Abstract # 55:

Scheduled for Saturday, September 17, 2011 03:45 PM-04:00 PM: Session 11 (Meeting Room 408)


K. Hall1,2, R. W. Byrne1, M. W. Oram1, M. W. Campbell2, T. M. Eppley2 and F. B. de Waal2
1University of St Andrews, School of Psychology, St Mary's College, South Street, St Andrews, Fife KY169JP, United Kingdom, 2Living Links Center, Yerkes NPRC, Emory University

Two pairs of chimpanzees (Pan troglodytes) competed in the informed forager paradigm to test whether an ignorant dominant could use behavioral cues from the knowledgeable subordinate in order to find hidden food, and whether the subordinate could avoid exploitation by withholding those cues. We predicted that the subordinate would engage in tactical deception by withholding information and misleading the dominant. We suggested gaze following as a mechanism to gain information and predicted that the dominant, in addition to physically following, would also rely on subtle tactics such as following the gaze of the subordinate. Data were collected over 14 months at Living Links, Yerkes NPRC. Videos were coded on a one-second time scale using Noldus Observer XT9 software to capture detailed gaze interactions. We analyzed data using cross correlations and compared them with an independent estimation of the potential noise distribution. We found that dominants followed the gaze of the subordinates towards the bait: three seconds before the subordinate gazed, the correlation coefficient of the dominant gazing was .1012 (864, ns); at the moment the subordinate gazed, the correlation coefficient was .1923 (863, p<.01); three seconds later, a relationship developed when the dominant gazed in the same direction, and the correlation coefficient was .2874 (798, p<.001). This statistical method allowed us to parse subtle gaze interactions and show how social information is acquired in chimpanzees.