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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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 the 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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experience and Materials Affect Combinatorial Construction in Tufted Capuchin Monkeys (Cebus apella).

Three movement procedures can combine nesting cups into seriated structures. Reliance on these procedures changes with age in human children, and the putatively most advanced emerges as a predominant procedure at 3 or more years. Six monkeys' (Cebus apella) combinatorial procedures and successes at nesting seriated cups were evaluated. The current study examined whether the procedures used (a) shift toward more efficient procedures after unguided experience, (b) are dependent on the type of object being combined, and (c) can be altered by specific training history. All factors produced a change in procedure for some individuals, suggesting that combinatorial procedure is a product of the dynamic influences of preexisting tendencies to act in certain ways, of environmental circumstances, and of prior experiences. Some monkeys preferred the putatively most cognitively complex procedure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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

In 2 experiments, 12 adult squirrel monkeys and 10 adult titi monkeys were studied in tasks involving reaching for food in near space (arm's reach). Although performance by Ss of the 2 species differed in several ways consistent with 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 2 species, the present findings are placed in a comparative psychological framework of the proximate sources of use of space in nature. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The manufacture and use of tools by capuchin monkeys (Cebus apella).

In this report we describe the manufacture and use of tools in captive groups of tufted capuchin monkeys (Cebus apella). Apparatus designed to accommodate probing and sponging behaviors were introduced into the monkeys' home cage with materials provided for fashioning tools. In one group of 9 capuchins, 6 were successful in manufacturing and using probes, and in a second group, 4 of 5 capuchins were successful in using probes, and 3 in manufacturing them. In a follow-up study with the larger group of capuchins, 8 monkeys were successful in manufacturing sponging tools from paper towels. Our studies provide the first report of spontaneous manufacture of tools in any group of monkeys. The tool-using and manufacturing behaviors observed in the capuchins were similar in form, function, and ontogeny to those that have previously been reported for chimpanzees. Our results provide further evidence that capuchins possess extensive manipulative propensities and emphasize the significance of the normal social environment in the full expression of these propensities. Finally, we spell out some directions future research could take in developing an understanding of the psychological characteristics underlying tool-related behaviors in diverse species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Choosing and Using Tools: Capuchins (Cebus apella) Use a Different Metric Than Tamarins (Saguinus oedipus).

Cotton-top tamarins (Saguinus oedipus) selected canes positioned so that a straight inward pull brought food within reach (M. D. Hauser, 1997; see also record 1997-41347-003). Tamarins failed to retrieve food with canes in other positions, and they did not reposition these canes. In this study, tufted capuchin monkeys (Cebus apella) preferred canes they could pull straight in when these were present, but they also repositioned canes in individually variable ways, and their success at obtaining food with repositioned canes improved with practice. In accord with predictions drawn from ecological psychology, capuchins discovered affordances of canes through exploratory actions with these objects, whereas tamarins did not. Ecological theory predicts these differences on the basis of species-typical manipulative activity, and it provides a useful approach for the study of species differences in tool-using behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of skilled detection and extraction of embedded prey by wild brown capuchin monkeys (cebus apella apella).

Brown capuchin monkeys (Cebus apella apella) in Suriname forage on larvae enclosed within healthy bamboo stalks. We applied the searching versus handling dichotomy of optimal foraging models to highlight developmental processes contributing to foraging on embedded prey. Larvae acquisition begins with search; selecting an appropriate stalk and locating the embedded larvae; followed by handling, ripping the stalk open, and extracting the larvae. Although extraction behaviors were present at low rates in infant capuchins' repertoire, we found that the acquisition of adequate detection techniques was fully completed in subadults, aged around 6. Selecting appropriate foraging substrates, requiring accurate assessment of the physical properties of bamboo stalks, gradually increased with age and experience. We showed that both components of searching required extended practice beyond that required to master the handling components. We conclude that the developmental sequence of skill acquisition goes counter to the preceding logical sequence of foraging process and suggest that searching components present greater challenges than handling components in extractive foraging. Specifying the searching components of foraging more precisely will enhance understanding of species variation in the developmental schedule of foraging skills. (PsycINFO Database Record (c) 2010 APA, all rights reserved)