title: Chimpanzee uses manipulative gaze cues to conceal and reveal information to foraging competitor.
abstract: Tactical deception has been widely reported in primates on a functional basis, but details of behavioral mechanisms are usually unspecified. We tested a pair of chimpanzees (Pan troglodytes) in the informed forager paradigm, in which the subordinate saw the location of hidden food and the dominant did not. We employed cross-correlations to examine temporal contingencies between chimpanzees' behavior: specifically how the direction of the subordinate's gaze and movement functioned to manipulate the dominant's searching behavior through two tactics, withholding, and misleading information. In Experiment 1, not only did the informed subordinate tend to stop walking toward a single high value food, but she also refrained from gazing toward it, thus, withholding potentially revealing cues from her searching competitor. In a second experiment, in which a moderate value food was hidden in addition to the high value food, whenever the subordinate alternated her gaze between the dominant and the moderate value food, she often paused walking for 5 s; this frequently recruited the dominant to the inferior food, functioning as a "decoy." The subordinate flexibly concealed and revealed gaze toward a goal, which suggests that not only can chimpanzees use visual cues to make predictions about behavior, but also that chimpanzees may understand that other individuals can exploit their gaze direction. These results substantiate descriptive reports of how chimpanzees use gaze to manipulate others, and to our knowledge are the first quantitative data to identify behavioral mechanisms of tactical deception.
  Cross correlations show a subordinate chimpanzee tactically deceived a dominant by not gazing toward a valuable food (withholding), and recruiting to a "decoy" food (misleading). Chimpanzees understand that others can exploit their gaze direction.
authors.affiliation: Chicago Zoological Society-Brookfield Zoo, Brookfield, Illinois.|School of Psychology, St Mary's College, University of St Andrews, St Andrews, Fife, UK.|Living Links, Yerkes National Primate Research Center, Emory University, Lawrenceville, Georgia.
authors.forename: Katie
authors.initials: K
authors.lastname: Hall
authors.affiliation: School of Psychology, St Mary's College, University of St Andrews, St Andrews, Fife, UK.
authors.forename: Mike W
authors.initials: MW
authors.lastname: Oram
authors.affiliation: Living Links, Yerkes National Primate Research Center, Emory University, Lawrenceville, Georgia.|California State University, Channel Islands, One University Drive, Camarillo, California.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Campbell
authors.affiliation: Living Links, Yerkes National Primate Research Center, Emory University, Lawrenceville, Georgia.|Department of Anthropology, University of Texas at Austin, Austin, Texas.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Eppley
authors.affiliation: School of Psychology, St Mary's College, University of St Andrews, St Andrews, Fife, UK.
authors.forename: Richard W
authors.initials: RW
authors.lastname: Byrne
authors.affiliation: Living Links, Yerkes National Primate Research Center, Emory University, Lawrenceville, Georgia.
authors.forename: Frans B M
authors.initials: FB
authors.lastname: de Waal
mesh_terms: D000818:Animals; D003463:Cues; D005247:Feeding Behavior; D005260:Female; D005502:Food; D002679:Pan troglodytes; D012919:Social Behavior
keywords: Machiavellian intelligence; Pan troglodytes; gaze following; informed forager paradigm; tactical deception