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

Cetacean responses to violation of expectation paradigm in a free-swim context

The investigation of individual responses to unexpected stimuli or outcomes provides insights into basic cognitive processes, such as mental representations, emotional states of surprise, and detections of anomalies. Three experiments using a violation of expectation paradigm were conducted with 12 belugas and 17 bottlenose dolphins in managed care to test two classes of stimuli (humans and objects) in manipulated sequences of familiar and unfamiliar humans (Study 1, trainers and strangers), familiar and unfamiliar objects (Study 2, typical enrichment devices and new objects), and finally objects and humans (Study 3). Gaze durations were assessed for each condition in a given study during free-swim contexts. The results supported previous findings that visual stimuli, regardless of class, were stimulating and intriguing for both belugas and bottlenose dolphins. Belugas were more likely to gaze longer at human and object stimuli and tended to gaze longer at unexpected experiences than control or expected experiences. Bottlenose dolphins showed similar trends except when objects were involved. Individual variability was present for both species with some individuals showing stronger patterns of responses for expected experiences than others. After 2 years of intermittent experiments, belugas and bottlenose dolphins in managed care maintained their curiosity about visual stimuli, for which they received no primary reinforcement. Investigating responses to unexpected stimuli with animals in managed care may provide insight into how these animals respond to biologically relevant conditions, such as boat presence, predators, and unfamiliar conspecifics.

Replications, Comparisons, Sampling and the Problem of Representativeness in Animal Cognition Research

Animal cognition research often involves small and idiosyncratic samples. This can constrain the generalizability and replicability of a study's results and prevent meaningful comparisons between samples. However, there is little consensus about what makes a strong replication or comparison in animal research. We apply a resampling definition of replication to answer these questions in Part 1 of this article, and, in Part 2, we focus on the problem of representativeness in animal research. Through a case study and a simulation study, we highlight how and when representativeness may be an issue in animal behavior and cognition research and show how the representativeness problems can be viewed through the lenses of, i) replicability, ii) generalizability and external validity, iii) pseudoreplication and, iv) theory testing. Next, we discuss when and how researchers can improve their ability to learn from small sample research through, i) increasing heterogeneity in experimental design, ii) increasing homogeneity in experimental design, and, iii) statistically modeling variation. Finally, we describe how the strongest solutions will vary depending on the goals and resources of individual research programs and discuss some barriers towards implementing them.

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

Running comparative studies of laterality in mammals is a way to deepen our understanding of the evolution of the brain hemisphere functions. Studies on vision highlighted a possible task-sharing between hemispheres depending on the characteristics of the observers, the nature of the observed stimulus and the context of the observation, a phenomenon that could go beyond the monitoring of conspecifics. Cetaceans are predators that adapted to an aquatic habitat and display a clear crossing of fibers to the side of the brain opposite the eye of origin. Here, we analysed the interactions between humans and cetaceans when free-ranging orcas approach divers. Our study concentrated on the spontaneous exploratory behaviours of divers by orcas depending on their age and sex, and on the possible expression of a visual laterality. The results showed a significant preference for the use of the left eye but exclusively in adult females. Adult males had a more sustained attention than adult females, marked by a higher spatial proximity to divers, slower approaches and longer look durations. Adult females, probably more cautious, explored from the distance and more furtively. Our findings support a possible link between attentional/motivational states and visual laterality in mammals.