Dogs (Canis lupus familiaris) are susceptible to the Kanizsa’s triangle illusion

Animal Cognition - The ability to complete partially missing contours is widespread across the animal kingdom, but whether this extends to dogs is still unknown. To address this gap in knowledge,...     

The effect of experience and of dots’ density and duration on the detection of coherent motion in dogs

Knowledge about the mechanisms underlying canine vision is far from being exhaustive, especially that concerning post-retinal elaboration. One aspect that has received little attention is motion perception, and in spite of the common belief that dogs are extremely apt at detecting moving stimuli, there is no scientific support for such an assumption. In fact, we recently showed that dogs have higher thresholds than humans for coherent motion detection (Kanizsar et al. in Sci Rep UK 7:11259, 2017). This term refers to the ability of the visual system to perceive several units moving in the same direction, as one coherently moving global unit. Coherent motion perception is commonly investigated using random dot displays, containing variable proportions of coherently moving dots. Here, we investigated the relative contribution of local and global integration mechanisms for coherent motion perception, and changes in detection thresholds as a result of repeated exposure to the experimental stimuli. Dogs who had been involved in the previous study were given a conditioned discrimination task, in which we systematically manipulated dot density and duration and, eventually, re-assessed our subjects’ threshold after extensive exposure to the stimuli. Decreasing dot duration impacted on dogs’ accuracy in detecting coherent motion only at very low duration values, revealing the efficacy of local integration mechanisms. Density impacted on dogs’ accuracy in a linear fashion, indicating less efficient global integration. There was limited evidence of improvement in the re-assessment but, with an average threshold at re-assessment of 29%, dogs’ ability to detect coherent motion remains much poorer than that of humans.     

Dogs’ ability to follow temporarily invisible moving objects: the ability to track and expect is shaped by experience

Animal Cognition - Visually tracking a moving object, even if it becomes temporarily invisible, is an important skill for animals living in complex environments. However, this ability has not been...     

Dogs (Canis familiaris) recognise our faces in photographs: implications for existing and future research

Animal Cognition - Dogs are an ideal species to investigate phylogenetic and ontogenetic factors contributing to face recognition. Previous research has found that dogs can recognise their owner...     

Hierarchical stimulus processing by dogs (Canis familiaris)

The purpose of this study was to assess the visual processing of global and local levels of hierarchical stimuli in domestic dogs. Fourteen dogs were trained to recognise a compound stimulus in a simultaneous conditioned discrimination procedure and were then tested for their local/global preference in a discrimination test. As a group, dogs showed a non-significant trend for global precedence, although large inter-individual variability was observed. Choices in the test were not affected by either dogs’ sex or the type of stimulus used for training. However, the less time a dog took to complete the discrimination training phase, the higher the probability that it chose the global level of test stimulus. Moreover, dogs that showed a clear preference for the global level in the test were significantly less likely to show positional responses during discrimination training. These differences in the speed of acquisition and response patterns may reflect individual differences in the cognitive requirements during discrimination training. The individual variability in global/local precedence suggests that experience in using visual information may be more important than predisposition in determining global/local processing in dogs.     

Impact of Traumatic Life Events in a Community Sample of Toddlers

Toddlers may be at particularly high risk for a number of psychiatric, developmental and neurobiological consequences in the aftermath of trauma. The social and emotional impact of potentially traumatic life events experienced between 6 and 36-months of age was assessed in an epidemiological birth cohort of 18- to 36-month-olds from the Greater New Haven Area. Event-exposed toddlers evidenced greater symptom severity on the ITSEA Internalizing, Externalizing, Dysregulation, Atypical and Maladaptive scales, as well on the CBCL Internalizing and Externalizing scales than those not exposed. Approximately one-fifth of event-exposed toddlers were reported by their parents to have experienced a dramatic change in functioning following the event, and were described as experiencing higher levels of symptoms consistent with Post-Traumatic Stress Disorder (PTSD), namely re-experiencing and arousal, than exposed toddlers whose parents did not report a change in their functioning. Implications for clinicians and child care providers working with toddlers and their parents are discussed.     

I know a dog when I see one: dogs (Canis familiaris) recognize dogs from videos

Animal Cognition - Several aspects of dogs’ visual and social cognition have been explored using bi-dimensional representations of other dogs. It remains unclear, however, if dogs do...     

Recognition of human faces by dogs (<Emphasis Type="Italic">Canis familiaris</Emphasis>) requires visibility of head contour

Researchers have suggested that dogs are able to recognise human faces, but conclusive evidence has yet to be found. Experiment 1 of this study investigated whether dogs can recognise humans using visual information from the face/head region, and whether this also occurs in conditions of suboptimal visibility of the face. Dogs were presented with their owner’s and a stranger’s heads, protruding through openings of an apparatus in opposite parts of the experimental setting. Presentations occurred in conditions of either optimal or suboptimal visibility; the latter featured non-frontal orientation, uneven illumination and invisibility of outer contours of the heads. Instances where dogs approached their owners with a higher frequency than predicted by chance were considered evidence of recognition. This occurred only in the optimal condition. With a similar paradigm, Experiment 2 investigated which of the alterations in visibility that characterised the suboptimal condition accounted for dogs’ inability to recognise owners. Dogs approached their owners more frequently than predicted by chance if outer head contours were visible, but not if heads were either frontally oriented or evenly illuminated. Moreover, male dogs were slightly better at recognition than females. These findings represent the first clear demonstration that dogs can recognise human faces and that outer face elements are crucial for such a task, complementing previous research on human face processing in dogs. Parallels with face recognition abilities observed in other animal species, as well as with human infants, point to the relevance of these results from a comparative standpoint.     

Meowing dogs: can dogs recognize cats in a cross-modal violation of expectancy task (Canis familiaris)?

Animal Cognition - Dogs can recognize conspecifics in cross-modal audio–video presentations. In this paper, we aimed at exploring if such capability extends to the recognition of cats, and...     

Sex differences in dogs’ social learning of spatial information

We used a modified version of the Do as I Do paradigm to investigate dogs’ preference and flexibility in the acquisition of different types of spatial information in social learning situations. When required to match the location of the demonstration, dogs (N = 16) preferentially relied on allocentric information, i.e., the relationship between the location of the demonstration and the various objects surrounding it. However, when allocentric cues were inadequate to solve the task, dogs learned to rely on egocentric information, i.e., the direction—left/right—taken by the human demonstrator. The ease of resorting to the non-preferred egocentric strategy was sex-dependent with males acquiring the egocentric strategy in fewer trials than females. This study shows that dogs rely preferentially on allocentric cues when recalling socially acquired spatial information. However, they are impressively flexible in switching to egocentric strategies according to the task requirements. Whether preference for the allocentric strategy in processing spatial information is embedded in the nature of social learning or restricted to our paradigm is an open question. This study also supports the idea that sex differences in cognitive domains are widespread among mammals and calls for further investigations aimed at shedding light on the evolution, function and mechanisms of such differences.