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Free keywords:
object permanence; short-term memory; acoustic cues; giraffe; Bayesian statistics
Abstract:
Although behavior, biology, and ecology of giraffes have been widely studied, little is known about their
cognition. Giraffes’ feeding ecology and their fission–fusion social dynamics are comparable with those
of chimpanzees (
Pan troglodytes
), suggesting that they might have complex cognitive abilities. To assess
this, we tested 6 captive giraffes on their object permanence, short-term memory, and ability to use
acoustic cues to locate food. First, we tested whether giraffes understand that objects continue to exist
even when they are out of sight. Giraffes saw one of two opaque containers containing food, then
containers were closed, an
d 2 s later giraffes could choose one. Second, we measured giraffes’ memory
repeating the procedure but with a delay of 30 s, 60 s, or 2 min between closing the containers and
subjects’ choice. Finally, we investigated whether giraffes could locate food inside one of two identical
opaque containers, when the only cue provided was the sound made by food when shaking the baited
container, or the lack of sound when shaking the empty container. Our results show that giraffes form
mental representations of completely hidden objects, but may not store them for longer than 30 s.
Moreover, they rely on stimulus enhancement rather than acoustic cues to locate food, when no visual
cues are provided. Finally, we argue that giraffes and other ungulates might be a suitable model to
investigate the evolution of complex cognitive abilities from a comparative perspective.
