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.

Understanding intraspecific variation in sociality is essential for characterizing the flexibility and evolution of social systems, yet its study in nonhuman animals is rare. Here, we investigated whether chimpanzees exhibit population-level differences in sociality that cannot be easily explained by differences in genetics or ecology. We compared social proximity and grooming tendencies across four semiwild populations of chimpanzees living in the same ecological environment over three consecutive years, using both linear mixed models and social network analysis. Results indicated temporally stable, population-level differences in dyadic-level sociality. Moreover, group cohesion measures capturing network characteristics beyond dyadic interactions (clustering, modularity, and social differentiation) showed population-level differences consistent with the dyadic indices. Subsequently, we explored whether the observed intraspecific variation in sociality could be attributed to cultural processes by ruling out alternative sources of variation including the influences of ecology, genetics, and differences in population demographics. We conclude that substantial variation in social behavior exists across neighboring populations of chimpanzees and that this variation is in part shaped by cultural processes.

Studies of animal behavior consistently demonstrate that the social environment impacts cooperation, yet the effect of social dynamics has been largely excluded from studies of human cooperation. Here, we introduce a novel approach inspired by nonhuman primate research to address how social hierarchies impact human cooperation. Participants competed to earn hierarchy positions and then could cooperate with another individual in the hierarchy by investing in a common effort. Cooperation was achieved if the combined investments exceeded a threshold and the higher ranked individual distributed the spoils unless control was contested by the partner. Compared to a condition lacking hierarchy, cooperation declined in the presence of a hierarchy due to a decrease in investment by lower ranked individuals. Furthermore, hierarchy was detrimental to cooperation regardless of whether it was earned or arbitrary. These findings mirror results from nonhuman primates and demonstrate that hierarchies are detrimental to cooperation. However, these results deviate from nonhuman primate findings by demonstrating that human behavior is responsive to changing hierarchical structures and suggests partnership dynamics that may improve cooperation. This work introduces a controlled way to investigate the social influences on human behavior and demonstrates the evolutionary continuity of human behavior with other primate species.

Social tolerance is generally treated as a stable, species-specific characteristic. Recent research, however, has questioned this position and emphasized the importance of intraspecific variation. We investigate the temporal stability of social tolerance in four groups of sanctuary-housed chimpanzees over eight years using a commonly employed measure: experimental cofeeding tolerance. We then draw on longitudinal data on the demographic composition of each group to identify the factors associated with cofeeding tolerance. We find appreciable levels of variation in cofeeding tolerance across both groups and years that correspond closely to changes in group-level demographic composition. For example, cofeeding tolerance is lower when there are many females with young infants. These results suggest that social tolerance may be a “responding trait” of chimpanzee sociality, reflecting individual-level behavioral responses to social changes. Additional, experimental research is needed to better model the causal drivers of social tolerance within and among species.

Animal ambassador programs are increasingly prevalent in zoos, yet few studies have investigated their impact on animal welfare. We assessed the effects of an ambassador program on the behavior of a colony (N = 15) of zoo-housed African penguins (Spheniscus demersus) and evaluated whether individual characteristics were predictive of participation. Behavioral data were collected for 16 weeks and included 43 “penguin encounters”, during which zoo visitors entered a designated portion of the penguins’ enclosure. When comparing colony behavior following encounters to behavior during a matched control period lacking an encounter, we found no significant difference between affiliative or aggressive behaviors, suggesting that the encounters did not disrupt interactions in the colony. The same was true when comparing behavior preceding the encounter to a matched control period, indicating that any anticipatory period was similarly non-disruptive. Space use during encounters suggested comfort near visitors. We also measured penguin temperament on the shy-bold continuum by recording the birds’ response to novel objects and found that penguins’ temperament, sex, and age were predictive of participation. We concluded that this program had a neutral or positive impact on penguin welfare and considered the findings in relation to aspects of the ambassador program that provided penguins with control over their involvement.

Observational behavior research is an important activity for zoos and aquariums, often being conducted to provide insights into welfare and guide management decisions. This research relies on standardized protocols to ensure consistent data collection. Inter-observer reliability, where untrained observers are tested against the behavior identifications of an expert observer, represent a critical internal validation process. Recent software advances have made reliability testing easier and more accessible, but there is limited guidance on what constitutes a strong reliability test. In this study, we reviewed historic reliability test data from Lincoln Park Zoo’s on-going behavior monitoring program. Six representative species were chosen that included 645 live pairwise reliability tests conducted across 163 total project observers. We identified that observers were being tested on only approximately 25% of the behaviors listed and defined in the species ethograms. Observers did encounter a greater percent of the ethogram with successive reliability tests, but this gap remained large. While inactive behaviors were well-represented during reliability tests, social and other non-maintenance solitary behaviors (e.g., exploratory, scent marking, play, etc.) did not frequently occur during tests. While the ultimate implications of these gaps in testing are unclear, these results highlight the risks of live reliability testing as an inherently non-standardized process. We suggest several approaches to help address these limitations, including refining ethograms, reconsidering criteria, and supplementing live training with video. We hope this self-critique encourages others to critically examine their methods, enhance the quality of their behavioral data, and ultimately, strengthen conclusions drawn about animal behavior and welfare.