This study investigated whether Asian elephants can make relative quantity judgment (RQJ), a dichotomous judgment of unequal
quantities ordered in magnitude. In Experiment 1, elephants were simultaneously shown two baskets with differing quantities
of bait (up to 6 items). In Experiment 2, elephants were sequentially presented with baits, which could not be seen by elephants
in their total quantities. The task of elephants was to choose the larger quantity in both experiments. Results showed that
the elephants chose the larger quantity with significantly greater frequency. Interestingly, the elephants did not exhibit
disparity or magnitude effects, in which performance declines with a smaller difference between quantities in a two-choice
task, or the total quantity increases, respectively. These findings appear to be inconsistent with the previous reports of
RQJ in other animals, suggesting that elephants may be using a different mechanism to compare and represent quantities than
previously suggested for other species.
Keywords Numerical cognition - Relative quantity judgment - Elephants