RECOGNITION OF ASPECT-DEPENDENT 3-DIMENSIONAL OBJECTS BY AN ECHOLOCATING ATLANTIC BOTTLE-NOSED-DOLPHIN

We examined the ability of a bottlenose dolphin (Tursiops truncatus) t o recognize aspect-dependent objects using echolocation. An aspect-dep endent object such as a cube produces acoustically different echoes at different angles relative to the echolocation signal. The dolphin rec ognized the objects even though the objects were free to rotate and sw ay. A linear discriminant analysis and nearest centroid classifier cou ld classify the objects using average amplitude, center frequency, and bandwidth of object echoes. The results show that dolphins can use va rying acoustic properties to recognize constant objects and suggest th at aspect-independent representations may be formed by combining infor mation gleaned from multiple echoes.