Messerli Research Institute

In laboratory dogs, aging leads to a decline in various cognitive domains such as learning, memory and behavioural flexibility. However, much less is known about aging in pet dogs, i.e. dogs that are exposed to different home environments by their caregivers. We used tasks on a touch-screen apparatus to detect differences in various cognitive functions across pet Border collies aged from five months to thirteen years. Ninety-five dogs were divided into five age groups, and tested in four tasks: 1) underwater photos vs. drawings discrimination, 2) clip art picture discrimination, 3) inferential reasoning by exclusion and 4) a memory test with a retention interval of six months. The tasks were designed to test three cognitive abilities: visual discrimination learning, logical reasoning, and memory. The total number of sessions to reach criterion and the number of correction trials needed in the two discrimination tasks were compared across age groups. The results showed that both measures increased linearly with age, with dogs aged over three years displaying slower learning and reduced flexibility in comparison to younger dogs. Inferential reasoning ability increased with age, but less than 10% of dogs showed patterns of choice consistent with inference by exclusion. No age effect was found in the long-term memory test. In conclusion, the discrimination learning tests used are suitable to detect cognitive aging in pet dogs, which can serve as a basis for comparison to help diagnose cognition-related problems and as a tool to assist with the development of treatments to delay cognitive decline.

Following human gaze in dogs and human infants can be considered a socially facilitated orientation
response, which in object choice tasks is modulated by human-given ostensive cues. Despite their
similarities to human infants, and extensive skills in reading human cues in foraging contexts, no evidence
that dogs follow gaze into distant space has been found. We re-examined this question, and
additionally whether dogs' propensity to follow gaze was affected by age and/or training to pay attention
to humans. We tested a cross-sectional sample of 145 border collies aged 6 months to 14 years with
different amounts of training over their lives. The dogs' gaze-following response in test and control
conditions before and after training for initiating eye contact with the experimenter was compared with
that of a second group of 13 border collies trained to touch a ball with their paw. Our results provide the
first evidence that dogs can follow human gaze into distant space. Although we found no age effect on
gaze following, the youngest and oldest age groups were more distractible, which resulted in a higher
number of looks in the test and control conditions. Extensive lifelong formal training as well as shortterm
training for eye contact decreased dogs' tendency to follow gaze and increased their duration of
gaze to the face. The reduction in gaze following after training for eye contact cannot be explained by
fatigue or short-term habituation, as in the second group gaze following increased after a different
training of the same length. Training for eye contact created a competing tendency to fixate the face,
which prevented the dogs from following the directional cues. We conclude that following human gaze
into distant space in dogs is modulated by training, which may explain why dogs perform poorly in
comparison to other species in this task.

Aging of attentiveness affects cognitive functions like perception and working memory, which can seriously impact communication between dogs and humans, potentially hindering training and cooperation. Previous studies have revealed that aged laboratory beagles and pet Border collies (BC) show a decline in selective attention. However, much less is known about the aging of attentiveness in pet dogs in general rather than in specific breeds. Using 185 pet dogs (75 BC and 110 dogs of other breeds) divided into three age groups [late adulthood (6-< 8 year), senior (8-< 10 year) and geriatric (≥10 year)], we assessed the progress of aging of attentional capture, sustained and selective attention in older dogs in order to explore if prior results in BC are generalizable and to evaluate the influence of lifelong training on measures of attention. Each dog's lifelong training score (ranging from 0 to 52) was calculated from a questionnaire filled in by the owners listing what kinds of training the dog participated in during its entire life. Dogs were tested in two tasks; the first, measuring attentional capture and sustained attention toward two stimuli (toy and human); and the second, measuring selective attention by means of clicker training for eye contact and finding food on the floor. In the first task, results revealed a significant effect of age but no effect of lifelong training on latency to orient to the stimuli. Duration of looking decreased with age and increased with lifelong training. In the second task, while lifelong training decreased the latency of dogs to form eye contact, aged dogs needed longer to find food. BC did not differ from other dogs in any measures of attention except latency to find food. In conclusion, aged dogs showed a decline in attentional capture and sustained attention demonstrating that these tests are sensitive to detect aging of attentiveness in older pet dogs. Importantly, selective attention remained unchanged with age and lifelong training seemed to delay or reduce the aging of attentiveness, further highlighting the importance of lifelong training in retaining general cognitive functions.

Faces are an important visual category for many taxa, and the human face is no exception to this. Because faces differ in subtle ways and possess many idiosyncratic features, they provide a rich source of perceptual cues. A fair amount of those cues are learned through social interactions and are used for future identification of individual humans. These effects of individual experience can be studied particularly well in hetero-specific face perception. Domestic dogs represent a perfect model in this respect, due to their proved ability to extract important information from the human face in socio-communicative interactions. There is also suggestive evidence that dogs can identify their owner or other familiar human individuals by using visual information from the face. However, most studies have used only dogs&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; looking behavior to examine their visual processing of human faces and it has been demonstrated only that dogs can differentiate between familiar and unknown human faces. Here, we examined the dog&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s ability to discriminate the faces of two familiar persons by active choice (approach and touch). Furthermore, in successive stages of the experiment we investigated how well dogs discriminate humans in different representations by systematically reducing the informational richness and the quality of the stimuli. We found a huge inter-individual and inter-stage variance in performance, indicating differences across dogs in their learning ability as well as their selection of discriminative cues. On a group level, the performance of dogs significantly decreased when they were presented with pictures of human heads after having learned to discriminate the real heads, and when - after relearning - confronted with the same pictures showing only the inner parts of the heads. However, as two dogs quickly mastered all stages, we conclude that dogs are in principle able to discriminate people on the basis of visual information from their faces and by making active choices.

Dogs are exceptionally successful at interpreting human pointing gestures to locate food hidden in one of two containers. However, it has repeatedly been questioned whether dogs rely on the pointing gesture or their success is increased by subtle cues from their human handler. In two experiments we used a standard two-way object-choice task to focus on this potential Clever Hans effect. We investigated if and how owners' knowledge and beliefs influenced their dogs' performance. In two experiments, as is typical in such pointing tasks, the owners sat behind their dogs, in close auditory and tactile contact with them. In Experiment 1, we systematically manipulated the owners' knowledge of whether or not their dog should follow the pointing gesture, but at the same time instructed the owners to refrain from influencing the choice of their dog. We found no influence of subtle cues from the owners, if indeed they existed: dogs in the different groups followed the pointing uniformly. Furthermore, in the absence of pointing dogs chose randomly, even though the owners had been informed about the location of the reward. In Experiment 2, owners were instructed to actively influence the choice of their dogs, and they, indeed, succeeded in sending their dogs to the container they believed to be baited. However, their influence was significantly weaker if the experimenter had previously pointed to the other location. Overall the pointing gesture seems to have a strong effect on the choice of dogs in an object-choice task. Pointing can lead the dogs to success without help from their owners as well as it can counteract clear directional instructions provided by the owners.