- Unpublished master's thesis, University of Hawaii, Honolulu.
Judgments of Similarity of Rotated and Unrotated Objects by a
Bottlenosed Dolphin (Tursiops truncatus)
- Matthias Hoffmann-Kuhnt
University of Hawaii, Kewalo Basin Marine Mammal Lboratory, 1129
Ala Moana Blvd., Honolulu, HI, USA, 96814
-
- (C) 1994 University of Regensburg, Germany
In this study a male bottlenosed dolphin’s ability to judge
the similarity of rotated and unrotated figures in a visual two-alternative-matching-to-sample
task was examined. The dolphin was shown capable of recognizing
between two- and three-dimensional stimuli which differed only
in shape, but he was not able to distinguish between mirror image
stimuli. In the first experiment, the dolphin successfully learned
o use three display boxes, a stationing device, and response paddles
to indicate his choice in the matching task. Experiments 2 and
3 revealed a profound difficulty to recognize mirror image stimuli
in the matching task using several pairs of novel asymmetrical
objects. However, limited evidence for discriminating between
mirror images was revealed with two of seven pairs. Experiments
4 and 5 identified two key elements, rotation and feature displacement,
which are important components for being able to successfully
recognize mirror images, and tested the dolphin’s sensitivity
to these features. The dolphin was shown capable of discriminating
between different orientations of the same stimuli, if the disparity
was larger than 15&Mac176;, but he showed difficulties in differentiating
between objects consisting of the same features arranged differently.
The final experiment tested the dolphin’s ability to discriminate
asymmetrical rotated mirror images. Although he was not able to
significantly match these stimuli correctly to the sample, his
performance accuracy indicated that orientation of the stimuli
was not the sole basis for his responses. The results of all experiments
suggest that the dolphin had profound difficulties with the discrimination
of mirror image stimuli and that this may in part be due to the
nature of the matching task in which the dolphin was tested.
Hoffmann-Kuhnt, M. (1994). Judgments of Similarity of Rotated
and Unrotated Objects by a Bottlenosed Dolphin (Tursiops truncatus).
Unpublished master's thesis, Univeristy of Regensburg, Germany.
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