Object recognition through eavesdropping: Passive echolocation in bottlenose dolphins

A bottlenose dolphin (Tursiops truncatus) demonstrated the ability to select the matching object in a matching-to-sample task after listening to another dolphin inspect the sample object via echolocation. The listener was prevented from inspecting the sample himself. In Experiment 1, with objects familiar to both dolphins, the listener’s performance was significantly better than chance. In Experiment 2, objects familiar to only one of the dolphins were used. On these trials, the listener’s performance was significantly better than chance only when the inspecting dolphin made a correct choice. Analysis of the listener’s responses when the inspector made an error demonstrated that this contingency was not due to the listener’s matching the inspector’s response, but was apparently due instead to inadequate information in the echo. The results suggest that the listener was able to “eavesdrop” on echoes produced by the inspector’s clicks and derive characteristics of the sample object.