Search PubMed⌕ Search

Biomedical subjects

M Tomasello

Publications and source records attributed to M Tomasello.

33 records · Page 2Linked to original sources
PubMed1993

Processes of social learning in the tool use of chimpanzees (Pan troglodytes) and human children (Homo sapiens).

Common chimpanzees (Pan troglodytes) and 2-year-old human children (Homo sapiens) were presented with a rakelike tool and a desirable but out-of-reach object. One group of subjects observed a human demonstrator use the tool in one way, and another group observed a demonstrator use the tool in another way. Children in both cases did what the model did. Chimpanzee subjects, however, behaved identically in the 2 model conditions. Both groups performed better than subjects who saw no demonstration. This pattern of results suggest that the chimpanzees were paying attention to the general functional relations in the task and to the results obtained by the demonstrator but not to the actual methods of tool use demonstrated. Human children were focused on the demonstrator's actual methods of tool use (her behavior). The different social learning processes used by the 2 species have implications for their different forms of social organization.

Animals↗
PubMed1993

Imitative learning of actions on objects by children, chimpanzees, and enculturated chimpanzees.

In this study we compared the abilities of chimpanzees and human children to imitatively learn novel actions on objects. Of particular interest were possible differences between chimpanzees raised mostly with conspecifics (mother-reared) and chimpanzees raised in a human-like cultural environment (enculturated). Subjects were thus 3 enculturated and 3 mother-reared chimpanzees, along with 8 18-month-old and 8 30-month-old human children. Each subject was tested over a 2-day period with 16 novel objects. The introduction of each object was preceded by a baseline period in which the subject's natural proclivities toward the object were determined. For 12 objects, a human experimenter demonstrated first a simple and then a complex novel action, instructing the subject in each case to "Do what I do" (chimpanzees were prepared for the task behaviorally as well). For the other 4 objects, demonstration of a single action took place on the first day and the subject's opportunity to imitate was delayed until the second day, 48 hours later. Actions that a subject produced in baseline were excluded from further analysis. For each analyzed action, the subject's behavior was scored as to whether it successfully reproduced (1) the end result of the demonstrated action, and (2) the behavioral means used by the demonstrator. Results showed that in immediate imitation the mother-reared chimpanzees were much poorer imitators than the enculturated chimpanzees and the human children, who did not differ from one another. Surprisingly, on the delay trials, the enculturated chimpanzees significantly outperformed the other 3 groups. We conclude from these results that a human-like sociocultural environment is an essential component in the development of human-like social-cognitive and imitative learning skills for chimpanzees, and perhaps for human beings as well.

Animals↗
PubMed1992

Joint attention on actions: acquiring verbs in ostensive and non-ostensive contexts.

Two studies of verb learning are reported. The focus of both studies was on children in their second year of life learning verbs in various pragmatic contexts. Of particular interest was the comparison of ostensive contexts--in which word and referent were simultaneously present in the child's perceptual field--to non-ostensive contexts. In a naturalistic study of 24 children at 1;3 and 1;9, it was found that mothers modelled verbs for their children most often BEFORE the referent action actually occurred. Over 60% of maternal verbs were used to refer to actions that mothers wished children to perform or that they were anticipating their performing (IMPENDING actions). Some verbs were also used to refer to current actions (ONGOING actions) or actions that had just been completed (COMPLETED actions). Children responded with comprehension most often to impending models. Impending and completed models, but not ongoing models, were correlated with children's verb vocabularies at 1;9. The second study was a lexical training study of 48 two-year-olds. Children learned to produce a novel verb best when it was modelled in the impending condition. They learned to comprehend it equally well in the impending and completed conditions. Children showed no signs of superior learning in the ostensive (ongoing) learning context. Results of the two studies are discussed in terms of the different learning processes involved in acquiring nouns and verbs, and, more broadly, in terms of a social-pragmatic view of language acquisition in which the ostensive teaching paradigm is but one of many contexts in which children learn to establish a joint attentional focus with mature language users.

Child Language↗
PubMed1990

Young children's conversations with their mothers and fathers: differences in breakdown and repair.

In this study we compared the conversations of mothers and fathers with their children at 1; 3 and 1; 9, with special attention to breakdown-repair sequences. We found that, overall, children and secondary caregiver fathers experienced more communicative breakdowns than did children and primary caregiver mothers. More specifically, fathers requested clarification of their children more often than did mothers, and they most often used a non-specific query (e.g. What?). Mothers used more specific queries (e.g. Put it where?) and were involved in more 'looped' sequences involving multiple requests for clarification. Fathers also failed to acknowledge child utterances more often than did mothers. After a father non-acknowledgement, children tended not to persist and when they did they often received further non-acknowledgements; the dyad did not often return to the child's original topic. After a maternal non-acknowledgement, on the other hand, children persisted and the dyad more often returned to its previous topic. The results are interpreted as support for the Bridge Hypothesis which claims that fathers present children with communicative challenges that help prepare them for communication with less familiar adults.

Communication↗
PubMed1990

Peer interaction in infant chimpanzees.

The peer interactions of 6 infant chimpanzees (Pan troglodytes) ranging in age from 18 to 50 months were observed in a seminatural context. The infants and their mothers lived as members of a captive social group at the Yerkes Regional Primate Research Center. An analysis of contact initiations between infants indicated that the most preferred peer interactant was the youngest and the least preferred was the oldest infant. Infants also initiated more interactions with the offspring of adults that had the closest relationships with both themselves and their mothers. These results indicate that a number of factors may influence the peer affiliations of infant chimpanzees, including the age of the infant and the mother's social relationships.

Age Factors↗
PubMed1986

Evidence for social referencing in young chimpanzees (Pan troglodytes).

A captive chimpanzee group was observed in order to determine the extent to which the social interactions of the infants and juveniles (18-50 months) were affected by their mothers' relationships with other adult group members. It was found that the young chimpanzees initiated more interactions with adults who interacted more with their mothers. A vast majority of those interactions occurred at significant distances from the mother. It is argued that these data imply a social-cognitive ability in young chimpanzees closely related to the human infant's ability to use its mother in 'social referencing'.

Animals↗
PubMed1986

Joint attention and early language.

This paper reports 2 studies that explore the role of joint attentional processes in the child's acquisition of language. In the first study, 24 children were videotaped at 15 and 21 months of age in naturalistic interaction with their mothers. Episodes of joint attentional focus between mother and child--for example, joint play with an object--were identified. Inside, as opposed to outside, these episodes both mothers and children produced more utterances, mothers used shorter sentences and more comments, and dyads engaged in longer conversations. Inside joint episodes maternal references to objects that were already the child's focus of attention were positively correlated with the child's vocabulary at 21 months, while object references that attempted to redirect the child's attention were negatively correlated. No measures from outside these episodes related to child language. In an experimental study, an adult attempted to teach novel words to 10 17-month-old children. Words referring to objects on which the child's attention was already focused were learned better than words presented in an attempt to redirect the child's attentional focus.

Attention↗
PubMed1984

Children's speech revisions for a familiar and an unfamiliar adult.

Initial characterizations of the communicative abilities of preschoolers stressed their egocentric nature. Recently, however, even 2-year-olds have been observed to adjust their speech appropriately in situations in which the listener provides feedback by signaling noncomprehension. The current study had an adult signal noncomprehension to the requests of 2-year-old Stage I and Stage II children. Each child interacted with a familiar (mother) and an unfamiliar adult. The children repeated their requests about one third of the time and revised them about two thirds of the time. Stage I children elaborated their requests significantly more often than Stage II children. The familiarity of the adult listener had no effect on the way Stage II children revised their requests, but the Stage I children's revisions contained novel lexical items more often when they were interacting with the unfamiliar adult. Both of these findings may have resulted from the fact that the more conversationally skilled Stage II children relied on verbal-conversational cues, which were the same for both adult interactants in this situation. The Stage I children may have been less aware of these conversational cues, relying on general social cues such as familiarity of the interactant. The results are discussed in terms of the potential role of different types of adults in the language acquisition process.

Adult↗
PubMedDate not supplied

A nonverbal false belief task: the performance of children and great apes.

A nonverbal task of false belief understanding was given to 4- and 5-year-old children (N = 28) and to two species of great ape: chimpanzees and orangutans (N = 7). The task was embedded in a series of finding games in which an adult (the hider) hid a reward in one of two identical containers, and another adult (the communicator) observed the hiding process and attempted to help the participant by placing a marker on the container that she believed to hold the reward. An initial series of control trials ensured that participants were able to use the marker to locate the reward, follow the reward in both visible and invisible displacements, and ignore the marker when they knew it to be incorrect. In the crucial false belief trials, the communicator watched the hiding process and then left the area, at which time the hider switched the locations of the containers. When the communicator returned, she marked the container at the location where she had seen the reward hidden, which was incorrect. The hider then gave the subject the opportunity to find the sticker. Successful performance required participants to reason as follows: the communicator placed the marker where she saw the reward hidden; the container that was at that location is now at the other location; so the reward is at the other location. Children were also given a verbal false belief task in the context of this same hiding game. The two main results of the study were: (1) children's performance on the verbal and nonverbal false belief tasks were highly correlated (and both fit very closely with age norms from previous studies), and (2) no ape succeeded in the nonverbal false belief task even though they succeeded in all of the control trials indicating mastery of the general task demands.

Analysis of Variance↗
PubMedDate not supplied

Young children's overgeneralizations with fixed transitivity verbs.

The present study examined English-speaking children's tendency to make argument structure overgeneralization errors (e.g., I disappeared it). Children were exposed to several English verbs of fixed transitivity (exclusively intransitive or exclusively transitive) and then asked questions that encouraged them to overgeneralize usage of the verbs. Seventy-two children (24 in each of three age groups: 3, 4/5, and 8 years of age) experienced four actions performed by puppets. Each action had two verbs of similar meaning associated with it in the context of the experimental action: one more familiar to young children and one less familiar. Children at all ages were more likely to overgeneralize usage of verbs that were less familiar to them, supporting the hypothesis that children's usage of verbs in particular construction types becomes entrenched over time. As children solidly learn the transitivity status of particular verbs, they become more reluctant to use those verbs in other argument structure constructions.

Child↗