The Dolphin Institute - Dolphin Research Summaries

(C) 1988 University of Hawaii

Previous studied with bottlenosed dolphins underscored the difficulty these animals have in performing visual learning tasks, such as two-choice discriminations or matching-to sample, when task information appears in the form of simple 2-dimensional geometric or arbitrary shapes. In the present studies, a bottlenosed dolphin was trained in a visual delayed matching-to-sample task with 2-dimensional arbitrary stimuli. The subject was successful in transfer tests using novel 2-dimensional stimuli and in delayed matching with retention intervals as long as 60 seconds. High levels of performance were maintained as the stimulus size was successively reduced to sizes comparable to those used in previous studies. In the previous studies, each figure to be discriminated was displayed against its own small discrete background. In the present studies, the stimuli displayed against a large continuous background in a manner that presumably highlighted the 2-dimensional figures from their background. The results of the present studies suggest that the difficulties encountered in earlier work may have resulted from unfavorable or inadequate figure-ground relationships for the dolphins. In the dolphins’ natural environment, biologically relevant visual objects (e.g. prey or conspecifics) are set against a relatively large homogenous background. Dolphins may be prepared to locate and identify relevant visual objects where there initially exists a gross distinction between the object and its background. Once the figure-ground relationship has been identified, it seems possible to reduce the gross distinction without penalizing performance.

Hunter, G. A. (1988). Visual delayed matching of two-dimensional forms by a bottlenosed dolphin. Unpublished master's thesis, University of Hawaii, Honolulu.

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