Thinking with their trunks: elephants use smell but not sound to locate food and exclude nonrewarding alternatives

The two-way object choice paradigm has been used extensively in studies of animal cognition. The paradigm involves presenting two options, one rewarding and one nonrewarding, to a subject and allowing it to make a choice between the two, potentially by exploiting specific cues provided by the experimenter. Using the paradigm, we tested first whether Asian elephants, Elephas maximus, could use auditory and/or olfactory cues to find food. While elephants were unable to locate hidden food by following an auditory cue, they were capable of finding food when the cue was olfactory. The second part of the study involved providing the subjects with only olfactory information about one option before presenting them with a choice between two. In trials in which subjects were allowed to investigate only the nonrewarding option, they made choices by exclusion, either inferring the location of the rewarding option or simply avoiding the nonrewarding one. Elephants thus relied on olfaction to locate food and to exclude nonrewarding food locations, but failed to use auditory information (when it was the only cue presented) to do the same. This study represents important evidence of elephants using their sense of smell in a cognitive task.