title: Acoustic basis for recognition of aspect-dependent three-dimensional targets by an echolocating bottlenose dolphin.
abstract: The relationships between acoustic features of target echoes and the cognitive representations of the target formed by an echolocating dolphin will influence the ease with which the dolphin can recognize a target. A blindfolded Atlantic bottlenose dolphin (Tursiops truncatus) learned to match aspect-dependent three-dimensional targets (such as a cube) at haphazard orientations, although with some difficulty. This task may have been difficult because aspect-dependent targets produce different echoes at different orientations, which required the dolphin to have some capability for object constancy across changes in echo characteristics. Significant target-related differences in echo amplitude, rms bandwidth, and distributions of interhighlight intervals were observed among echoes collected when the dolphin was performing the task. Targets could be classified using a combination of energy flux density and rms bandwidth by a linear discriminant analysis and a nearest centroid classifier. Neither statistical model could classify targets without amplitude information, but the highest accuracy required spectral information as well. This suggests that the dolphin recognized the targets using a multidimensional representation containing amplitude and spectral information and that dolphins can form stable representations of targets regardless of orientation based on varying sensory properties.
authors.affiliation: Department of Psychology, University of Auckland, New Zealand.
authors.forename: D A
authors.initials: DA
authors.lastname: Helweg
authors.forename: W W
authors.initials: WW
authors.lastname: Au
authors.forename: H L
authors.initials: HL
authors.lastname: Roitblat
authors.forename: P E
authors.initials: PE
authors.lastname: Nachtigall
mesh_terms: D000162:Acoustics; D000818:Animals; D004289:Dolphins / Q000502:physiology*; D004455:Echolocation / Q000502:physiology*; D008297:Male