Abstract # 41:

Scheduled for Saturday, September 13, 2014 05:00 PM-05:15 PM: Session 10 (Henry Oliver) Oral Presentation


A. E. Parrish1,2 and M. J. Beran1,2
1Georgia State University, Atlanta, GA, USA, 2Language Research Center, Atlanta, GA, USA
     Chimpanzees are highly proficient at making quantity discriminations, including when they choose between food sets. However, errors in quantity judgment sometimes emerge because of non-quantitative properties of alternative sets. For example, the presentation style in which foods are presented can alter their perceived amount. In Study 1, chimpanzees (N=3) chose between food quantities that were presented on different sized plates. Chimpanzees were highly accurate in control trials, selecting the larger of two food portions when both were presented on equal-sized plates (P < .001). However, they erroneously judged same-sized and smaller food portions to be larger in amount when they were presented on a small plate compared to an equal or larger food portion presented on a large plate (P < .01). In Study 2, chimpanzees (N=4) chose between two amounts of food presented in different sized cups. When different quantities were presented in the same-sized cups or when the small cup contained the larger quantity, chimpanzees were highly accurate in choosing the larger food amount (P < .01). However, when different-sized cups contained the same amount of food or the smaller cup contained the smaller amount of food (but looked relatively fuller) chimpanzees showed a bias to select the smaller but fuller cup (P < .05). Thus, chimpanzees misperceived food quantities in these contexts, and such errors match those reported in human consumption behavior.