When less is more: how infants learn to form an abstract categorical representation of support

Two experiments explored how infants learn to form an abstract categorical representation of support (i.e., on) when habituated to few (i.e., 2) or many (i.e., 6) examples of the relation. When habituated to 2 pairs of objects in a support relation, 14-month-olds, but not 10-month-olds, formed the abstract spatial category (i.e., generalized the relation to novel objects). When habituated to 6 object pairs in a support relation, infants did not attend to the relation. The results indicate that infants learn to form an abstract spatial category of support between 10 and 14 months and that having fewer object pairs depicting this relation facilitates their acquisition of the abstract categorical representation.     

Psychological factors capable of preventing the inhibition of antibody responses in separated infant monkeys

The capacity of infant squirrel monkeys to mount an antibody response to viral challenge was evaluated after removal from their mothers in several social and physical environments. Control and separated infants were injected with a benign virus, the bacteriophage X174, and levels of neutralizing antibody were assessed for 3 weeks. Infants separated alone in an unfamiliar environment showed a significant reduction in antibody levels as compared to control infants. Allowing infants to remain in the home environment, either alone or with peers, prevented this inhibition of antibody responses from occurring. Similarly, providing familiar peers in the novel environment facilitated the normal expression of antibody responses. These results indicate that the trauma of maternal separation is significantly reduced when infants are familiar with the separation environment or familiar social companions are available. The reduced antibody response was associated with the highest level of adrenal activation induced by the unfamiliar separation condition, but antibody titers and plasma cortisol levels could not be specifically correlated in individual infants.     

Mirror-image stimulation and short separations in stumptail monkeys

Two experiments examined the responses of infant stumptail macaques (Macaco arctoides) to mirror-image stimulation (MIS) during short social separations. Overall, infants living in pairs showed agitation when separated from their partners, but were calmer when the partner, an unfamiliar peer, or their own mirror image was visible. MIS elicited more facial expressions than the familiar peer, and more affiliative contact than an unfamiliar peer. In contrast, infants reared in a group were not calmed during separations either by an unfamiliar peer or by MIS, and they exhibited some negative reactions to the mirror. Social responsiveness to MIS varies with the social background of the subjects.     

Establishing word-object relations: a first step

This work explores how infants in the early phases of acquiring language come to establish an initial mapping between objects and their labels. If infants are biased to attend more to objects in the presence of language, that could help them to note word-object object pairings. To test this, a first study compared how long 18 10-14-month-old infants looked at unfamiliar toys when labeling phrases accompanied their presentation, versus when no labeling phrases were provided. As predicted, labeling the toys increased infants' attention to them. A second study examined whether the presence of labeling phrases increased infants' attention to objects over and above what pointing, a powerful nonlinguistic method for directing infants' attention, could accomplish on its own. 22 infants from 2 age groups (10-14- and 17-20-month-olds) were shown pairs of unfamiliar toys in 2 situations: (a) in a pointing alone condition, where the experimenter pointed a number of times at one of the toys, and (b) in a labeling + pointing condition, where the experimenter labeled the target toy while pointing to it. While the pointing occurred, infants looked just as long at the target toy whether or not it was labeled. During a subsequent play period in which no labels were uttered, however, infants gazed longer at the target toys that had been labeled than at those that had not. Thus language can increase infants' attention to objects beyond the time that labeling actually occurs. These studies do not pinpoint which aspects of labeling behavior contribute to the attentional facilitation effect that was observed. In any case, however, this tendency for language to sustain infants' attention to objects may help them learn the mappings between words and objects.     

Acquisition of the same/different concept by an African Grey parrot (Psittacus erithacus): Learning with respect to categories of color,shape, and material

An African Grey parrot, previously taught to use vocal English labels to discriminate more than 80 different objects and to respond to questions concerning categorical concepts of color and shape, was trained and tested on relational concepts ofsame anddifferent. The subject, Alex, replied with the correct English categorical label (“color,” “shape,” or “mah-mah” [matter]) when asked “What’s same?” or “What’s different?” about pairs of objects that varied with respect to any combination of attributes. His accuracy was 69.7%–76.6% for pairs of familiar objects not used in training and 82.3%–85% for pairs involving objects whose combinations of colors, shapes, and materials were unfamiliar. Additional trials demonstrated that his responses were based upon the question being posed as well as the attributes of the objects. These findings are discussed in terms of his comprehension of the categories of color, shape, and material and as evidence of his competence in an exceptional (non-species-specific) communication code.     

How Two- and Four-Year-Old Children Interpret Adjectives and Count Nouns

We examined the role of object kind familiarity (i.e., knowledge of a count noun for an object) on preschoolers' sensitivity to the relation between a novel word's form class (adjective or count noun) and its reference (to a material kind-property or to an object kind). We used a forced-choice match-to-target task, in which children learned a word for one object (e.g., a metal cup), and then chose between 2 other objects. One was from the same object kind but a different material kind (with different related properties, such as color and texture; e.g., a white plastic cup); the other was from a different object kind but the same material kind (with the same related properties; e.g., a metal spoon). In Experiment 1, children learned either a count noun (e.g., "This is a zav") or an adjective (e.g., "This is a zav one"). Within each form class, we crossed the familiarity of the referent object kind (familiar and unfamiliar) with the age of the children (2- and 4-year-olds). The principal finding was that in interpreting an adjective, 4-year-olds were more likely to choose the object sharing material kind with the target if the target was familiar than if it was unfamiliar. No such familiarity effect was evident among 2-year-olds. In Experiment 2, we employed a more unambiguously adjectival frame (e.g., "This is a very zav-ish one"), and replicated the results of Experiment 1. We interpret the results in terms of 2 proposed word learning biases: one that learners initially expect any word applied to an unfamiliar object to refer to a (basic-level) kind of object, and a second that learners prefer words to contrast in meaning. We consider several interpretations of the observed age difference.     

Neural correlates of face and object recognition in young children with autism spectrum disorder,developmental delay,and typical development

This study utilized electroencephalographic recordings to examine whether young children with autism spectrum disorder (ASD) have impaired face recognition ability. High-density brain event-related potentials (ERPs) were recorded to photos of the child's mother's face versus an unfamiliar female face and photos of a favorite versus an unfamiliar toy from children with ASD, children with typical development, and children with developmental delay, all 3 to 4 years of age (N = 118). Typically developing children showed ERP amplitude differences in two components, P400 and Nc, to a familiar versus an unfamiliar face, and to a familiar versus an unfamiliar object. In contrast, children with ASD failed to show differences in ERPs to a familiar versus an unfamiliar face, but they did show P400 and Nc amplitude differences to a familiar versus an unfamiliar object. Developmentally delayed children showed significant ERP amplitude differences for the positive slow wave for both faces and objects. These data suggest that autism is associated with face recognition impairment that is manifest early in life.     

Food sharing in albino rat pups: Does familiarity breed contempt?

The present experiment investigated the effects of kinship and familiarity upon food sharing in pairs of albino rat pups. Five pairs of rats from each of the following groups were tested: (1) familiar siblings, (2) nonfamiliar siblings, (3) familiar nonsiblings, and (4) nonfamiliar non-siblings. A small food portion was used, necessitating not only close physical contact, but also cooperation in the sense that both pups were required to remain relatively immobile in order for both to feed simultaneously. Results indicated more frequent sharing among unfamiliar pups, whether related or not. Results also indicated that food sharing increased in frequency among all four groups over the 5-day testing period, suggesting that cooperation in the form of food sharing can develop, or increase in frequency, over time in albino rat pups.     

Smile production in older infants: the importance of a social recipient for the facial signal

2 studies tested the hypothesis that infant smile production depends on the availability of a social recipient for the facial signal, as well as on appropriate internal events. We examined the effects of attentive and inattentive, familiar and unfamiliar social objects on smile production in 1 1/2-year-old infants outside of social interactions. Like adults, these infants directed a majority of the smiles produced during nonsocial activity to an attentive social object. Overall smiling frequency was much lower when the only potential recipient (the mother) was inattentive, but the effect did not appear to be mediated by negative emotion. Only smiles directed to mother were reduced: nonsocial smiling (at the toys) was not sensitive to mother's inattention, and when an attentive, friendly stranger was present, she was accepted as a substitute target for social smiles. We conclude that an open channel of social communication promotes the outward expression of internal affect in infants.     

Four-month-old infants' sensitivity to binocular and kinetic information for three-dimensional-object shape

4-month-old infants were tested for sensitivity to kinetic and binocular information for 3-dimensional-object shape. The study included 2 tests: a test for sensitivity to binocular disparity and a shape perception test. The disparity sensitivity test used a preferential looking procedure developed by Held, Birch, and Gwiazda. On the basis of the results of this test, infants were assigned to disparity-sensitive and disparity-insensitive groups. In the shape perception test, a "transfer-across-depth-cues" method was employed. Infants were habituated to a rotating object whose shape was specified by kinetic information and were then presented with stationary stereograms specifying the same object and a novel-shaped object. The disparity-sensitive infants looked significantly longer at the novel object than at the familiar object, whereas the disparity-insensitive infants showed no difference in looking time to the novel and the familiar objects. The results indicate that disparity-sensitive 4-month-old infants can perceive 3-dimensional-object shape from kinetic and binocular depth information.     

Prelinguistic Relational Concepts: Investigating Analogical Processing in Infants

This research asks whether analogical processing ability is present in human infants, using the simplest and most basic relation—the same–different relation. Experiment 1 (N = 26) tested whether 7‐ and 9‐month‐olds spontaneously detect and generalize these relations from a single example, as previous research has suggested. The attempted replication failed. Experiment 2 asked whether infants could abstract the relation via analogical processing (Experiment 2, N = 64). Indeed, with four exemplars, 7‐ and 9‐month‐olds could abstract the same–different relation and generalize it to novel pairs. Furthermore, prior experience with the objects disrupted learning. Facilitation from multiple exemplars and disruption by individual object salience are signatures of analogical learning. These results indicate that analogical ability is present by 7 months.     

熟悉而陌生——兼谈赵树理的成名原因

赵树理的小说文本从内容到形式都给人一种既熟悉又陌生的感觉,因＂熟悉＂而使人们喜闻乐见,因＂陌生＂又使人感到新鲜有趣。正是这种既熟悉又陌生的文本本身,使赵树理成为了具有划时代意义的著名作家。     

Children's sensitivity to intraword redundancy in spoken words.

Kindergarten, third-grade and fifth-grade children were tested on a same-different auditory discrimination task. Stimuli consisted of familiar and unfamiliar 3-letter words which were subdivided into high and low positional frequency word pairs. Analysis of correct same and different judgments supported the hypothesis that prereaders who have had normal language experiences develop sensitivities to intraword-redundancy relations. Children made significantly more correct same or different judgments when word pairs were high rather than low in summed positional frequency.     

Understanding Categorical Hierarchies: The Earliest Levels of Skill

2 categorization skills necessary for understanding hierarchies are the ability to form categories at different levels of generality and the ability to include the same objects into multiple categories. 2-year-olds appear to have the first skill, but some theoretical and empirical work suggests that the second may be a later acquisition. Yet, in 3 studies, 2- and 3-year-olds applied familiar basic level and superordinate labels to the same objects, even when reminded of basic labels before being tested with superordinates. They did not reserve superordinates for objects with unfamiliar basic level names (Study 2), and they were willing to apply superordinates to objects presented singly rather than in groups (Study 3). Thus, contrary to the implications of some previous work, 2- and 3-year-olds appear to have both of the categorization skills necessary for forming categorical hierarchies.     

Social interaction between drugged and undrugged rats

Social interaction between two rats placed in a hole-board apparatus was studied. The duration and frequency of active contact was higher for animals housed singly than for those housed in pairs, and for those tested with an unfamiliar rather than a familiar partner. Animals housed alone had a higher frequency and duration of passive contact, but the familiarity of the partner did not affect this measure. Chlorpromazine reduced the frequency of active contact but increased the frequency and duration of passive contact. When only one of the pair was drugged, both rats showed more frequent changes from one behavior to another, compared with pairs where both were in the same drug state. Animals housed alone showed the highest number of changes in behavior, and those tested with an unfamiliar partner showed a higher level than those tested with a familiar one.     

Young Children''s Disambiguation of Object Name Reference

Children show a disambiguation effect--a tendency to select unfamiliar rather than familiar things as the referents of new names. In previous studies, this effect has been reversed in young 2-year-olds, but not older children, by preexposing the unfamiliar objects, suggesting that attraction to novelty controls 2-years-olds' choices of referents for new names, but a mutual exclusivity and/or lexical gap-filling principle determines preschoolers' selections. Both the disambiguation effect and its reversal by preexposure were replicated in the present study; however, 24-month-olds' rate of selecting unfamiliar over familiar kinds was less when they were simply asked to choose between the items than when they were asked to identify the referents of unfamiliar names. Thus, some young children may have both an attraction to novel tokens and a tendency to honor an abstract lexical principle. Referent selections were also affected by object typicality and word similarity. Correlations between the tendency to acknowledge a new name's unfamiliarity and to treat it like a similar-sounding familiar name suggested that youngsters' phonological matching skills affect their interpretation of new names. Also, 4-year-olds who most often mapped distinctive-sounding new names to unfamiliar kinds tended to admit their unfamiliarity with these names most frequently, suggesting that children's increasing awareness of their own knowledge begins to affect their lexical processing during the preschool years.     

Diet sampling by wild Norway rats offered several unfamiliar foods

The present experiment was undertaken to examine directly the diet sampling behavior of wild Norway rats (Rattus norvegicus) faced with a choice among familiar and unfamiliar foods. First-generation, laboratory-reared wild Norway rats ate from four food cups. Three of the food cups were in unfamiliar locations and contained unfamiliar foods. The remaining food cup was in a familiar location and contained a familiar food. Subjects in a control group were offered the familiar food in all four locations. We found (1) that subjects in experimental and control conditions took equal amounts of time to first visit food cups in unfamiliar locations, (2) that subjects in the experimental condition (those with access to unfamiliar foods) ate at unfamiliar locations at a slower rate than did subjects in the control condition (those with access only to familiar food), (3) that subjects in the experimental condition were no more likely than subjects in the control condition to eat at one unfamiliar location at a time, and (4) that following a bout of eating at an unfamiliar food cup, subjects in the experimental condition waited no longer than subjects in the control condition before eating from a different unfamiliar food cup. We interpreted these data as indicating that although wild Norway rats are hesitant to eat unfamiliar foods, once they begin to eat such foods, they do not sample among them so as to facilitate identification of any toxin present.     

Following their companions as a form of exploration for human infants

Infants' following of other persons, often considered a measure of attachment, qualified as a form of exploration. The results of the first experiment indicated that following can be a means of investigating novel leaders: 16 9--12-month-old infants were as likely to follow an unfamiliar woman as they were the parent and were reliably more likely to follow a moving toy. The second and third experiments assessed the extent to which the experience of following familiar persons promotes learning about the environment. Infants who followed their mothers to 1 place were more likely later to investigate a similar place than those who initially either locomoted independently (experiment 2) or were transported by their mothers (experiment 3). The findings suggested that infants' transactions with the environment need not be considered antithetical to their social behavior.     

Developmental Changes in Infant Spatial Categorization: When More Is Best and When Less Is Enough

Two experiments examined infants' ability to form a spatial category when habituated to few (only 2) or many (6) exemplars of a spatial relation. Sixty‐four infants of 10 months and 64 infants of 14 months were habituated to dynamic events in which a toy was placed in a consistent spatial relation (in or on) to a referent object. At 10 months, infants formed a spatial category (looking longer at an unfamiliar than familiarized spatial relation) only when habituated to 6 exemplars. At 14 months, infants formed the spatial category regardless of the number of habituation exemplars. The results highlight developmental changes in infant spatial categorization and show that increasing exemplar number facilitates this ability in infants of 10 months.     

Toys and social interaction between infant peers

Claims that young infants fail to react in a social manner to one another and that toys preempt attention to peers were assessed by comparing the interactions observed between infant peers when they met in the presence of toys versus in their absence. 44 pairs of unacquainted infants (either 10--12 or 22--24 months of age) came with their mothers to an unfamiliar room. Without toys available in the room, infants of both ages more often contacted one another, smiled at and gestured to one another, and duplicated each other's actions. With toys, they showed and exchanged toys and spent more time synchronously manipulating similar play material. The results document that infants as young as 10 months of age are responsive to the person and behavior of an unfamiliar peer and that they are no less responsive than older infants to the social versus nonsocial aspects of a novel setting.