CDT Researchers installed mirrors at the New York Aquarium to determine whether two bottlenose dolphins could show that they are self-aware enough to gaze at their own reflected image of markings placed on their bodies. Both dolphins spent a great deal of time staring at temporary ink marks placed on their face and sides, according to Diana Reiss of Columbia University and Lori Marino of Emory University in their report Tuesday in the Proceedings of the National Academy of Sciences. Mirror self-recognition in chimpanzees was demonstrated in earlier studies when it was shown that animals responded to body marks.
Humans learn to relate a mirrored image to themselves at an early age.
The ability indicates a self-awareness some experts think is reserved for only higher primates. Monkeys, lesser apes and elephants have failed to demonstrate this ability, researchers say. But Reiss and Marino said that their experiment showed that chimpanzees and dolphins react in a similar ways when investigating body marks that could be viewed only by a mirror. Mirrors were placed in the dolphins' pools at the aquarium. The dolphins were then marked with a non-toxic ink and allowed to swim over to the mirrors.