Responses to familiar and unfamiliar objects by belugas (Delphinapterus leucas), bottlenose dolphins (Tursiops truncatus), and Pacific white-sided dolphins (Lagenorhynchus obliquidens)

Abstract

Previous research with bottlenose dolphins (Tursiops truncatus) demonstrated their ability to discriminate between familiar and unfamiliar stimuli. Dolphins gazed longer at unfamiliar stimuli. The current study attempted to extend this original research by examining the responses of three species of cetaceans to objects that differed in familiarity. Eleven belugas from two facilities, five bottlenose dolphins and five Pacific white-sided dolphins housed at one facility were presented different objects in a free-swim scenario. The results indicated that the animals gazed the longest at unfamiliar objects, but these gaze durations did not significantly differ from gaze durations when viewing familiar objects. Rather, the animals gazed longer at unfamiliar objects when compared to the apparatus alone. Species differences emerged with longer gaze durations exhibited by belugas and bottlenose dolphins and significantly shorter gaze durations for Pacific white-sided dolphins. It is likely that the animals categorized objects into familiar and unfamiliar categories, but the free-swim paradigm in naturalistic social groupings did not elicit clear responses. Rather this procedure emphasized the importance of attention and individual preferences when investigating familiar and unfamiliar objects, which has implications for cognitive research and enrichment use.

Do Belugas (Delphinapterus leucas), Bottlenose Dolphins (Tursiops truncatus), & Pacific White-Sided Dolphins (Lagenorhynchus obliquidens) Display Lateralized Eye Preference when Presented with Familiar or Novel Objects?

“…The current study replicated the experimental equipment and video recording set-up used by Yeater et al (2014) and Guarino et al (2017). The belugas and the lags were tested using underwater viewing windows located in their primary pools.…”

“…Familiar objects were presented multiple times throughout the project due to the limited availability and unfamiliar objects were presented only one time for each species. As documented in the supplementary material in Guarino et al (2017), some objects produced longer gaze durations and/or frequency of views, and numbers of individuals viewing the object (Supplementary Tables 2-4). No clear pattern emerged for unfamiliar or familiar objects or for specific objects, suggesting that salience of individual stimuli varied unpredictably.…”

“…The same experimental protocol was used for all populations and described in detail in Guarino et al (2017). Experimental sessions were conducted using a free swim context and daily social groupings.…”

“…The purpose of the current study was to evaluate the eye preference of three cetaceans when viewing objects outside of their aquatic habitat that had either been never experienced or seen by the animals (i.e., novel, unfamiliar objects) or that have been part of their typical enrichment program (i.e., familiar objects), extending the initial study in which gaze duration was assessed for belugas, bottlenose dolphins, and Pacific white-sided dolphins (Guarino, Yeater, Lacy, Dees, & Hill, 2017). The results of the initial object study conducted in a free swim, variable social setting indicated that while Pacific white-sided dolphins had significantly shorter gaze durations than either belugas or bottlenose dolphins, all three species looked longer at unfamiliar stimuli than at the control apparatus.…”

“…Two adult female belugas were excluded from the analyses due to visual impairments. See Guarino et al (2017) for specific details about the subjects.…”