through which success was achieved (e.g., ‘‘You found a good way to do it’’). We suggest that children’s behavior was in part driven by the fact that the person praise was generic, connoting a stable trait of the child, while the process praise was nongeneric, focusing on one specific episode. Would manipulating only the genericness of the praise result in similar patterns of coping? For example, would children’s motivation be affected differently by ‘‘You are a good drawer’’ (generic) than by ‘‘You did a good job drawing’’ (nongeneric)? Note that these sentences are much more similar than the person-process pairs used by Kamins and Dweck—so similar, in fact, that adults may not be aware of their contrasting implications and are thus likely to use them interchangeably in interactions with children. Demonstrating that children praised in these two ways react differently to a challenge would be evidence for the importance of the generic/nongeneric distinction in shaping young children’s conceptions of their abilities.

Developmental Differences in the Acquisition of Basic and Superordinate Categories.

HORTON, MARJORIE S., and MARKMAN, ELLEN M. Developmental Differences in the Acquisition of Basic and Superordinate Categories. CHILD DEVELOPMENT, 1980, 51, 708-719. This study examined the relative utility of exemplar and linguistic information for acquiring basic and superordinate categories. The perceptual similarity among members of basic categories suggests that a child could learn these categories simply from exposure to exemplars. The dissimilarity among members of superordinate categories suggests a child would also need to be informed of the relevant criteria for categorization. Developmental differences were predicted in the ability to benefit from the linguistically specified criterial information. These hypotheses were tested by having preschool, kindergarten, and first-grade children learn artificial animal categories. Each child was trained on 1 category through exemplar information alone and 1 through exemplar information supplemented with linguistic descriptions of criterial properties. The results supported the hypotheses: Linguistic information facilitated acquisition of only superordinate, not basic level, categories, and only for the older children. These findings indicate that the internal structure of categories and the processing abilities of the learner are important determinants of acquisition.

Classes and collections: Internal organization and resulting holistic properties ☆

Abstract This work presents an analysis of a type of concept, the collection, not readily characterized by class inclusion models. Collections, the referents of collective nouns (e.g., pile, family, bunch), are argued to differ from classes in (a) how membership can be determined, (b) part-whole relationships, (c) internal structure, and (d) the nature of the higher order units they form. From this analysis, it is hypothesized that the psychological integrity of collections is greater than that of classes. Collections and objects, in contrast to classes, both require specified relationships among the parts and both result in a coherent psychological unit. It was suggested that objects form a relatively more stable unit than collections. Corresponding to this analysis the degree of psychological integrity is hypothesized to lead to different degrees of difficulty in making part-whole comparisons for objects, collections, and classes in modified Piagetian class-inclusion paradigms. The hypothesized difference in performance was found for collections and classes and an alternative linguistic explanation for the greater success with collections was eliminated. However, children performed equally well on tasks involving collections and objects, raising the possibility that when elements are organized into collections, they form psychological units which are as coherent as objects.

Constraints on word meaning in early language acquisition

Very young children successfully acquire the vocabulary of their native language despite their limited information processing abilities. One partial explanation for childrens success at the inductive problem word learning presents is that children are constrained in the kinds of hypotheses they consider as potential meanings of novel words. Three such constraints are discussed: (1) the whole-object assumption which leads children to infer that terms refer to objects as a whole rather than to their parts, substance, color, or other properties; (2) the taxonomic assumption which leads children to extend words to objects or entities of like kind; and (3) the mutual exclusivity assumption which leads children to avoid two labels for the same object. Recent evidence is reviewed suggesting that all three constraints are available to babies by the time of the naming explosion. Given the importance of word learning, children might be expected to recruit whatever sources of information they can to narrow down a words meaning, including information provided by grammatical form class and the pragmatics of the situation. Word-learning constraints interact with these other sources of information but are also argued to be an especially useful source of information for children who have not yet mastered grammatical form class in that constraints should function as an entering wedge into language acquisition.

Prior Experiences and Perceived Efficacy Influence 3-Year-Olds’ Imitation

Children are selective and flexible imitators. They combine their own prior experiences and the perceived causal efficacy of the model to determine whether and what to imitate. In Experiment 1, children were randomly assigned to have either a difficult or an easy experience achieving a goal. They then saw an adult use novel means to achieve the goal. Children with a difficult prior experience were more likely to imitate the adults precise means. Experiment 2 showed further selectivity--children preferentially imitated causally efficacious versus nonefficacious acts. In Experiment 3, even after an easy prior experience led children to think their own means would be effective, they still encoded the novel means performed by the model. When a subsequent manipulation rendered the childrens means ineffective, children recalled and imitated the models means. The research shows that children integrate information from their own prior interventions and their observations of others to guide their imitation.