Visual laterality in belugas (Delphinapterus leucas) and Pacific white-sided dolphins (Lagenorhynchus obliquidens) when viewing familiar and unfamiliar humans

Abstract

Lateralization of cognitive processes and motor functions has been demonstrated in a number of species, including humans, elephants, and cetaceans. For example, bottlenose dolphins (Tursiops truncatus) have exhibited preferential eye use during a variety of cognitive tasks. The present study investigated the possibility of visual lateralization in 12 belugas (Delphinapterus leucas) and six Pacific white-sided dolphins (Lagenorhynchus obliquidens) located at two separate marine mammal facilities. During free swim periods, the belugas and Pacific white-sided dolphins were presented a familiar human, an unfamiliar human, or no human during 10-15 min sessions. Session videos were coded for gaze duration, eye presentation at approach, and eye preference while viewing each stimulus. Although we did not find any clear group level lateralization, we found individual left eye lateralized preferences related to social stimuli for most belugas and some Pacific white-sided dolphins. Differences in gaze durations were also observed. The majority of individual belugas had longer gaze durations for unfamiliar rather than familiar stimuli. These results suggest that lateralization occurs during visual processing of human stimuli in belugas and Pacific white-sided dolphins and that these species can distinguish between familiar and unfamiliar humans.

Cheetahs discriminate familiar and unfamiliar human voices

“…repelling) are also able to discriminate between familiar and unfamiliar persons (e.g. dolphins ( Delphinidae ) 16 , 17 , crow ( Corvus brachyrhychos ) 18 , magpie ( Pica pica ) 19 ). Beyond a possible domestication effect, the simple relative proximity with humans may thus provide an opportunity for such learning with an obvious interest in terms of survival value 20 .…”

Diffusion tractography reveals pervasive asymmetry of cerebral white matter tracts in the bottlenose dolphin (Tursiops truncatus)

“…It would be of interest in future DTI investigations of T. truncatus and other cetaceans to compare the lateralization of this direct auditory pathway to that of the arcuate fasciculus. In addition to the proposed functional lateralization of social acoustic signals, arcuate asymmetry may also be relevant to accumulating reports of behavioral lateralization in delphinoids regarding visual (Karenina et al 2010 ; Thieltges et al 2011 ; Karenina et al 2013a , b ; Yeater et al 2014 ), somatosensory, and motor (Johnson and Moewe 1999 ; Sakai et al 2006 ; Hill et al 2015 ) social signaling.…”

Spontaneous approaches of divers by free-ranging orcas (Orcinus orca): age- and sex-differences in exploratory behaviours and visual laterality

“…In captivity, the left eye was preferentially used by bottlenose dolphins ( Tursiops truncatus ) to observe a human being, familiar or not, approaching the pool 17 . The individual left eye lateralized preferences were later confirmed by studies with captive belugas and pacific white-sided dolphins ( Lagenorhynchus obliquidens ) 43 . In the same experimental conditions, when the human being was replaced by an object, the degree of familiarity with the observed item was important.…”

“…All in all, the mother, the human (assimilated to the one that is providing care and food) and the toys in captivity are preferentially processed by the right hemisphere, whereas prey and new objects are processed by the left hemisphere. Interestingly, the degree of familiarity with the human or object observed also influenced gaze duration in several cetacean species 21 , 43 – 45 . The question thus remains open as to whether or not the observer’s attention and motivational state may be a determining factor.…”

“…Previous studies in cetaceans (e.g. dolphins and belugas) have shown that gaze duration (and possibly swimming speed and distance of approach) plays a key role during exploration of familiar and unfamiliar humans and objects 21 , 43 – 45 . Although the exploratory behaviours of cetaceans have still been poorly described in the literature, particular behaviours like head and body movements, some being associated with vocalisations (notably echolocation), have also been previously described in this context 61 , 62 .…”