Ring-tailed lemurs (Lemur catta) exploit information about what others can see but not what they can hear
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Studies suggest that haplorhine primates are sensitive to what others can see and hear. Using two experimental designs, we tested the hypothesis that ring-tailed lemurs (N = 16) are also sensitive to the visual and auditory perception of others. In the first task, we used a go/no–go design that required lemurs to exploit only auditory information. In the second task, we used a forced-choice design where lemurs competed against a human who would prevent them from obtaining food if their approaches were detected. Subjects were given the choice of obtaining food silently or noisily when the competitor’s back was turned. They were also given the choice to obtain food when the competitor could either see them or not. Here, we replicate the findings of previous studies indicating that ring-tailed lemurs are sensitive to whether they can be seen; however, we found no evidence that subjects are sensitive to whether others can hear them. Our findings suggest that ring-tailed lemurs converge with haplorhine primates only in their sensitivity to the visual information of others. The results emphasize the importance of investigating social cognition across sensory domains in order to elucidate the cognitive mechanisms that underlie apparently complex social behavior. These findings also suggest that the social dynamics of haplorhine groups impose greater cognitive demands than lemur groups, despite similarities in total group size.
KeywordsSocial cognition Social intelligence hypothesis Sensory domains Perspective taking
We extend our gratitude to the Duke Lemur Center staff, especially Dr. Erin Ehmke and David Brewer, for their support and assistance. For help with data collection and coding, we thank Jeremy Clift, Aidan Coleman, Leah Kaiser, Cayley Larimer, Kara Leimberger, Seth Madlon-Kay, Meiying Qin, and Judy Songrady. We thank Drs. Leslie Digby, Ian Gilby, and Anne Yoder, along with Aaron Sandel and Brandon Semel, for their comments on previous drafts of the manuscript. We also thank two anonymous reviewers for their constructive feedback on the original submission. JB was funded by the Duke Undergraduate Research Support Office and the Duke Lemur Center’s Molly Glander Award. CK was supported by NSF GRFP DGE-1106401. This work was also supported in part by National Science Foundation Grants NSF-BCS-08-27552-02 and NSF-BCS-10-25172 to BH. This is Duke Lemur Center publication #1255.
Ethical approval was given by the Duke University Institutional Animal Care and Use Committee (Protocol #: A199-11-08) and veterinarians at the Duke Lemur Center.
Conflict of interest
The authors declare that they have no conflict of interest.
Example trials of the familiarization and pretest for Experiment 1 (MP4 734 kb)
Example trials of the motivational and competitive conditions for Experiment 1 (MP4 571 kb)
Example trials of the face-back and face-forward conditions for Experiment 2 (MP4 1463 kb)
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