Dissecting the mechanisms of squirrel monkey (Saimiri boliviensis) social learning

Emulative learning of a two-step task in free-ranging domestic pigs

Previous research showed that young domestic pigs learn through observation of conspecifics by using social learning mechanisms like social facilitation, enhancement effects, and even object movement re-enactment. The latter suggests some form of emulative learning in which the observer learns about the object's movements and affordances. As it remains unclear whether pigs need a social agent to learn about objects, we provided 36 free-ranging domestic pigs with varying degrees of social to non-social demonstrations on how to solve a two-step manipulative foraging task: observers watched either a conspecific or a human demonstrator, or self-moving objects ("ghost control"), or a ghost control accompanied by an inactive conspecific bystander. In addition, 22 subjects that were previously tested without any demonstrator were used as a non-observer control. To solve the task, the subjects had to first remove a plug from its recess to then be able to slide a cover to the side, which would lay open a food compartment. Observers interacted longer with the relevant objects (plugs) and were more successful in solving the task compared to non-observers. We found no differences with regard to success between the four observer groups, indicating that the pigs mainly learned about the apparatus rather than about the actions. As the only common feature of the different demonstrations was the movement of the plug and the cover, we conclude the observer pigs learned primarily by emulation, suggesting that social agents are not necessary for pigs when learning through observation.

Leveraging Social Learning to Enhance Captive Animal Care and Welfare

From ants to zebras, animals are influenced by the behavior of others. At the simplest level, social support can reduce neophobia, increasing animals’ exploration of novel spaces, foods, and other environmental stimuli. Animals can also learn new skills more quickly and more readily after observing others perform them. How then can we apply animals’ proclivity to socially learn to enhance their care and welfare in captive settings? Here, I review the ways in which animals (selectively) use social information, and propose tactics for leveraging that to refine the behavioral management of captive animals: to enhance socialization techniques, enrichment strategies, and training outcomes. It is also important to consider, however, that social learning does not always promote the uniform expression of new behaviors. There are differences in animals’ likelihood to seek out or use socially provided information, driven by characteristics such as species, rank, age, and personality. Additionally, social learning can result in inexact transmission or the transmission of undesirable behaviors. Thus, understanding when, how, and why animals use social information is key to developing effective strategies to improve how we care for animals across settings and, ultimately, enhance captive animal welfare.

Organized to learn: the influence of social structure on social learning opportunities in a group

Social learning, which is a mechanism that allows an individual to acquire skills from other individuals, occurs in a social context. Therefore, factors that influence social context, like social structure, will impact social learning opportunities. This review explores how features of social structure affect social learning opportunities in primates, either through their relationship with social tolerance or through the number of social learning models. Features that are investigated in this review and that we hypothesize affect social learning opportunities are parental investment, dominance hierarchy, nepotism, social bonds, dispersal, group size, fission-fusion dynamics, and sex ratio. For most of these features we find evidence, but support varies. Of all primate species, only humans show all the requirements of an optimal social structure to promote social learning. Future research into social learning and culture should not overlook the social context in which it takes place.

Impaired social facilitation on voluntary exercise of BALB/cCrSlc mice, a proposed as an autism spectrum disorder model

Impaired social facilitation was reported in autism spectrum disorder (ASD) children. However, behavioral analysis methods of social facilitation for ASD model have not been reported. We developed a novel breeding home cage for social facilitation. Voluntary exercise of more social C57BL/6 J mice was significantly increased in the presence of observer mouse compared to that in the absence of observer mouse. In contrast, the presence of observer mouse did not affect voluntary exercise of less social BALB/cCrSlc mice. These suggest that BALB/cCrSlc mice, a mouse model of ASD, exhibited impaired social facilitation. Our method would provide novel clues for ASD pathophysiology.

Responses to Economic Games of Cooperation and Conflict in Squirrel Monkeys (Saimiri boliviensis)

Games from experimental economics have provided insights into the evolutionary roots of social decision making in primates and other species. Multiple primate species' abilities to cooperate, coordinate and anti-coordinate have been tested utilizing variants of these simple games. Past research, however, has focused on species known to cooperate and coordinate in the wild. To begin to address the degree to which cooperation and coordination may be a general ability that manifests in specific contexts, the present study assessed the decisions of squirrel monkeys (Saimiri boliviensis; N = 10), a species not known for their cooperative behavior in these games. Pairs of monkeys were presented with the Assurance Game (a coordination game), the Hawk-Dove Game (an anti-coordination game) and the Prisoner's Dilemma (a cooperation game with a temptation to defect). We then compared squirrel monkeys' performance to existing data on capuchin monkeys (Sapajus [Cebus] apella), a closely related species that routinely cooperates, to determine what, if any, differences in decision making emerged. Some pairs of both species found the payoff-dominant Nash Equilibrium (NE) in the coordination game, but failed to find the NE in subsequent games. Our results suggest that, like capuchins, squirrel monkeys coordinate their behavior with others, suggesting that such mutual outcomes occur in at least some contexts, even in species that do not routinely cooperate.

Learning of efficient behaviour in spatial exploration through observation of behaviour of conspecific in laboratory rats

Recent studies have suggested that rodent behaviour is influenced by the behaviour of surrounding conspecifics (e.g. emotional contagion and prosocial behaviour). However, little is known about deferred imitation and complex observational learning in rats. The purpose of this study was to reveal whether rats can learn from another rat's experiences. In a maze, observer rats watched the foraging behaviour of other rats (demonstrators) and then foraged in turn. The results showed that demonstrators explored inefficiently, but observers explored more efficiently after observing inefficient exploration by the demonstrators. This observational learning probably involved the acquisition of an efficient strategy through spatial exploration.

Studying primate cognition in a social setting to improve validity and welfare: a literature review highlighting successful approaches

BACKGROUND

Studying animal cognition in a social setting is associated with practical and statistical challenges. However, conducting cognitive research without disturbing species-typical social groups can increase ecological validity, minimize distress, and improve animal welfare. Here, we review the existing literature on cognitive research run with primates in a social setting in order to determine how widespread such testing is and highlight approaches that may guide future research planning.

SURVEY METHODOLOGY

Using Google Scholar to search the terms "primate" "cognition" "experiment" and "social group," we conducted a systematic literature search covering 16 years (2000-2015 inclusive). We then conducted two supplemental searches within each journal that contained a publication meeting our criteria in the original search, using the terms "primate" and "playback" in one search and the terms "primate" "cognition" and "social group" in the second. The results were used to assess how frequently nonhuman primate cognition has been studied in a social setting (>3 individuals), to gain perspective on the species and topics that have been studied, and to extract successful approaches for social testing.

RESULTS

Our search revealed 248 unique publications in 43 journals encompassing 71 species. The absolute number of publications has increased over years, suggesting viable strategies for studying cognition in social settings. While a wide range of species were studied they were not equally represented, with 19% of the publications reporting data for chimpanzees. Field sites were the most common environment for experiments run in social groups of primates, accounting for more than half of the results. Approaches to mitigating the practical and statistical challenges were identified.

DISCUSSION

This analysis has revealed that the study of primate cognition in a social setting is increasing and taking place across a range of environments. This literature review calls attention to examples that may provide valuable models for researchers wishing to overcome potential practical and statistical challenges to studying cognition in a social setting, ultimately increasing validity and improving the welfare of the primates we study.

Harnessing learning biases is essential for applying social learning in conservation

Social learning can influence how animals respond to anthropogenic changes in the environment, determining whether animals survive novel threats and exploit novel resources or produce maladaptive behaviour and contribute to human-wildlife conflict. Predicting where social learning will occur and manipulating its use are, therefore, important in conservation, but doing so is not straightforward. Learning is an inherently biased process that has been shaped by natural selection to prioritize important information and facilitate its efficient uptake. In this regard, social learning is no different from other learning processes because it too is shaped by perceptual filters, attentional biases and learning constraints that can differ between habitats, species, individuals and contexts. The biases that constrain social learning are not understood well enough to accurately predict whether or not social learning will occur in many situations, which limits the effective use of social learning in conservation practice. Nevertheless, we argue that by tapping into the biases that guide the social transmission of information, the conservation applications of social learning could be improved. We explore the conservation areas where social learning is highly relevant and link them to biases in the cues and contexts that shape social information use. The resulting synthesis highlights many promising areas for collaboration between the fields and stresses the importance of systematic reviews of the evidence surrounding social learning practices.

Captive chimpanzee foraging in a social setting: a test of problem solving, flexibility, and spatial discounting

In the wild, primates are selective over the routes that they take when foraging and seek out preferred or ephemeral food. Given this, we tested how a group of captive chimpanzees weighed the relative benefits and costs of foraging for food in their environment when a less-preferred food could be obtained with less effort than a more-preferred food. In this study, a social group of six zoo-housed chimpanzees (Pan troglodytes) could collect PVC tokens and exchange them with researchers for food rewards at one of two locations. Food preference tests had revealed that, for these chimpanzees, grapes were a highly-preferred food while carrot pieces were a less-preferred food. The chimpanzees were tested in three phases, each comprised of 30 thirty-minute sessions. In phases 1 and 3, if the chimpanzees exchanged a token at the location they collected them they received a carrot piece (no travel) or they could travel ≥10 m to exchange tokens for grapes at a second location. In phase 2, the chimpanzees had to travel for both rewards (≥10 m for carrot pieces, ≥15 m for grapes). The chimpanzees learned how to exchange tokens for food rewards, but there was individual variation in the time it took for them to make their first exchange and to discover the different exchange locations. Once all the chimpanzees were proficient at exchanging tokens, they exchanged more tokens for grapes (phase 3). However, when travel was required for both rewards (phase 2), the chimpanzees were less likely to work for either reward. Aside from the alpha male, all chimpanzees exchanged tokens for both reward types, demonstrating their ability to explore the available options. Contrary to our predictions, low-ranked individuals made more exchanges than high-ranked individuals, most likely because, in this protocol, chimpanzees could not monopolize the tokens or access to exchange locations. Although the chimpanzees showed a preference for exchanging tokens for their more-preferred food, they appeared to develop strategies to reduce the cost associated with obtaining the grapes, including scrounging rewards and tokens from group mates and carrying more than one token when travelling to the farther exchange location. By testing the chimpanzees in their social group we were able to tease apart the social and individual influences on their decision making and the interplay with the physical demands of the task, which revealed that the chimpanzees were willing to travel farther for better.

Chimpanzees copy dominant and knowledgeable individuals: implications for cultural diversity

Evolutionary theory predicts that natural selection will fashion cognitive biases to guide when, and from whom, individuals acquire social information, but the precise nature of these biases, especially in ecologically valid group contexts, remains unknown. We exposed four captive groups of chimpanzees (Pan troglodytes) to a novel extractive foraging device and, by fitting statistical models, isolated four simultaneously operating transmission biases. These include biases to copy (i) higher-ranking and (ii) expert individuals, and to copy others when (iii) uncertain or (iv) of low rank. High-ranking individuals were relatively un-strategic in their use of acquired knowledge, which, combined with the bias for others to observe them, may explain reports that high innovation rates (in juveniles and subordinates) do not generate a correspondingly high frequency of traditions in chimpanzees. Given the typically low rank of immigrants in chimpanzees, a 'copying dominants' bias may contribute to the observed maintenance of distinct cultural repertoires in neighboring communities despite sharing similar ecology and knowledgeable migrants. Thus, a copying dominants strategy may, as often proposed for conformist transmission, and perhaps in concert with it, restrict the accumulation of traditions within chimpanzee communities whilst maintaining cultural diversity.

The importance of witnessed agency in chimpanzee social learning of tool use

Social learning refers to individuals learning from others, including information gained through indirect social influences, such as the results of others' actions and changes in the physical environment. One method to determine the relative influence of these varieties of information is the 'ghost display', in which no model is involved, but subjects can watch the results that a model would produce. Previous research has shown mixed success by chimpanzees (Pan troglodytes) learning from ghost displays, with some studies suggesting learning only in relatively simple tasks. To explore whether the failure of chimpanzees to learn from a ghost display may be due to neophobia when tested singly or a requirement for more detailed information for complex tasks, we presented ghost displays of a tool-use task to chimpanzees in their home social groups. Previous tests have revealed that chimpanzees are unable to easily solve this tool-use task asocially, or learn from ghost displays when tested singly, but can learn after observing conspecifics in a group setting. In the present study, despite being tested in a group situation, chimpanzees still showed no success in solving the task via trial-and-error learning, in a baseline condition, nor in learning the task from the ghost display. Simply being in the presence of their group mates and being shown the affordances of the task was not sufficient to encourage learning. Following this, in an escalating series of tests, we examined the chimpanzees' ability to learn from a demonstration by models with agency: (1) a human; (2) video footage of a chimpanzee; (3) a live chimpanzee model. In the first two of these 'social' conditions, subjects showed limited success. By the end of the final open diffusion phase, which was run to determine whether this new behavior would be transmitted among the group after seeing a successful chimpanzee use the task, 83% of chimpanzees were now successful. This confirmed a marked overall effect of observing animate conspecific modeling, in contrast to the ghost condition. This article is part of a Special Issue entitled: insert SI title.

Goats favour personal over social information in an experimental foraging task

Animals can use their environments more efficiently by selecting particular sources of information (personal or social), according to specific situations. Group-living animals may benefit from gaining information based on the behaviour of other individuals. Indeed, social information is assumed to be faster and less costly to use than personal information, thus increasing foraging efficiency. However, when food sources change seasonally or are randomly distributed, individual information may become more reliable than social information. The aim of this study was to test the use of conflicting personal versus social information in goats (Capra hircus), in a foraging task. We found that goats relied more on personal than social information, when both types of information were available and in conflict. No effect of social rank was found on the occasions when goats followed other demonstrator goats. Goats are selective browsers/grazers and therefore relying on personal rather than social information could be the most efficient way to find patchily distributed resources in highly variable environments. Studies testing specific assumptions regarding the use of different sources of information can extend our understanding of decision making, including observed patterns of social learning.

When given the opportunity, chimpanzees maximize personal gain rather than "level the playing field"

We provided chimpanzees (Pan troglodytes) with the ability to improve the quality of food rewards they received in a dyadic test of inequity. We were interested to see if this provision influenced their responses and, if so, whether it was mediated by a social partner’s outcomes. We tested eight dyads using an exchange paradigm in which, depending on the condition, the chimpanzees were rewarded with either high-value (a grape) or low-value (a piece of celery) food rewards for each completed exchange. We included four conditions. In the first, “Different” condition, the subject received different, less-preferred, rewards than their partner for each exchange made (a test of inequity). In the “Unavailable” condition, high-value rewards were shown, but not given, to both chimpanzees prior to each exchange and the chimpanzees were rewarded equally with low-value rewards (a test of individual contrast). The final two conditions created equity. In these High-value and Low-value “Same” conditions both chimpanzees received the same food rewards for each exchange. Within each condition, the chimpanzees first completed ten trials in the Baseline Phase, in which the experimenter determined the rewards they received, and then ten trials in the Test Phase. In the Test Phase, the chimpanzees could exchange tokens through the aperture of a small wooden picture frame hung on their cage mesh in order to receive the high-value reward. Thus, in the Test Phase, the chimpanzees were provided with an opportunity to improve the quality of the rewards they received, either absolutely or relative to what their partner received. The chimpanzees responded in a targeted manner; in the Test Phase they attempted to maximize their returns in all conditions in which they had received low-value rewards during the Baseline Phase. Thus, the chimpanzees were apparently motivated to increase their reward regardless of their partners’, but they only used the mechanism provided when it afforded the opportunity for them to increase their rewards. We also found evidence that the chimpanzees’ responses were enhanced by social facilitation. Specifically, the chimpanzees were more likely to exchange their tokens through the frame when their test partner also did so, even in circumstances in which their reward value could not be improved. Our paradigm provided the chimpanzees with the possibility to improve the quality of rewards they received in the Test Phase. We found that refusals – to exchange tokens or to eat rewards – decreased significantly in the Test Phase compared to the Baseline Phase, where no such opportunity for improvement of outcomes existed. Thus, the chimpanzees participated more when they could improve the rewards they received.

Diffusion dynamics of socially learned foraging techniques in squirrel monkeys

Social network analyses and experimental studies of social learning have each become important domains of animal behavior research in recent years yet have remained largely separate. Here we bring them together, providing the first demonstration of how social networks may shape the diffusion of socially learned foraging techniques. One technique for opening an artificial fruit was seeded in the dominant male of a group of squirrel monkeys and an alternative technique in the dominant male of a second group. We show that the two techniques spread preferentially in the groups in which they were initially seeded and that this process was influenced by monkeys' association patterns. Eigenvector centrality predicted both the speed with which an individual would first succeed in opening the artificial fruit and the probability that they would acquire the cultural variant seeded in their group. These findings demonstrate a positive role of social networks in determining how a new foraging technique diffuses through a population.