Laterality of Eye Use by Bottlenose (Tursiops truncatus) and Rough-Toothed (Steno bredanensis) Dolphins While Viewing Predictable and Unpredictable Stimuli

Malin K Lilley,Amber J De Vere,Deirdre B Yeater

doi:10.46867/ijcp.2020.33.03.01

Abstract

Laterality of eye use has been increasingly studied in cetaceans. Research supports that many cetacean species keep prey on the right side while feeding and preferentially view unfamiliar objects with the right eye. In contrast, the left eye has been used more by calves while in close proximity to their mothers. Despite some discrepancies across and within species, laterality of eye use generally indicates functional specialization of brain hemispheres in cetaceans. The present study aimed to examine laterality of eye use in bottlenose dolphins (Tursiops truncatus) and rough-toothed dolphins (Steno bredanensis) under managed care. Subjects were video-recorded through an underwater window while viewing two different stimuli, one predictable and static and the other unpredictable and moving. Bottlenose dolphins displayed an overall right-eye preference, especially while viewing the unpredictable, moving stimulus. Rough-toothed dolphins did not display eye preference while viewing stimuli. No significant correlations between degree of laterality and behavioral interest in the stimuli were found. Only for bottlenose dolphins were the degree of laterality and curiosity ratings correlated. This study extends research on cetacean lateralization to a species not extensively examined and to stimuli that varied in movement and degree of predictability. Further research is needed to make conclusions regarding lateralization in cetaceans.

Highlights

Title Laterality of Eye Use by Bottlenose (Tursiops truncatus) and Rough-toothed (Steno bredanensis) Dolphins While Viewing Predictable and Unpredictable Stimuli
The present study aimed to examine laterality of eye use in bottlenose dolphins (Tursiops truncatus) and rough-toothed dolphins (Steno bredanensis) under managed care
Post-hoc follow-up analyses revealed that bottlenose dolphins were more likely to use their right eye (M = 45.82, SD = 17.33) compared to the left eye (M = 27.83, SD = 14.44; p < 0.01) and both eyes (M = 27.41, SD = 13.83; p < 0.01) regardless of the stimuli presented

Summary

Introduction

Title Laterality of Eye Use by Bottlenose (Tursiops truncatus) and Rough-toothed (Steno bredanensis) Dolphins While Viewing Predictable and Unpredictable Stimuli. Laterality of Eye Use by Bottlenose (Tursiops truncatus) and Rough-Toothed (Steno bredanensis) Dolphins While Viewing Predictable and Unpredictable. The present study aimed to examine laterality of eye use in bottlenose dolphins (Tursiops truncatus) and rough-toothed dolphins (Steno bredanensis) under managed care. Sakai et al (2006) found that bottlenose dolphins preferred to use the left flipper for flipper rubbing with social partners. The absence of flipper preference during object carrying discarded the hypothesis that left-flipper preference was related to laterality of motor abilities Taken together, these results support a specific function of the right cerebral hemisphere to process information during flipper rubbing (a social behavior) but not object carrying (an independent behavior). Lateralized behavior involving flipper preference was found in orcas; the right pectoral flipper was used more frequently than the left during flipper slapping at the surface (Giljov et al, 2016)

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