Cooperatively breeding cottontop tamarins (Saguinus oedipus) do not donate rewards to their long-term mates.

This study tested the hypothesis that cooperative breeding facilitates the emergence of prosocial behavior by presenting cottontop tamarins (Saguinus oedipus) with the option to provide food rewards to pair-bonded mates. In Experiment 1, tamarins could provide rewards to mates at no additional cost while obtaining rewards for themselves. Contrary to the hypothesis, tamarins did not demonstrate a preference to donate rewards, behaving similar to chimpanzees in previous studies. In Experiment 2, the authors eliminated rewards for the donor for a stricter test of prosocial behavior, while reducing separation distress and food preoccupation. Again, the authors found no evidence for a donation preference. Furthermore, tamarins were significantly less likely to deliver rewards to mates when the mate displayed interest in the reward. The results of this study contrast with those recently reported for cooperatively breeding common marmosets, and indicate that prosocial preferences in a food donation task do not emerge in all cooperative breeders. In previous studies, cottontop tamarins have cooperated and reciprocated to obtain food rewards; the current findings sharpen understanding of the boundaries of cottontop tamarins’ food-provisioning behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Capuchins (Cebus apella) can solve a means-end problem.

Three capuchin monkeys (Cebus apella) were tested on a 2-choice discrimination task designed to examine their knowledge of support, modeled after Hauser, Kralik, and Botto-Mahan's (1999) experiments with tamarins. This task involved a choice between 2 pieces of cloth, including 1 with a food reward placed on its surface, and a second cloth with the food reward next to its surface. After reliably solving the basic problem, the capuchins were tested with various alternations of the original food reward and cloth. The capuchins were able to solve the initial task quickly, and generalize their knowledge to additional functional and nonfunctional variations of the problem. In comparison to the tamarins previously tested on this problem (Hauser et al., 1999), the capuchins were able to reach criterion faster during the training and food size conditions and showed a greater ability to inhibit reaching toward larger food rewards that were unavailable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relationship between problem solving and inhibitory control: Cotton-top tamarins ( Saguinus oedipus ) performance on a reversed contingency task.

To explore the relationship between problem solving and inhibitory control, the authors present 4 experiments on cotton-top tamarins (Saguinus oedipus) using a reverse-reward contingency task. In Experiment 1, 1 group of tamarins was given a choice between a small and a large quantity of food. Whichever quantity the tamarins reached for first, they received the alternative. The tamarins consistently picked the larger quantity, thereby receiving the smaller. A 2nd group of tamarins was given the same task, except that if they reached for the larger quantity of food, they received nothing. The tamarins continued to pick the larger quantity, even though this resulted in no food. In addition, most of the tamarins continued to pick the larger quantity even when the food payoff for choosing the smaller quantity was increased (Experiment 2) or when the visual salience of the food was reduced (Experiment 3). Experiment 4 was based on the finding that chimpanzees (Pan troglodytes) that have been trained on the concept of number can solve the reversed contingency task if the food is replaced by Arabic numerals. With the help of a color association, and a higher cost incurred by picking the color associated with 3 food items, the tamarins learned to pick the color associated with... (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibitory Control and Response Selection in Problem Solving: How Cotton-Top Tamarins (Saguinus oedipus) Overcome a Bias for Selecting the Larger Quantity of Food.

When presented with a choice between 1 and 3 pieces of food in a type of reversed contingency task, 4 cotton-top tamarins (Saguinus oedipus) consistently chose the 3 pieces of food and received nothing, even though the choice of 1 piece would have yielded 3. However, in a task in which the tamarins received the 1 piece of food when they chose it, all subjects learned to select 1 over 3. Thus, the tamarins' prior failure on the reversed contingency task did not result entirely from an inherent inability to suppress the prepotent response of reaching to the larger of 2 quantities of food. After the experience of selecting the smaller quantity and receiving it, all of the tamarins solved the version of the reversed contingency task that they failed initially. These results suggest that the tamarins' initial failure may have reflected a difficulty with selecting an alternative response option. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How Prosimian Primates Represent Tools: Experiments With Two Lemur Species (Eulemur fulvus and Lemur catta).

The authors examined how 2 lemur species (Eulemur fulvus and Lemur catta) reason about tools. Experiment 1 allowed subjects to use 1 of 2 canes to retrieve an inaccessible food reward. Lemurs learned to solve this problem as quickly as other primates. Experiment 2 then presented subjects with novel tools differing from the originals along one featural dimension. Subjects attended more to tools' sizes than to their colors and made no distinction between tools' shapes and textures. Experiments 3 and 4 presented problems in which some of the tools' orientations had to be modified relative to the food. Subjects performed well on these problems, sometimes modifying the position of the tool. These results are discussed in light of the performance of other primates on this task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What do rooks (Corvus frugilegus) understand about physical contact?

Rooks (Corvus frugilegus) do not use tools, but rapidly solve tests of physical cognition. The authors tested whether rooks understand the concept of physical contact using a task comprising a clear horizontal tube containing a stick with a disk attached to it and a piece of food. The rooks chose which side to pull the stick from to make the food accessible. Two configurations were used, with either the food or disk central along the tube. All 8 rooks solved the food-central configuration, but failed the disk-central configuration. Although they did not demonstrate an understanding of contact, further tests established that they could learn to solve these tasks provided there were salient stick cues. This result may arise because sticks are ecologically important for rooks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social communication about unpalatable foods in tamarins (Saguinus oedipus).

Many monkeys show social facilitation in sampling novel, palatable foods but not in avoiding unpalatable foods. Cotton-top tamarins (Saguinus oedipus) socially learned to avoid a preferred food when it was made unpalatable but showed no aversion toward a food not made unpalatable. Only 33% sampled unpalatable tuna, and few sampled it again. In 3 of 8 groups, the socially induced aversion was long lasting, at least 15 weeks after food was made palatable again. Potential cues include facial reactions of disgust, alarm-call vocalizations, and reduction in food-associated calls. Behavioral coordination in cooperative infant care, communication about food, and well-established social relationships may explain social avoidance of unpalatable foods in tamarins and the absence of social avoidance in less cooperative species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit chaining in cotton-top tamarins (Saguinus oedipus).

In implicit learning, human subjects are exposed to patterned information, but they are not informed about the pattern. Typically, they demonstrate learning of that pattern, but little awareness of the experimental contingencies. In a nonhuman analog of this procedure, two cotton-top tamarins (Saguinus oedipus) were presented with a five-element chain that consisted of the same icon presented serially at different locations on a touchscreen. The tamarins had to touch the icon at each location to advance the chain and receive reinforcement at the end of the chain. One element of the chain was never differentially reinforced in the presence of another element, as is typically done in transitive inference and serial chaining studies. Following training, the tamarins were tested for their knowledge of the chain using pairwise tests that are common in transitive inference and serial chaining experiments, and a random test, common in some types of implicit learning, in which the sequence of elements was randomized. The results of both tests revealed that the tamarins appreciated the ordinal position of the elements composing the chain, although reinforcement had not been dependent on that knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relation between food preference and food-elicited vocalizations in golden lion tamarins (Leontopithecus rosalia).

Reports the results of 2 studies on food-elicited vocalizations in golden lion tamarins. First, the preferences of 10 golden lion tamarins for 6 foods were investigated. Tamarins prefer mealworms and raisins significantly more than apple, egg, carrot, or marmoset diet. Food preference rank was significantly and positively correlated with the rank of latency to choose a particular food. Second, the relation between food preference and 15 vocal parameters measured from the calls emitted by 5 tamarins to a subset of the foods was investigated. Only 1 parameter was significantly correlated with food preference across animals. Within-Ss multivariate analysis of variance (ANOVA) showed that the vocalizations to foods are significantly different. Results support a hypothesis that food-elicited vocalizations vary in ways that correspond to the caller's preference but not in a manner that labels food type. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What guides a search for food that has disappeared? Experiments on cotton-top tamarins (Saguinus oedipus).

When food is launched down a vertically positioned S-shaped opaque tube, cotton-top tamarins (Saguinus oedipus) search for the food in the position directly beneath the release point, even though over several trials it never appears in this position (B. M. Hood et al., 1999). Experiment 1 showed that when the trajectory of the food shifts from the vertical to the horizontal plane, tamarins no longer show systematic perseverative errors and, in general, perform better on this invisible displacement task. Experiment 2 showed that tamarins with experience on the horizontal task show less of a bias when tested on the vertical task but nonetheless fail overall to solve this invisible displacement problem; their performance is substantially worse than it was on the horizontal task. Experiment 3 revealed that when the vertically positioned tube is replaced by an occluded ramp, tamarins consistently search in the compartment below the release point, even though most of the tamarins had experience in Experiments 1 and 2. Overall, results indicate that tamarins have a significant gravity bias when searching for food that has disappeared along the vertical plane but also have more general problems finding food that has moved out of sight. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Laterality in hand preferences and reaching accuracy of cotton-top tamarins (Saguinus oedipus).

Manual laterality of cotton-top tamarins (Saguinus oedipus) was observed for five different types of reaching. The tamarins displayed species-level right-handedness for spontaneous grasping for food but not for one-arm vertical suspension or any of 3 other types of elicited reaching. The results showed that difficult or novel tasks are neither necessary nor sufficient for the emergence of species-level handedness. Accuracy in retrieving food from a rotating platform was greatest (a) for highly lateralized tamarins, (b) when the preferred hands were used for reaching, (c) for young tamarins, and (d) when the tamarins stood on a narrow, unstable platform instead of a wide, stable one. The results suggest that evolution of species-level handedness is dependent on prior natural selection for increased manual performance that accompanies strongly lateralized hand preferences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social Transmission of Flavor Preferences in Two Species of Hamsters (Mesocricetus auratus and Phodopus campbelli).

Golden hamsters (Mesocricetus auratus) and dwarf hamsters (Phodopus campbelli) interacted with a conspecific demonstrator that had recently consumed a flavored food. When given a choice between their demonstrator's flavor and another flavor, the dwarf hamsters preferred the flavor their demonstrator had eaten. Golden hamsters did not prefer their demonstrators' diets when the demonstrators were unrelated adults or littermates, but they did when the demonstrator was their mother. Videotaping the interactions between demonstrators and observers revealed that adult golden hamsters did not investigate foods hoarded by their demonstrators whereas dwarf hamsters did. These results are interpreted in terms of the stimuli that activate feeding behavior systems in these 2 hamster species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Constraints on problem solving and inhibition: Object retrieval in cotton-top tamarins (Saguinus oedipus oedipus).

Problem solving relies on a combination of the capacity to generate appropriate solutions and the ability to inhibit prepotent inappropriate responses. Often, problems with the latter prevent some animals from performing well on problem-solving tasks. The authors used the object retrieval task to examine inhibition in cotton-top tamarins (Saguinus oedipus oedipus). They found that, like human infants, tamarins had difficulty retrieving a reward from inside a transparent box when the opening was on the side because they could not inhibit the tendency to reach straight into the solid face of the box. However, subjects trained with an opaque box prior to testing on the transparent box performed perfectly. These results suggest that although the inability to inhibit prepotent biases prevents individuals from acquiring an initial strategy, sufficient training on an effective strategy may allow animals to overcome their initial difficulties with tasks requiring inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chimpanzee (Pan troglodytes) relational matching: Playing by their own (analogical) rules.

Chimpanzees (Pan troglodytes) have been known to exhibit rudimentary abilities in analogical reasoning (Flemming, Beran, Thompson, Kleider, & Washburn, 2008; Gillian, Premack, & Woodruff, 1981; Haun & Call, 2009; Thompson & Oden, 2000; Thompson, Oden, & Boysen, 1997). With a wide array of individual differences, little can be concluded about the species' capacity for analogies, much less their strategies employed for solving such problems. In this study, we examined analogical strategies in 3 chimpanzees using a 3-dimensional search task (e.g., Kennedy & Fragaszy, 2008). Food items were hidden under 1 of 2 or 3 plastic cups of varying sizes. Subsequently, chimpanzees searched for food under the cup of the same relative size in their own set of cups—reasoning by analogy. Two chimpanzees initially appeared to fail the first relational phase of the task. Meta-analyses revealed, however, that they were instead using a secondary strategy not rewarded by the contingencies of the task—choosing on the basis of the same relative position in the sample. Although this was not the intended strategy of the task, it was nonetheless analogical. In subsequent phases of the task, chimpanzees eventually learned to shift their analogical reasoning strategy to match the reward contingencies of the task and successfully choose on the basis of relative size. This evidence not only provides support for the analogical ape hypothesis (Thompson & Oden, 2000), but also exemplifies how foundational conceptually mediated analogical behavior may be for the chimpanzee. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Comparative analysis of sociality in lion tamarins (Leontopithecus rosalia) and marmosets (Callithrix kuhli): Responses to separation from long-term pairmates.

The purpose of the present study was to examine responses to a short-term separation from the partner in 2 species of pair-bonding primates: lion tamarins (Leontopithecus rosalia) and marmosets (Callithrix kuhli). Observations were conducted on well-established pairs during a preseparation baseline, a 1-hr separation, and a postseparation reunion. Lion tamarins responded to separation with increased levels of distress, relative to marmosets. Affiliative behavior increased in marmosets upon reunion, whereas affiliative behavior decreased upon reunion in lion tamarins. In marmosets, there were more trials in which sexual interactions were recorded during the postseparation reunion, whereas in lion tamarins, no increases were observed. The results indicate that the mechanisms responsible for the maintenance of social and sexual relationships may differ in these 2 species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial cues more salient than color cues in cotton-top tamarins (Saguinus oedipus) reversal learning.

Animals living in stable home ranges have many potential cues to locate food. Spatial and color cues are important for wild Callitrichids (marmosets and tamarins). Field studies have assigned the highest priority to distal spatial cues for determining the location of food resources with color cues serving as a secondary cue to assess relative ripeness, once a food source is located. We tested two hypotheses with captive cotton-top tamarins: (a) Tamarins will demonstrate higher rates of initial learning when rewarded for attending to spatial cues versus color cues. (b) Tamarins will show higher rates of correct responses when transferred from color cues to spatial cues than from spatial cues to color cues. The results supported both hypotheses. Tamarins rewarded based on spatial location made significantly more correct choices and fewer errors than tamarins rewarded based on color cues during initial learning. Furthermore, tamarins trained on color cues showed significantly increased correct responses and decreased errors when cues were reversed to reward spatial cues. Subsequent reversal to color cues induced a regression in performance. For tamarins spatial cues appear more salient than color cues in a foraging task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the reduction of dodging in mice: A comparison of food wrenching and dodging in rats (Rattus norvegicus) and mice (Mus musculus).

Rats attempt to steal food from conspecifics by approaching them from the side to wrench the food from the victims' paws, but victims dodge laterally away to protect their food. Given the pervasive necessity of obtaining food, it might be expected that the behaviors of food wrenching and dodging would be common to many animals, but this idea has not been examined. In the present study, food wrenching and dodging were compared in Long-Evans and Sprague-Dawley rats (Rattus norvegicus) and out-crossed CDF1 and inbred C57b mice (Mus musculus). Mice stole food using a strategy very similar to that of rats, but they did not dodge in an open field test and dodged less in a home cage test and ran away or fought more than rats. There were no strain differences in rats, but C57b mice dodged less than CDF1 mice. Given that dodging is a component not only of food defensive behavior but also of play, sexual, and aggressive behavior, the species and strain difference may be a marker (or a key element) of changes in social behaviors that have occurred since the evolutionary separation of rats and mice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Patterns of social preference across different social contexts in golden lion tamarins (Leontopithecus rosalia).

We investigated the role of mutual and circumstantial factors in maintaining exclusive social relationships in a New World primate. Four breeding pairs of golden lion tamarins (Leontopithecus rosalia rosalia) were allowed to interact with their mate or an unfamiliar, opposite-sex adult in each of 4 different social contexts: in view of the mate, out of the mate's view, with only the mate present, and with only the unfamiliar animal present. Males and females were in proximity to, approached, and sniffed their mates significantly more often than they did unfamiliar tamarins. These behaviors suggest a preference for the familiar mate. However, when mates were absent, tamarins demonstrated significantly higher levels of approach and sniffs toward unfamiliar animals. These patterns of behavior indicate that circumstantial factors, such as social context, may regulate social interactions between paired tamarins and unfamiliar, opposite-sex conspecifics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of experimenter-given cues in visual co-orienting and in an object-choice task by a New World monkey species, Cotton Top Tamarins ( Saguinus oedipus ).

Two methods assessed the use of experimenter-given directional cues by a New World monkey species, cotton top tamarins (Saguinus oedipus). Experiment 1 used cues to elicit visual co-orienting toward distal objects. Experiment 2 used cues to generate responses in an object-choice task. Although there were strong positive correlations between monkey pairs to co-orient, visual co-orienting with a human experimenter occurred at a low frequency to distal objects. Human hand pointing cues generated more visual co-orienting than did eye gaze to distal objects. Significant accurate choices of baited cups occurred with human point and tap cues and human look cues. Results highlight the importance of head and body orientation to induce shared attention in cotton top tamarins, both in a task that involved food getting and a task that did not. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What do bonobos (Pan paniscus) understand about physical contact?

The present study aimed to test what bonobos (Pan paniscus) understand about contact. The task consisted of a clear horizontal tube containing a piece of food and a stick with a disk attached. The bonobos chose which side to push or pull the stick for the disk to contact the food and make it accessible. There were 9 variations in tube design, which differed in the positions of the stick, disk, and food. All 5 bonobos passed at least 1 configuration. A recent study (A. E. Helme, N. S. Clayton, & N. J. Emery, 2006) found that rooks could learn only tube configurations that provided an asymmetrical stick cue, whereas bonobos did not demonstrate an understanding of contact but showed more individual variation, attending to the positions of the food, disk, and stick. (PsycINFO Database Record (c) 2010 APA, all rights reserved)