Skill in expert dogs

The motor control of novice participants is often cognitively demanding and susceptible to interference by other tasks. As people develop expertise, their motor control becomes less susceptible to interference from other tasks. Researchers propose a transition in human motor skill from active control to automaticity. This progression may also be the case with nonhuman animals. Differences in performance characteristics between expert, advanced, intermediate, and novice dogs competing in the sport of agility were investigated. There were statistically significant differences between dogs of varying competitive levels in speed, motor control, and signal detections suggestive of increasing motor control automaticity in highly skilled, or expert, dogs. The largest sequential motor control difference was between novice and intermediate dogs, d = .96, whereas the largest sequential signal detection difference was between advanced and expert dogs, d = .90. These findings have two significant implications for expertise researchers: first, the observed similarities between dogs and humans may enable dogs to be used as expert models; and second, expertise science and methods may be profitably employed in the future to create more proficient canine workers.     

Gaze-following behind barriers in domestic dogs

Although gaze-following abilities have been demonstrated in a wide range of species, so far no clear evidence has been available for dogs. In the current study, we examined whether dogs follow human gaze behind an opaque barrier in two different contexts, in a foraging situation and in a non-foraging situation (food involved vs. food not involved in the situation). We assumed that dogs will spontaneously follow the human gaze and that the foraging context will have a positive effect on dogs’ gaze-following behaviour by causing an expectation in the dogs that food might be hidden somewhere in the room and might be communicated by the experimenter. This expectation presumably positively affects their motivational and attentional state. Here, we report that dogs show evidence of spontaneous gaze-following behind barriers in both situations. According to our findings, the dogs gazed earlier at the barrier in the indicated direction in both contexts. However, as we expected, the context also has some effect on dogs’ gaze-following behaviour, as more dogs gazed behind the barrier in the indicated direction in the foraging situation. The present results also support the idea that gaze-following is a characteristic skill in mammals which may more easily emerge in certain functional contexts.     

One-trial cardiac conditioning in dogs

Our interest in cardiovascular conditioning, particularly the fact that conditional tachycardia has been observed in many dogs after only one or two combinations of conditional and unconditional stimuli, led us to investigate conditioning using a single application of an unconditional stimulus. Initially we studied the effect of orienting stimuli (soft tones) on the heart rate in 9 dogs. After 30–100 presentations of the tones alone, each dog received on one occasion a 25-volt shock (sufficient to cause yelping and struggling) to a leg as unconditional stimulus immediately following a tone. Thereafter 30–100 additional tones were presented with no further shock. Little or no heart rate change occurred during the orienting tones (before shock). Three types of cardiac changes occurred during experimental sessions after the shock: 1) Increased heart rate during the tones in 5 dogs; 2) Generalized lowering of heart rate during all experimental sessions after shock in 4 dogs; 3) Electrocardiographic changes during tones in 3 of the dogs also showing the generalized decrease in heart rate. No motor flexion conditional reflexes developed. Tones an octave different in pitch from the one associated with the shock also caused approximately the same heart rate changes, indicating lack of differentiation. This one-trial cardiac conditioning persisted after the single conditioning trial for more than a month in 2 dogs and for at least 3 to 5 sessions in the other dogs.     

Biochemistry of nervous dogs

Previous behavioral studies on a nervous strain of pointer dogs have demonstrated genetic as well as environmental components in the nervous trait. Behaviorally these animals are extremely hypervigilant, with an apparent low threshold to fear and show strong avoidance of humans. In addition, the nervous E strain dogs show an unusually high degree of sensitivity to the mange mite. These observations led to the initiation of studies to determine whether differences exist between the normal A strain and the E strain of dogs at the biochemical level. Although a number of biochemical parameters examined have shown no statistically significant difference between the two strains, the modification of serum creatine phosphokinase (CPK) activity in response to various types of stress does differ as a function of strain—the nervous dogs being less, not more, responsive than the healthy dogs. When not specifically subjected to stress the serum CPK levels in both strains were highly related to age. Significant differences between strains also have been demonstrated in the cerebrospinal fluid acetyl cholinesterase activity levels in older animals. Tryptophan loading experiments, conducted in the presence and absence of the monoamine oxidase inhibitor, tranylcypromine, resulted in no readily observable behavioral modification of either strain and the response of the cerebrospinal fluid 5-hydroxyindoleacetic acid levels was similar for the two strains.     

Attachment between humans and dogs

The special relationship that dogs have developed with humans has been studied not only from the social sciences perspective, but also from the perspectives of psychology and human medicine. Recently, in cognitive science, it has been suggested that dogs may have acquired the superior cognitive ability to communicate with humans, particularly using human-like visual cues during evolution, and that emotional bonding has developed between humans and dogs by means of similar social cues. This article discusses the biological aspects of human-dog attachment. Attachment requires the distinction of a specific figure using species-specific social cues and specific responses to the figure, brought about by neuroendocrinological homeostatic functions as well as behavioral aspects. It has been shown that dogs can distinguish a particular human figure (e.g. the owner) and exhibit specific autonomic reactions. Moreover, when dogs gaze at their owners, the latter's urinary oxytocin levels increase after the interaction. This understanding of the biological aspect of interspecies attachment suggests the possible elements that form the basis of cross-species empathy and the development of evolutionary cognitive abilities that may depend on not merely their genetic dendrogram.     

Operant performance patterns of normal and nervous water-deprived dogs

Previous studies have shown that most food-deprived genetically nervous pointer dogs fail to learn a bar-pressing response for food reward and those which do learn are erratic in bar pressing compared to genetically normal pointer dogs which usually learn rapidly and perform well. Benzodiazepine drugs facilitate learning and performance of the responses in nervous dogs. The present study aimed at finding whether a stronger drive producing state, such as water deprivation, would facilitate learning and performance in even severely nervous dogs. Eight normal line and 7 nervous line dogs successfully learned to perform well a paddle-pressing response which activates a valve releasing water into a drinking pan. One disturbed dog of each line did not learn successfully. Behavior shaping was about as easy and as rapid in nervous line dogs as in normals. Nervous line dogs tended to be as consistent in responding. However, response rates of nervous line dogs averaged about two-thirds those of normal line dogs, the slowed rate of responses being taken up mostly in excessive, rather stereotyped, licking of the water pan. Response rates correlated well with degree of nervousness as measured on independent well standardized behavior tests. This behavior seems to add another dimension to the characterization of the nervousness of these “spooky” pointer dogs.     

Context specificity of inhibitory control in dogs

Across three experiments, we explored whether a dog’s capacity for inhibitory control is stable or variable across decision-making contexts. In the social task, dogs were first exposed to the reputations of a stingy experimenter that never shared food and a generous experimenter who always shared food. In subsequent test trials, dogs were required to avoid approaching the stingy experimenter when this individual offered (but withheld) a higher-value reward than the generous experimenter did. In the A-not-B task, dogs were required to inhibit searching for food in a previously rewarded location after witnessing the food being moved from this location to a novel hiding place. In the cylinder task, dogs were required to resist approaching visible food directly (because it was behind a transparent barrier), in favor of a detour reaching response. Overall, dogs exhibited inhibitory control in all three tasks. However, individual scores were not correlated between tasks, suggesting that context has a large effect on dogs’ behavior. This result mirrors studies of humans, which have highlighted intra-individual variation in inhibitory control as a function of the decision-making context. Lastly, we observed a correlation between a subject’s age and performance on the cylinder task, corroborating previous observations of age-related decline in dogs’ executive function.     

The role of police dogs as companions and working partners

Written responses to a questionnaire by 255 officers who used canines in police work were assessed. Almost all officers frequently played with, talked to, petted, and brushed their dogs and believed the dogs benefitted their health and well-being. Officers whose dogs slept indoors, often in the same bedroom, generally said they loved their dogs and they described their dogs as calm rather than active, as indicated by a multiple correspondence analysis. These 96 officers more than the 154 officers whose dogs slept outdoors or in kennels also planned to remain in canine work. Although departments often assumed responsibility for purchasing the dogs, the more experienced officers usually were involved in the final selection of dogs (logistic regression: p < .0001). Compared with 94 officers not involved in selecting their dogs, 106 officers with a specific role in selecting their dogs planned to stay in canine work, as shown by a multiple correspondence analysis. They believed the dogs had saved their lives (p < .01). Over-all, officers reported spending 4.1 hr. on-duty and 2.9 hr. off-duty per week training their dogs, and also played with them for 6.5 hr. per week, assuring a regular pattern of exercise for the officers. Virtually all officers valued canine service and believed the dogs enhanced the department's effectiveness. This study showed that both close companionship with the dog and involvement in selecting the dog were associated both with satisfaction with the dog and with working as a canine officer.     

How two word-trained dogs integrate pointing and naming

Two word-trained dogs were presented with acts of reference in which a human pointed, named objects, or simultaneously did both. The question was whether these dogs would assume co-reference of pointing and naming and thus pick the pointed-to object. Results show that the dogs did indeed assume co-reference of pointing and naming in order to determine the reference of a spoken word, but they did so only when pointing was not in conflict with their previous word knowledge. When pointing and a spoken word conflicted, the dogs preferentially fetched the object by name. This is not surprising since they are trained to fetch objects by name. However, interestingly, in these conflict conditions, the dogs fetched the named objects only after they had initially approached the pointed-to object. We suggest that this shows that the word-trained dogs interpret pointing as a spatial directive, which they integrate into the fetching game, presumably assuming that pointing is relevant to finding the requested object.     

Origins of fear of dogs in adults and children: the role of conditioning processes and prior familiarity with dogs.

One hundred adults and 30 children completed questionnaires to investigate fear of dogs. Dog fearful adults asked to recall the origins of their fear reported classical conditioning experiences more frequently than vicarious acquisition or informational transmission. Overall, however, there was no difference in the frequency of attacks reported by the fearful and non-fearful groups. Significantly more fearful than non-fearful adults reported little contact with dogs prior to the onset of their fear which suggests that early non-eventful exposure to dogs may prevent a conditioning event from producing a dog phobia. Most adults reported that their fear began in childhood, and dog fear were more frequently reported by children than by adults. In the aggregate, however, dog-fearful adults and children differed in several ways; children were more likely than adults to report having received warnings about dogs, but also to recognize the potential attractiveness of a friendly dog. Unlike dog-fearful children, dog-fearful adults reported many other fears in addition to their fear of dogs. A better understanding of fear of dogs in adults may depend on discovering why some dog-fearful children, but not others, apparently lose their fear of dogs as they become older.     

The rehabilitation of genetically nervous dogs

Aware that intensive efforts to rehabilitate half of split litters from a nervous strain of Pointers through daily human contact have been unsuccessful, the authors designed this study to determine if a radically different approach utilizing the natural interest for birds and hunting which most Pointers possess would be a bridge to normalcy so that dogs genetically prone to nervous behavior could be rehabilitated. Five nervous and three normal dogs approaching young adulthood were gradually desensitized to open areas, live quail, gun reports and humans—all of which usually produce catatonic freezing, hyper-startle and strong avoidance behavior in the nervous animals. Through a “naturalistic” approach in the framework of the Pointers’ non-laboratory ecological niche using graduated techniques, reciprocally competitive responses and social facilitation, which are described, all the nervous dogs that showed an original “interest” for the qua.l were trained as successful hunted dogs, not obviously different in final performance from their normal kennel mates. Although the nervous dogs overcame their freezing, hyper-startle and human aversion while hunting, generalization did not extend sufficiently to normalize standard behavior test scores obtained under laboratory conditions. These remained at their prerehabilitation level, raising the question of the adequacy of the behavioi tests conducted in a laboratory environment. This appears to be related to the limitations often seen in psychotherapeutic efforts.     

Visual event-related potentials of dogs: a non-invasive electroencephalography study

Previously, social and cognitive abilities of dogs have been studied within behavioral experiments, but the neural processing underlying the cognitive events remains to be clarified. Here, we employed completely non-invasive scalp-electroencephalography in studying the neural correlates of the visual cognition of dogs. We measured visual event-related potentials (ERPs) of eight dogs while they observed images of dog and human faces presented on a computer screen. The dogs were trained to lie still with positive operant conditioning, and they were neither mechanically restrained nor sedated during the measurements. The ERPs corresponding to early visual processing of dogs were detectable at 75–100 ms from the stimulus onset in individual dogs, and the group-level data of the 8 dogs differed significantly from zero bilaterally at around 75 ms at the most posterior sensors. Additionally, we detected differences between the responses to human and dog faces in the posterior sensors at 75–100 ms and in the anterior sensors at 350–400 ms. To our knowledge, this is the first illustration of completely non-invasively measured visual brain responses both in individual dogs and within a group-level study, using ecologically valid visual stimuli. The results of the present study validate the feasibility of non-invasive ERP measurements in studies with dogs, and the study is expected to pave the way for further neurocognitive studies in dogs.     

An exploratory analysis of head-tilting in dogs

Animal Cognition - Little is known about head-tilts in dogs. Based on previous investigations on the head turning and the lateralised brain pattern of human speech processing in dogs, we...     

Human left-sided cradling preferences for dogs

Photographs of men and women holding dogs were analyzed for side-holding preferences. A significant majority of women in dog-themed magazines held dogs on their left sides, similar to reports of women holding infants. Men did not show the same left-sided preference, which is also consistent with other studies. The implications of these results for various hypotheses about infant cradling behavior were discussed.     

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.     

Domestic dogs conceal auditory but not visual information from others

A number of studies have shown that dogs are sensitive to a human’s perspective, but it remains unclear whether they use an egocentric strategy to assess what humans perceive. We investigated whether dogs know what a human can see and hear, even when the dogs themselves are unable to see the human. Dogs faced a task in which forbidden food was placed in a tunnel that they could retrieve by using their paw. Whereas the dogs could not see the experimenter during their food retrieval attempts, the experimenter could potentially see the dog’s paw. In the first experiment, dogs could choose between an opaque and a transparent side of the tunnel, and in the second experiment, they could choose between a silent and a noisy approach to the tunnel. The results showed that dogs preferred a silent approach to forbidden food but they did not hide their approach when they could not see a human present. We conclude that dogs probably rely on what they themselves can perceive when they assess what the human can see and hear.     

Domestication has not affected the understanding of means-end connections in dogs

Recent studies have revealed that dogs often perform well in cognitive tasks in the social domain, but rather poorly in the physical domain. This dichotomy has led to the hypothesis that the domestication process might have enhanced the social cognitive skills of dogs (Hare et al. in Science 298:1634-1636, 2002; Miklósi et al. in Curr Biol 13:763-766, 2003) but at the same time had a detrimental effect on their physical cognition (Frank in Z Tierpsychol 5:389-399, 1980). Despite the recent interest in dog cognition and especially the effects of domestication, the latter hypothesis has hardly been tested and we lack detailed knowledge of the physical understanding of wolves in comparison with dogs. Here, we set out to examine whether adult wolves and dogs rely on means-end connections using the string-pulling task, to test the prediction that wolves would perform better than dogs in such a task of physical cognition. We found that at the group level, dogs were more prone to commit the proximity error, while the wolves showed a stronger side bias. Neither wolves nor dogs showed an instantaneous understanding of means-end connection, but made different mistakes. Thus, the performance of the wolves and dogs in this string-pulling task did not confirm that domestication has affected the physical cognition of dogs.     

Minding the gap: spatial perseveration error in dogs

We investigated a combination of perseveration and detour behaviour in 50 domestic dogs (Canis familiaris). They were required to make a detour through a gap at one end of a straight barrier in order to reach a target. After one, two, three or four repeats, the gap was moved to the opposite end of the barrier, and the detour behaviour of the dogs was recorded. Although the dogs could solve simple detour tasks (80% correct in the first trial), they committed a perseveration error of following the previously learned route despite the clearly visible change in the location of the gap. This ‘misbehaviour’ occurred in 29 of 30 dogs after only two learning trials. They never reached a 100% correct performance level again even after four runs through the second gap location. The results suggest that dogs are reluctant to unlearn acquired spatial motor responses and reinforced navigation, which has important implications for experimental design, everyday dog training and our understanding of their mental capacities.     

Deferred imitation and declarative memory in domestic dogs

This study demonstrates for the first time deferred imitation of novel actions in dogs (Canis familiaris) with retention intervals of 1.5 min and memory of familiar actions with intervals ranging from 0.40 to 10 min. Eight dogs were trained using the ‘Do as I do’ method to match their own behaviour to actions displayed by a human demonstrator. They were then trained to wait for a short interval to elapse before they were allowed to show the previously demonstrated action. The dogs were then tested for memory of the demonstrated behaviour in various conditions, also with the so-called two-action procedure and in a control condition without demonstration. Dogs were typically able to reproduce familiar actions after intervals as long as 10 min, even if distracted by different activities during the retention interval and were able to match their behaviour to the demonstration of a novel action after a delay of 1 min. In the two-action procedure, dogs were typically able to imitate the novel demonstrated behaviour after retention intervals of 1.5 min. The ability to encode and recall an action after a delay implies that facilitative processes cannot exhaustively explain the observed behavioural similarity and that dogs’ imitative abilities are rather based on an enduring mental representation of the demonstration. Furthermore, the ability to imitate a novel action after a delay without previous practice suggests presence of declarative memory in dogs.     

Adaptive spatial working memory assessments for aging pet dogs

Assessments for spatial working memory (SWM) in pet dogs that can detect age-related cognitive deficits in a single session may aid in diagnosing canine dementia and may facilitate translational research on Alzheimer’s disease in humans. Adaptive testing procedures are widely used in single-session assessments for humans with diverse cognitive abilities. In this study, we designed and deployed two up-down staircase assessments for SWM in which 26 pet dogs were required to recall the location of a treat hidden behind one of two identical boxes following delays of variable length. In the first experiment, performance tended to decline with age but few dogs completed the test (n?=?10). However, all of the dogs that participated in the second experiment (n?=?24) completed the assessment and provided reliable evidence of learning and retaining the task. Delay length and age significantly predicted performance supporting the validity of this assessment. The relationships between age and performance were described by inverted U-shaped functions as both old and young dogs displayed deficits in weighted cumulative-scores and trial-by-trial performance. Thus, SWM in pet dogs may develop until midlife and decline thereafter. Exploratory analyses of non-mnemonic fixation strategies, sustained engagement, inhibitory control, and potential improvements for future SWM assessments which adopt this paradigm are also discussed.