Reading faces: differential lateral gaze bias in processing canine and human facial expressions in dogs and 4-year-old children

Sensitivity to the emotions of others provides clear biological advantages. However, in the case of heterospecific relationships, such as that existing between dogs and humans, there are additional challenges since some elements of the expression of emotions are species-specific. Given that faces provide important visual cues for communicating emotional state in both humans and dogs, and that processing of emotions is subject to brain lateralisation, we investigated lateral gaze bias in adult dogs when presented with pictures of expressive human and dog faces. Our analysis revealed clear differences in laterality of eye movements in dogs towards conspecific faces according to the emotional valence of the expressions. Differences were also found towards human faces, but to a lesser extent. For comparative purpose, a similar experiment was also run with 4-year-old children and it was observed that they showed differential processing of facial expressions compared to dogs, suggesting a species-dependent engagement of the right or left hemisphere in processing emotions

Left gaze bias in humans, rhesus monkeys and domestic dogs

While viewing faces, human adults often demonstrate a natural gaze bias towards the left visual field, that is, the right side of the viewee’s face is often inspected first and for longer periods. Using a preferential looking paradigm, we demonstrate that this bias is neither uniquely human nor limited to primates, and provide evidence to help elucidate its biological function within a broader social cognitive framework. We observed that 6-month-old infants showed a wider tendency for left gaze preference towards objects and faces of different species and orientation, while in adults the bias appears only towards upright human faces. Rhesus monkeys showed a left gaze bias towards upright human and monkey faces, but not towards inverted faces. Domestic dogs, however, only demonstrated a left gaze bias towards human faces, but not towards monkey or dog faces, nor to inanimate object images. Our findings suggest that face- and species-sensitive gaze asymmetry is more widespread in the animal kingdom than previously recognised, is not constrained by attentional or scanning bias, and could be shaped by experience to develop adaptive behavioural significance

Dogs (Canis familiaris), but Not Chimpanzees (Pan troglodytes), Understand Imperative Pointing

Chimpanzees routinely follow the gaze of humans to outside targets. However, in most studies using object choice they fail to use communicative gestures (e.g. pointing) to find hidden food. Chimpanzees' failure to do this may be due to several difficulties with this paradigm. They may, for example, misinterpret the gesture as referring to the opaque cup instead of the hidden food. Or perhaps they do not understand informative communicative intentions. In contrast, dogs seem to be skilful in using human communicative cues in the context of finding food, but as of yet there is not much data showing whether they also use pointing in the context of finding non-food objects. Here we directly compare chimpanzees' (N = 20) and dogs' (N = 32) skills in using a communicative gesture directed at a visible object out of reach of the human but within reach of the subject. Pairs of objects were placed in view of and behind the subjects. The task was to retrieve the object the experimenter wanted. To indicate which one she desired, the experimenter pointed imperatively to it and directly rewarded the subject for handing over the correct one. While dogs performed well on this task, chimpanzees failed to identify the referent. Implications for great apes' and dogs' understanding of human communicative intentions are discussed

On Propagation of Excitation Waves in Moving Media: The FitzHugh-Nagumo Model

BACKGROUND: Existence of flows and convection is an essential and integral feature of many excitable media with wave propagation modes, such as blood coagulation or bioreactors. METHODS/RESULTS: Here, propagation of two-dimensional waves is studied in parabolic channel flow of excitable medium of the FitzHugh-Nagumo type. Even if the stream velocity is hundreds of times higher that the wave velocity in motionless medium (), steady propagation of an excitation wave is eventually established. At high stream velocities, the wave does not span the channel from wall to wall, forming isolated excited regions, which we called "restrictons". They are especially easy to observe when the model parameters are close to critical ones, at which waves disappear in still medium. In the subcritical region of parameters, a sufficiently fast stream can result in the survival of excitation moving, as a rule, in the form of "restrictons". For downstream excitation waves, the axial portion of the channel is the most important one in determining their behavior. For upstream waves, the most important region of the channel is the near-wall boundary layers. The roles of transversal diffusion, and of approximate similarity with respect to stream velocity are discussed. CONCLUSIONS: These findings clarify mechanisms of wave propagation and survival in flow

Dog breed differences in visual communication with humans

Domestic dogs (Canis familiaris) have developed a close relationship with humans through the process of domestication. In human-dog interactions, eye contact is a key element of relationship initiation and maintenance. Previous studies have suggested that canine ability to produce human-directed communicative signals is influenced by domestication history, from wolves to dogs, as well as by recent breed selection for particular working purposes. To test the genetic basis for such abilities in purebred dogs, we examined gazing behavior towards humans using two types of behavioral experiments: the `visual contact task' and the `unsolvable task'. A total of 125 dogs participated in the study. Based on the genetic relatedness among breeds subjects were classified into five breed groups: Ancient, Herding, Hunting, Retriever-Mastiff and Working). We found that it took longer time for Ancient breeds to make an eye-contact with humans, and that they gazed at humans for shorter periods of time than any other breed group in the unsolvable situation. Our findings suggest that spontaneous gaze behavior towards humans is associated with genetic similarity to wolves rather than with recent selective pressure to create particular working breeds

The role of cat eye narrowing movements in cat–human communication

Domestic animals are sensitive to human cues that facilitate inter-specific communication, including cues to emotional state. The eyes are important in signalling emotions, with the act of narrowing the eyes appearing to be associated with positive emotional communication in a range of species. This study examines the communicatory significance of a widely reported cat behaviour that involves eye narrowing, referred to as the slow blink sequence. Slow blink sequences typically involve a series of half-blinks followed by either a prolonged eye narrow or an eye closure. Our first experiment revealed that cat half-blinks and eye narrowing occurred more frequently in response to owners’ slow blink stimuli towards their cats (compared to no owner–cat interaction). In a second experiment, this time where an experimenter provided the slow blink stimulus, cats had a higher propensity to approach the experimenter after a slow blink interaction than when they had adopted a neutral expression. Collectively, our results suggest that slow blink sequences may function as a form of positive emotional communication between cats and humans