Biomedical subjects

D M Fragaszy

Publications and source records attributed to D M Fragaszy.

At least 19 recordsLinked to original sources

PubMed1999

Strategies used to combine seriated cups by chimpanzees (Pan troglodytes), bonobos (Pan paniscus), and capuchins (Cebus apella).

The authors investigated strategies used to combine seriated cups by apes (Pan troglodytes and P. paniscus) and monkeys (Cebus apella) using a protocol reported in P. M. Greenfield, K. Nelson, and E. Saltzman's (1972) study with children. It was hypothesized that apes would exhibit more hierarchical combinations of cups than monkeys, given apes' language capacity, and that apes would seriate the cups more efficiently than monkeys. As predicted, apes made many structures with the cups using a variety of strategies, and monkeys rarely combined the cups. After a training phase to orient monkeys to the task, the 2 genera did not differ in the strategies used to combine the cups or in efficiency in seriating the cups. Success in this task suggests that sensorimotor versions of hierarchically organized combinatorial activity are well within apes' and monkeys' abilities.

Animals↗

PubMed1999

Left hand preferences in capuchins (Cebus apella): role of spatial demands in manual activity.

Sixteen capuchins (Cebus apella) participated in four tasks that differed in their exploration demands and availability of visual cues. The two explorative tasks required the monkeys to discover sunflower seeds hidden in crevices in objects of various shapes, with vision (Haptic-Visual task) or without vision (Haptic task). Two other tasks required the capuchins to grasp sunflower seeds directly on a flat support, with vision (Visual reaching) or without vision (Tactual reaching). The presence or absence of exploration demands had a significant effect on the direction of hand preferences. The group displayed greater left hand preferences for the Haptic and Haptic-Visual tasks than for the two reaching tasks. The strength of manual preferences did not differ significantly among the four tasks. These findings suggest that the manipulo-spatial demands of a task are of particular importance for the expression of left hand bias in a population of capuchins. It is argued that left hand preferences for the haptic tasks may reflect a right hemisphere specialisation to integrate the spatial and motor components of action.

Journal Article↗

PubMed1998

Growth and reproduction in captive tufted capuchins (Cebus apella).

We present data on weight and reproduction from a colony of tufted capuchins monkeys (Cebus apella) over a 12 year period. The data constitute a normative record for this species. Weight at birth averages 210 g, and infants gain weight rapidly. Females typically first conceived just after their fifth birthday, and males were fertile by 4 years, 5 months. Interbirth intervals average 576 days. Eighty-seven percent of live-born infants survived past 6 months. Three of eight live-born infants that died prior to 6 months succumbed from trauma inflicted by cage mates.

Abortion, Veterinary↗

PubMed1997

Transfers of food from adults to infants in tufted capuchins (Cebus apella).

This study examined the behavioral mechanisms that support transfer of food from adults to infants in tufted capuchins (Cebus apella). Two captive groups of capuchins were presented with abundant quantities of unshelled pecans or commercial pellets. Five of 11 infant subjects could not open the nuts. A variety of tolerated interactions were initiated by infants toward adults, and food was frequently transferred. All such interactions were more frequent with nuts (a preferred food) than with pellets. Adult capuchins were equally tolerant of infant capuchins that could open nuts and those that could not. Tolerated interactions during feeding could result in acquisition of dietary information by young capuchins or to important, if intermittent, nutritional support.

Aging↗

PubMed1997

Developmental changes in manipulation in tufted capuchins (Cebus apella) from birth through 2 years and their relation to foraging and weaning.

This study examined the contributions of physical and sensorimotor development to manipulation in capuchins (Cebus apella) from birth to 2 years. Between months 1-6 and 7-12, manipulation increased significantly in frequency, in the proportion that was vigorous or required fine motor control, and in the proportion directed at portable objects. Fine motor control, moving objects in relation to the body, and stamina are largely in place by 12 months, after which little changed. All elements of the manipulative repertoire have appeared, and vigorous and dexterous activities have peaked before fully independent foraging. Emergence of permanent dentition and achievement of approximately half of adult body size accompany the attainment of fully independent foraging at 15 months. Thereafter, increasing strength and specific knowledge probably contribute more to changing foraging competence in young capuchins than do stamina and sensorimotor development.

Aging↗

PubMed1997

Manual exploratory procedures and asymmetries for a haptic search task: a comparison between capuchins (Cebus apella) and humans.

Left-hand preferences in monkeys (capuchins, macaques) for haptic discriminations have been taken to indicate that the right hemisphere is more involved than the left hemisphere in solving these tasks. We confirmed this left-hand bias in a group of 21 capuchins haptically searching for sunflower seeds located in crevices in 12 different objects (Lacreuse & Fragaszy, 1996). In an attempt to specify the relations of the left-hand bias to hand performance and hemispheric lateralisation, we analysed the manual exploratory procedures used by the subjects when exploring the objects, and compared them to those of humans confronted with the same task. All the hand-movement patterns displayed by humans were also observed in capuchins, but humans performed exhaustive explorations, whereas capuchins restricted their haptic investigations to limited portions of the objects. Both species adopted several ''exploratory procedures'' to investigate particular objects. Although capuchins showed a left-hand preference to perform the task, finer analyses of haptic exploratory procedures revealed no difference in the way the left and right hands explored the objects, nor in the efficiency with which each hand solved the task. Nor was any measurable difference in manual exploratory procedure and efficiency found in humans. The discussion emphasises the need to complement measures of manual preference with finer indices of hemispheric lateralisation, for a better understanding of functional asymmetries in primates.

Journal Article↗

PubMed1995

Performance in a tool-using task by common chimpanzees (Pan troglodytes), bonobos (Pan paniscus), an orangutan (Pongo pygmaeus), and capuchin monkeys (Cebus apella).

Performance by individual animals of three species of great apes (Pan troglodytes, Pan paniscus, and Pongo pygmaeus) and capuchin monkeys (Cebus apella) was assessed by presenting a food treat inside a clear tube. The subjects readily used a straight stick to obtain the food. When sticks were bundled together, the apes immediately unwrapped the bundle to obtain an individual stick, whereas capuchins attempted to insert the bundled sticks. When a misshapen stick was provided, apes, but not capuchins, showed an improvement in terms of modifying the misshapen stick before insertion. Our results indicate that all these species can solve these tasks. However, only the performance of apes is consistent with emerging comprehension of the causal relations required for the avoidance of errors in the more complex tasks.

Animals↗

PubMed1994

Development of manipulation in capuchin monkeys during the first 6 months.

This study describes the orderly changes in manipulation over the first 6 months in capuchin monkeys (Cebus apella). By 6 months of age, all the basic forms of manipulation seen in adults have appeared. Actions that occur frequently in the first 8 weeks are gentle and involve sustained visual orientation and aimed reaching. Later actions are more vigorous, and involve grasping. Large increases in the rate of activity are evident over the period of development studied. The increase from the first 8 weeks to the second may be due to (a) an increase in the amount of time spent alert and active, (b) a decrease in the amount of time spent in a ventral position, (c) improvements in postural control and stamina and (d) the onset of independent locomotion. Changes in form can be attributed primarily to postural factors and to neuromuscular development (precisely aimed and controlled movements appearing in the 5th and 6th months).

Aging↗

PubMed1991

Behavioral development and maternal care in tufted capuchins (Cebus apella) and squirrel monkeys (Saimiri sciureus) from birth through seven months.

Fourteen infant capuchins and eight squirrel monkeys reared by their mothers in captive species-typical social groups were observed from birth through 7 months. Motoric altriciality of the neonatal capuchin relative to the squirrel monkey is a key feature of behavioral differences between the species in the first few months after birth. Infants of the two species differed substantially in age at onset of independent locomotion, the developmental profile of independent activities, and the overall amount and rate of particular social activities. Capuchins displayed a lag of 7 weeks relative to squirrel monkeys in the pattern of increasing time spent alone; lags in other indices of independent activity and exploratory behaviors were also evident, although not as clear-cut. The species also differed substantially in the nature and frequency of social interactions between infants and others. Capuchins, especially later-born infants of multiparous mothers, experienced a more socially interactive infancy than squirrel monkeys. Contrasts in behavioral developmental and infant care in the two species are related to the timing and duration of the weaning process.

Age Factors↗

PubMed1991

Generative aspects of manipulation in tufted capuchin monkeys (Cebus apella).

Evaluating the cognitive and ontogenetic bases of tool use in primates requires comparative data on the generative nature of manipulation, including the frequency and variety of combinations of actions and objects. Thirty-one tufted capuchins (Cebus apella) of 3 age groups devoted significant proportions of time to interaction with objects and substrates. Activity that combined an object with a substrate occurred often; activities that combined 2 portable objects were less frequent. Predictions drawn from neo-Piagetian theory of an ontogenetic link between combinatorial behaviors and the onset of tool use were not supported. The frequency and generative nature of capuchins' manipulative activity, particularly acts combining objects and substrates, could account for their proclivity to use tools. The use of tools by capuchins need not involve the representational abilities proposed by neo-Piagetian theory.

Age Factors↗

PubMed1990

Hand preference and performance on unimanual and bimanual tasks in capuchin monkeys (Cebus apella).

Patterns of manual preference and the extent to which preference provided a benefit in performance (movement time) were evaluated in 7 young adult capuchin monkeys (Cebus apella). Directions of preference were inconsistent within individual animals across home-cage activities, unimanual, and bimanual experimental tasks. Preferences were more strongly expressed in the experimental tasks than in the home cage. A left bias in the population for prehension, predicted by recent theories, was not evident in any setting. Movement time was moderately negatively correlated with degree of preference within experimental tasks. The benefit to performance conferred by lateral preference was not dependent on whether the right or left hand was preferred. Lateralization of prehension appears to be a flexible process in these monkeys, which can result in quickly realized benefits in some conditions.

Animals↗

PubMed1990

Variability and adaptability in the genus Cebus.

Capuchins (Cebus) present an array of similarities to humans and apes in morphology, behavior and life history which raise a host of questions about the relations of these features to each other and about their evolutionary origins. As a genus and as individuals, capuchins possess marked adaptability and great variability in behavior. These two characteristics contribute directly to the biological success of capuchins. Variability and adaptability are also hallmarks of human behavior.

Animals↗

PubMed1990

Early behavioral development in capuchins (Cebus).

Capuchin infants (genus Cebus) are born in a behaviorally more altricial state than is known for infants of other primate taxa except apes. Development in the first 2 months after birth is characterized by the major reorganization of sleeping and waking, assumption of postural control and the appearance of prehension. Capuchins develop postural control, prehension and locomotion later than do squirrel monkeys, baboons or macaques, presenting a pattern of motor development intermediate between these relatively more precocial genera and apes. Capuchins provide a useful model primate system in which to study development and its links with behavioral variability and life history.

Animals↗

PubMed1990

Social processes affecting the appearance of innovative behaviors in capuchin monkeys.

We consider the role of social factors in the appearance of innovative problem-solving behaviors in capuchins. Processes supporting dissemination of innovative behaviors included social enhancement of interest in the objects and area around the task and (rarely) coaction. Factors inhibiting display of innovative behaviors included restricted access and requirements for social vigilance among animals of vulnerable social status and exploitation by noninnovators of others' behaviors. We urge caution in interpreting the increased appearance of novel behaviors in primates as evidence for imitation or facilitation and call for a more rigorous experimental investigation of social learning in primates.

Animals↗

PubMed1989

Activity states and motor activity in an infant capuchin monkey (Cebus apella) from birth through eleven weeks.

Behavioral states and motor activity of an infant capuchin monkey reared by its mother in a social group were studied for 11 weeks after birth. Manipulative activity was infrequent through the first four weeks after birth; what little occurred was mediated by other animals interacting with the infant. The rate of manipulation increased the most between weeks 8 and 9. At the same time, the most frequent targets of manipulation shifted from the infant's own body and the bodies of others to surfaces and inanimate objects in the cage. Large increases in the proportion of time in an Alert/active state and improvement in postural control also occurred at the end of the second month. The data suggest that major organizational changes in motor coordination and the regulation of behavioral state occurred jointly over a short period of time at about 8 weeks of age. In comparison to other species of monkeys, the capuchin infant displayed later development of manipulation, postural control, and independent locomotion, and greater dependence on social contacts for early interaction with its environment. These characteristics are in accord with the greater neurological immaturity of the capuchin infant at birth compared to other monkeys.

Aging↗

PubMed1989

Social influences on the acquisition of tool-using behaviors in tufted capuchin monkeys (Cebus apella).

To identify behaviors related to acquisition of tool-use in tufted capuchins (Cebus apella), we presented two tool-using tasks to two groups, extending findings by Westergaard and Fragaszy (1987) and Visalberghi (in press). Five Ss learned to use the tools in each task. The primary predictor of success was level of interest in the task. Observation of others at the apparatus did not facilitate exploratory behaviors or contact with the tools in the observers. Most animals performed exploratory behaviors more often when they were at the apparatus alone than when with another, whether or not the other was using a tool. Observers were quick to learn the relationship between another's activities and the appearance of food. We conclude that capuchins do not readily learn about instrumental relations by observation of others or imitate other's acts. Imitation probably plays no role in the spread of novel instrumental behaviors among monkeys.

Animals↗

PubMed1986

Comparative studies of squirrel monkeys (Saimiri sciureus) and titi monkeys (Callicebus moloch): performance on choice tasks in near space.

Squirrel monkeys (Saimiri sciureus) and titi monkeys (Callicebus moloch) were studied in tasks involving reaching for food in near space (arm's reach). Although performance by monkeys of the two species differed in several ways familiar from previous studies, the species did not differ in the tendency to adopt a habitual position or limb during reaching. The findings contrast with previous work on spatial preferences in these species in tasks involving movement of the whole body. Together with the results of previous studies on movement patterns in these two species, the findings are placed in a comparative psychological framework of the proximate sources of use of space in nature.

Animals↗

PubMed1983

Preliminary quantitative studies of prehension in squirrel monkeys (Saimiri sciureus).

Squirrel monkeys were filmed in the act of prehending objects of various sizes, shapes, and states of motion. Subsequent three-dimensional analyses indicated that general aspects of prehension do not vary grossly across individuals nor as a function of the object to be prehended, at least at the level of measurement used in these studies. The monkeys exhibited only whole-hand control, even with small or moving objects. However, in comparison with stationary objects, moving objects did elicit variations of arm and hand positions, and were associated with higher frequencies of blinking than nonmoving objects. Some stationary objects also elicited subtle adjustments of movement and form. Sex differences were found in several aspects of prehensive movement and passive joint mobility, but the significance of these findings is not yet clear.

Animals↗