Recognition and Discrimination of Human Actions Across the Senses of Echolocation and Vision in the Bottlenose Dolphin: Evidence for Dolphin Cross-modal Integration of Dynamic Information
Abstract
The ability of cetaceans to explore and interpret their world via echolocation has receivedconsiderable attention during recent years, and the resulting body of work has revealed asophisticated cetacean echolocation system. In addition, a number of recent studies suggest thatdolphins can relate information that they receive from vision with information that they obtainfrom echolocation when this information concerns stationary objects. However, the present studyis the first test of the cetacean ability to integrate dynamic information about movement acrossthe two senses. Three adult female bottlenose dolphins that had previously learned to interpretvisible movements produced by humans stationed on floating docks were asked to interpret a setof these movements produced by an underwater human located behind a visually opaque screen.Although each dolphin had previously demonstrated its ability to reliably interpret movementsproduced by a human in the air above the surface of the water, none of the dolphins had anyprevious experience with underwater humans producing movements that the dolphins could seeor with underwater humans producing movements behind an opaque screen that prevented thedolphins from using visual information to interpret these signals. The dolphins quickly learned tocorrectly respond to signals that they could not see but could observe via echolocation. Theseresults demonstrate that dolphins can relate visual and echoic representations of actions,although the amount of experience necessary for such integration has yet to be determined.