Chimpanzee food preferences, associative learning, and the origins of cooking

Some experiments in Warneken and Rosati (2015) presented methodological concerns. First, the experimenters presumably had an expectation that the chimpanzees might prefer one container over the other, and yet limited controls were in place to prevent the experimenter from cuing the chimpanzees (Beran, 2012). Second, their intertemporal choice test made use of pointing to food items as the measured response. It is difficult for nonhuman primates to inhibit pointing to larger or better amounts of visible food (e.g., Boysen & Berntson, 1995), and this leads to an interpretive dilemma regarding claims that pointing to more or better food is reflective of self-control by animals, rather than reflecting difficulty with inhibiting this prepotent response (for more on this point, see Beran et al., 2014; Paglieri et al., 2013).