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Biomedical subjects

E Visalberghi

Publications and source records attributed to E Visalberghi.

At least 19 recordsLinked to original sources
PubMed2007

Characteristics of hammer stones and anvils used by wild bearded capuchin monkeys (Cebus libidinosus) to crack open palm nuts.

Capuchins living in Boa Vista (Piauì, Brazil) crack open hard palm nuts on hard, level surfaces (anvils) using stones (hammers) as percussive tools. This activity leaves diagnostic physical remains: distinctive shallow depressions (pits) on the surface of the anvil, cracked shells, and stone hammers on the anvil. To initiate comparison of percussive stone tool use and interpretation of the artifacts it produces across capuchins, chimpanzees, and hominins, we describe a sample of the anvils and hammer stones used by capuchin monkeys at our site. Anvils (boulders and logs) were located predominantly in the transition zone between the flat open woodland and ridges, in locations that offered some overhead coverage, and with a tree nearby, but not necessarily near palm trees. Anvils contained shallow, hemispherical pits with smooth interiors. Hammers represent a diverse assemblage of ancient rocks that are much harder than the prevailing sedimentary rock out of which they eroded. Hard stones large enough to serve as hammers were more abundant on the anvils than in the surrounding area, indicating that capuchins transport them to the anvils. Capuchins use hammers weighing on average more than 1 kg, a weight that is equivalent to 25-40% of the average body weight for adult males and females. Our findings indicate that capuchins select stones to use as hammers and transport stones and nuts to anvil sites. Wild capuchins provide a new reference point for interpreting early percussive stone tool use in hominins, and a point of comparison with chimpanzees cracking nuts.

Animals↗
PubMed2005

The observation and hearing of eating actions activates motor programs related to eating in macaque monkeys.

The observation of actions can lead, in some cases, to the repetition of those same actions. In other words, motor programs similar to those observed can be recruited. Since this phenomenon is expressed when in the presence of another individual, it has been named social facilitation. In the present study we investigated whether the observation and/or hearing of eating actions facilitate eating behaviors in observing/listening pig-tailed macaques. In experiment 1, the observation of an eating room mate significantly enhanced eating behavior in the observer. Similar results were obtained (experiment 2) in response to the sound of eating actions but not to control sounds (experiment 3). We propose that eating facilitation triggered by observation or listening of eating actions can rely on the mirror neuron system of ventral premotor cortex that provides a matching between the observed/listened action and the executed action. This matching system can subsequently trigger the motor programs necessary for repeating the observed/heard actions.

Acoustic Stimulation↗
PubMed2004

Socially biased learning in monkeys.

We review socially biased learning about food and problem solving in monkeys, relying especially on studies with tufted capuchin monkeys (Cebus apella) and callitrichid monkeys. Capuchin monkeys most effectively learn to solve a new problem when they can act jointly with an experienced partner in a socially tolerant setting and when the problem can be solved by direct action on an object or substrate, but they do not learn by imitation. Capuchin monkeys are motivated to eat foods, whether familiar or novel, when they are with others that are eating, regardless of what the others are eating. Thus, social bias in learning about foods is indirect and mediated by facilitation of feeding. In most respects, social biases in learning are similar in capuchins and callitrichids, except that callitrichids provide more specific behavioral cues to others about the availability and palatability of foods. Callitrichids generally are more tolerant toward group members and coordinate their activity in space and time more closely than capuchins do. These characteristics support stronger social biases in learning in callitrichids than in capuchins in some situations. On the other hand, callitrichids' more limited range of manipulative behaviors, greater neophobia, and greater sensitivity to the risk of predation restricts what these monkeys learn in comparison with capuchins. We suggest that socially biased learning is always the collective outcome of interacting physical, social, and individual factors, and that differences across populations and species in social bias in learning reflect variations in all these dimensions. Progress in understanding socially biased learning in nonhuman species will be aided by the development of appropriately detailed models of the richly interconnected processes affecting learning.

Adaptation, Psychological↗
PubMed2000

Response to changes in food palatability in tufted capuchin monkeys, Cebus apella.

Palatability of plant foods may change over time in relation to the concentration of toxic secondary metabolites. We investigated the behavioural response of capuchin monkeys to this type of change and assessed the influence of social conditions. Twenty-seven tufted capuchin monkeys were presented in Social or Individual conditions with a familiar palatable food (phase 1), with the same familiar food to which pepper had been added, making it unpalatable (phase 2), and with the same familiar palatable food of phase 1 (phase 3). Five sessions were carried out in each phase. The capuchins adapted quickly to the change in food palatability by reducing (phase 2) and increasing (phase 3) the amounts of food eaten. The unpalatable food prompted an increase in olfactory exploration and in food processing. The experimental conditions (Social versus Individual) did not influence consumption, or any of the other behaviours. In addition, capuchins were more often near subjects with food in phases 2 and 3 in which palatability changed than in phase 1. These findings show that capuchins readily adjust to changes in flavour and palatability of a familiar food and that sudden unpalatability has no carry-over effects. Therefore, capuchins behave differently towards a familiar food whose palatability has changed than they do towards novel foods. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2000

Seeing group members eating a familiar food enhances the acceptance of novel foods in capuchin monkeys.

In primates, social context is one of the factors that increases the acceptance of novel foods. Previous experiments showed that tufted capuchins, Cebus apella, eat significantly more of novel foods when in the presence of group members eating the same novel foods. Several processes may have led to these results. The mere presence of group members may reduce the individual's stress of being alone, or its neophobic response and, consequently, may increase its food consumption. The individual may be influenced by what group members do, and local/stimulus enhancement and/or social facilitation may occur. To investigate the above processes, we assessed whether an individual capuchin monkey's consumption of novel foods is lower when (1) the individual is alone with nobody in the nearby cage than when (2) group members are present in the nearby cage with no food or when (3) they are present and eating a familiar food. We tested 15 subjects with three novel foods, each presented in one condition. In both social conditions, the more group members there were by the food box the more the experimental subject ate. In addition, when group members were present and eating food, there was a significant increase in the acceptance of the three foods, regardless of what group members were eating. We argue that social facilitation of eating is a quicker way to overcome neophobia and only social facilitation of eating what the others are eating can be considered a safe way to learn about a safe diet. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2000

Learning to cope with two different food distributions: the performance of house mice (Mus musculus domesticus).

Search abilities of mice (Mus musculus domesticus) were evaluated using an arena closed by a ceiling in which 9 food sources (which mice could reach standing on their hind legs) could be arranged according to 2 configurations: a 3 x 3 square matrix and 3 clusters each containing 3 food sources. Testing conditions prevented olfactory and visual cues from being left after visits to food sources, and mice were able to choose alternative routes between food sources. Results showed that mice were more efficient with the matrix than with the cluster configuration. Sex differences were observed: Females improved their performance with both configurations, whereas males improved only with the matrix one. Mice did not develop evident search strategies that would minimize task complexity. Comparison with data published on capuchin monkeys revealed differences, with monkeys performing better with the cluster configuration than with the matrix and applying searching strategies.

Animals↗
PubMed1999

Display of proceptive behaviors in relation to urinary and fecal progestin levels over the ovarian cycle in female tufted capuchin monkeys.

In many primates species, female sexual attractivity is influenced by behavioral cues as well as by nonbehavioral cues (i.e., visual-morphological or chemical signals). Both kinds of cues are usually related to the ovarian cycle and female hormonal state. Female tufted capuchins (Cebus apella) lack any external morphological change in relation to the ovarian cycle and evidence of scent-marking behavior has never been reported. In addition, tufted capuchin males do not routinely investigate the female's body or urine. Instead, capuchin females are extremely active in sexually soliciting the male(s) and their courtship toward them involves a rich behavioral repertoire. In the present study we defined female tufted capuchin proceptivity and investigated its relationship with female reproductive state. Ovarian hormones were measured in urine and fecal samples from four captive females in order to (a) assess their reliability for monitoring female ovarian function and (b) provide information on the timing of the component cycle phases and in particular the periovulatory phase. Measurements of urinary and fecal progestin metabolites provided the best indicator of ovarian cyclicity and for timing of the periovulatory phase. Through a multivariate analysis of the behavioral data set we distinguished four behaviors (eyebrow raising with vocalization, touching-and-running, nuzzling and head cocking) which showed a marked cyclicity (21.3 days) that matched that of urinary progesterone (21.9 days). Data showed that each period of proceptive behaviors was 2.7 +/- 0.8 days long and the day of a defined luteal phase rise in urinary progesterone levels was markedly shifted toward the end of this period. Furthermore, the ejaculations observed always occurred within proceptive periods. The results clearly indicate that female behavior is a good indicator of the periovulatory phase and can enhance female attractivity.

Animals↗
PubMed1998

Social context and consumption of unfamiliar foods by capuchin monkeys (Cebus apella) over repeated encounters.

Visalberghi and Fragaszy [Animal Behaviour 49:1089-1095, 1995] have shown that social influences affect acceptance of novel foods. However, little is known about the temporal course on which such influences act (e.g., for how long they persist and for how many encounters they are effective). To explore this issue, 11 adult tufted capuchins were observed during ten successive encounters with eight unfamiliar foods (phase 1, in which subjects were tested in social or individual condition) and ten more encounters 6 months later (phase 2, in which all subjects were tested in social condition). A total of 680 observational sessions were carried out. Results show that during the first five encounters in phase 1, capuchins ate more when they encountered these foods in the presence of their groupmates than if they encountered them alone. Thereafter, during the second five encounters of phase 1, foods were consumed equivalently whether presented to monkeys socially or individually. In phase 2, the foods were consumed equivalently regardless of the previous circumstance of their presentation (social or alone). In phase 2, consumption was similar to that scored in a previous study for familiar foods [Visalberghi & Fragaszy, Animal Behaviour 49:1089-1095, 1995]. We conclude that 1) foods remain unfamiliar to capuchins only for the first few encounters, 2) social facilitation of consumption of unfamiliar foods is of limited duration, and 3) individuals consumed equivalent amounts of an unfamiliar food when they repeatedly encountered it alone or in the presence of groupmates. These results caution those who interpret similar feeding habits in primate groups as evidence of social influences.

Animals↗
PubMed1997

Infant tufted capuchin monkeys' behaviour with novel foods: opportunism, not selectivity

To determine whether young capuchin monkeys, Cebus apellaselectively interacted with others concerning novel foods, 11 infants (4.5-12 months) living in two groups were observed following presentation of familiar or novel foods. Foods were presented either to the whole group or to infants in a section of the home cage to which only they had access. Infants showed more frequent interest in others' food and picked up foods more frequently when foods were novel, and they tended to eat novel foods more frequently than familiar foods. The pattern was the same whether the foods were presented to the group or only to infants. Infants expressed interest in others' novel foods equally often before and after sampling these foods themselves. The frequency of interest in others' food correlated positively with age. It is concluded that acceptance of novel foods in these monkeys occurs readily regardless of socially provided information about edibility. Social interactions do not appear to make important contributions to acceptance of novel foods by infant capuchin monkeys.

Journal Article↗
PubMed1997

Capuchin monkeys, Cebus apella fail to understand a cooperative task

We investigated whether capuchin monkeys cooperate to solve a task and to what extent they take into account the behaviour of another individual when cooperating. Two groups of capuchin monkeys (N=5 and 6) were tested in a task whose solution required simultaneous pulling of two handles which were too far from one another to be pulled by one monkey. Before carrying out the cooperation study, individual monkeys were trained to pull one handle (training phase 1) and to pull two handles simultaneously (training phase 2) for a food reward. Nine subjects were successful in training phase 1, and five in training phase 2. In the cooperation study seven subjects were successful, that is, pulled one handle while a companion pulled the other. Further analyses revealed that capuchins did not increase their pulling actions when a partner was close to or at the other handle, that is, when cooperation might occur. These data suggest that capuchin monkeys acted together at the task and got the reward without understanding the role of the partner and without taking its behaviour into consideration. Social tolerance, as well as their tendency to explore and their manual dexterity, were the major factors accounting for the capuchins' success.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour

Journal Article↗
PubMed1995

Comprehension of cause-effect relations in a tool-using task by chimpanzees (Pan troglodytes).

Five chimpanzees (Pan troglodytes) were tested to assess their understanding of causality in a tool task. The task consisted of a transparent tube with a trap-hole drilled in its middle. A reward was randomly placed on either side of the hole. Depending on which side the chimpanzee inserted the stick into, the candy was either pushed out of the tube or into the trap. In Experiment 1, the success rate of 2 chimpanzees rose highly above chance, but that of the other subjects did not. Results show that the 2 successful chimpanzees selected the correct side for insertion beforehand. Experiment 2 ruled out the possibility that their success was due to a distance-based associative rule, and the results favor an alternative hypothesis that relates success to an understanding of the causal relation between the tool-using action and its outcome.

Animals↗
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

Lack of comprehension of cause-effect relations in tool-using capuchin monkeys (Cebus apella).

Four tufted capuchin monkeys (Cebus apella), successful in a tool task in which they used a stick to push a reward out of a tube, were tested in a similar task, with a tube with a hole and a small trap. Depending on where the stick was inserted, the reward was pushed either out of the tube or into the trap. With the trap-tube task, we assessed whether the monkeys understood the cause-effect relation between their behavior and the outcome. In Experiment 1, each subject underwent 14 10-trial blocks with the trap tube. Three subjects performed at chance level. The 4th subject's (Rb) performance improved, reaching 95% success in the last 6 blocks. In Experiment 2, Rb received additional tests to investigate its successful strategy further. Rb solved the trap-tube task by means of a distance-based, associative rule. The performances of the 4 subjects indicate that they did not take into account the effects of their actions on the reward.

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

Tool use in Cebus.

This paper summarizes early anecdotal information and systematic studies of tool use in capuchin monkeys (Cebus spp.). Tool use in capuchins is neither context specific nor stereotyped. The success of capuchins in using tools and in exploiting a variety of food resources in the wild derives from several factors: their manipulative abilities, interest in external objects and a tendency to explore the environment. In using tools, capuchins are similar to apes and more proficient than other monkey species. A cognitive approach indicates, however, that (in contrast with chimpanzees) they never develop an understanding of the requirements of the tool tasks presented.

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

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↗