The development of problem-solving abilities in a population of candidate detection dogs (Canis familiaris)

Body Awareness Does Not Need a Pedigree: Mixed-Breed Dogs Rely More on Self-Representation Than Social Learning in a Spatial Task

Body awareness allows the individual to negotiate spatial tasks by referencing their own body. Here, we tested whether biologically meaningful factors, such as an alternative solution (detour around an obstacle) and learning from a human demonstrator, would affect dogs' reliance on their body size in an aperture test. We hypothesized that the dogs would choose the socially reinforced solution over a shortcut, and they would choose the shortcut when the opening was comfortably large. We tested N = 45 adult, mixed-breed dogs, by using a 3 m long, transparent fence. The dogs had three trials with closed doors and then three trials with either a small (but passable) or a large open door. In the demonstration group the experimenter performed a detour before the first three trials, then we opened the large door. The dogs preferred the shortcut, where they relied on body awareness, as they either hesitated or opted for a detour when the small door was open. The dogs who watched the demonstration for longer in trial 3 chose the door less often in trial 4, which indicates social learning. By testing mixed-breed dogs, our results are minimally influenced by functional breed selection and serve as valuable baseline for testing complex socio-cognitive traits in companion dogs.

Dog-Owner Relationship and Its Association with Social Cognition in French Bulldogs

Our understanding of social cognition in brachycephalic dog breeds is limited. This study focused specifically on French Bulldogs and hypothesized that a closer relationship between dog and owner would improve the dogs' understanding of nonverbal cues, particularly pointing gestures. To investigate this, we tested twenty-six dogs and their owners in a two-way object choice test in which the familiar person pointed to the bowl. As understanding of pointing gestures is influenced by human-animal interaction, we used the Monash Dog Owner Relationship Scale (MDORS) to assess various aspects of the dog-owner relationship, including dog-owner interaction, emotional closeness, and negative aspects of dog ownership and measured salivary oxytocin levels. This study examined the dogs' correct choices and their straight approach patterns to a reward bowl. Several factors influenced the two measures of social cognition, such as the age and sex of the dog, dog-owner interaction, emotional closeness, and the choice time (time it took the dog to reach the reward bowl), but also that neutered dogs and those with no training history showed better cognitive performance. We found a very high number of correct choices, which could be attributed to the owners' high scores on the dog-owner interaction scale. Oxytocin showed no direct effect on these measures. To increase the generalizability of the results, we suggest future studies focus on more than one breed to capture the temporal development of the owner-dog relationship and social cognitive abilities.

Methods of behavioral testing in dogs: a scoping review and analysis of test stimuli

Background

Behavioral testing is widely used to measure individual differences in behavior and cognition among dogs and predict underlying psychological traits. However, the diverse applications, methodological variability, and lack of standardization in canine behavioral testing has posed challenges for researchers and practitioners seeking to use these tests. To address these complexities, this review sought to synthesize and describe behavioral testing methods by creating a framework that uses a "dog-centric" perspective to categorize the test stimuli used to elicit responses from dogs.

Methods

A scoping review was conducted to identify scientific literature that has reported behavioral testing to assess psychological traits in dogs. Five online databases were systematically searched. Following this, an inductive content analysis was conducted to evaluate and summarize the behavioral testing methods in the literature.

Results

A total of 392 publications met the selection criteria and were included in the analysis, collectively reporting 2,362 behavioral tests. These tests were individually evaluated and categorized. Our content analysis distinguished 29 subcategories of behavioral testing stimuli that have been used, grouped into three major categories: human-oriented stimuli; environmental stimuli; and motivator-oriented stimuli.

Conclusion

Despite the methodological heterogeneity observed across behavioral testing methods, our study identified commonalities in many of the stimuli used in test protocols. The resulting framework provides a practical overview of published behavioral tests and their applications, which may assist researchers in selecting and designing appropriate tests for their purposes.

Longitudinal evidence for the emergence of multiple intelligences in assistance dog puppies

Cognitive test batteries suggest that adult dogs have different types of cognitive abilities that vary independently. In the current study, we tested puppies repeatedly over a crucial period of development to explore the timing and rate at which these different cognitive skills develop. Service dog puppies (n = 113), raised using two different socialization strategies, were either tested longitudinally (n =91) or at a single time point (n = 22). Subjects tested longitudinally participated in the battery every two weeks during and just beyond their final period of rapid brain growth (from approximately 8-20 weeks of age). Control puppies only participated in the test battery once, which allowed us to evaluate the impact of repeated testing. In support of the multiple intelligences hypothesis (MIH), cognitive skills emerged at different points across the testing period, not simultaneously. Maturational patterns also varied between cognitive skills, with puppies showing adult-like performance on some tasks only weeks after a skill emerged, while never achieving adult performance in others. Differences in rearing strategy did not lead to differences in developmental patterns while, in some cases, repeated testing did. Overall, our findings provide strong support for the MIH by demonstrating differentiated development across the cognitive abilities tested.

Cooperative but Dependent-Functional Breed Selection in Dogs Influences Human-Directed Gazing in a Difficult Object-Manipulation Task

It is still largely unknown to what extent domestication, ancestry, or recent functional selection are responsible for the behavioral differences in whether dogs look back to a human when presented with a difficult task. Here, we tested whether this ubiquitous human-related response of companion dogs would appear differently in subjects that were selected for either cooperative or independent work tasks. We tested N = 71 dogs from 18 cooperative and 18 independent breeds. Subjects learned in a five-trial warming-up phase that they could easily obtain the reward from a container. In trial six, the reward became impossible to take out from the locked container. When the task was easy, both breed groups behaved similarly, and their readiness to approach the container did not differ between the last 'solvable' and the subsequent 'unsolvable' trial. Task focus, looking at the container, touching the container for the first time, or interacting with the container with a paw or nose did not differ between the breed groups, indicating that their persistence in problem solving was similar. However, in the 'unsolvable' trial, cooperative dogs alternated their gaze more often between the container and the humans than the independent dogs did. The frequency of looking back was also higher in cooperative dogs than in the independent breeds. These are the first empirical results that suggest, in a balanced, representative sample of breeds, that the selection for different levels of cooperativity in working dogs could also affect their human-dependent behavior in a generic problem-solving situation.

A preliminary analysis of the effect of individual differences on cognitive performance in young companion dogs

Many factors influence cognitive performance in dogs, including breed, temperament, rearing history, and training. Studies in working dog populations have demonstrated age-related improvements in cognitive task performance across the first years of development. However, the effect of certain factors, such as age, sex, and temperament, on cognitive performance in puppies has yet to be evaluated in a more diverse population of companion dogs. In this study, companion dogs under 12 months of age were tested once on two tasks purported to measure aspects of executive function: the delayed-search task (DST) and the detour reversal task (DRT). Owners also filled out the Canine Behavioral Assessment and Research Questionnaire (C-BARQ) to evaluate how temperament influenced task performance. Contrary to prior research, performance did not improve with age on either task. However, the lack of age effects was likely the result of small sample sizes and individual differences across other factors influencing performance. Specifically, temperament differences as measured by the C-BARQ subscales for nonsocial fear and excitability predicted task performance on the DST, but the effect of temperament on task performance differed between males and females. Excitability also predicted performance on the DRT, but the effect depended on the age of the dog. In addition, no correlations were observed between task measures, indicating a lack of construct validity. Overall, these findings provide a preliminary analysis of factors that appear to influence cognitive task performance in young companion dogs and highlight suggestions for future research evaluating the impact of individual differences on cognitive performance.

Executive Functions as Measured by the Dog Executive Function Scale (DEFS) over the Lifespan of Dogs

Executive Functions (EFs) are needed for effortful self-regulation of behaviour and are known to change over the lifespan in humans. In domestic dogs, EFs can be assessed through behavioural rating scales, such as the Dog Executive Function Scale (DEFS). The primary aim of this study was to investigate whether the DEFS, developed initially using a sample of adult dogs, can be used in juvenile (<1 year) and senior (>8 years) dogs. Confirmatory factor analysis of a juvenile and senior dog sample led to good model fit indices, indicating that juvenile and senior dogs' EF structure follows the same functional organisation as found in the DEFS. The secondary aim was to analyse the lifespan development of EFs. Analysis of subscale scores revealed multifaceted relationships with age for four subscales. Working Memory and Attention Towards Owner showed the u-shaped curve traditionally associated with the lifespan development of EFs. Forms of inhibition showed complex associations with age, i.e., Delay Inhibition declined in aging and Motor Regulation increased during aging. Training history and Working Status influenced performance independent of age. More highly trained dogs and working dogs exhibited higher EF skills. Training history appeared more important for EF in non-working dogs than working dogs, perhaps because all working dogs receive a high level of training.

Defining the Characteristics of Successful Biosecurity Scent Detection Dogs

To perform their role effectively, scent detection dogs require certain characteristics. Identifying these characteristics will inform the selection of prospective dogs and preferred approaches to their training. The current study drew upon the perspectives of industry stakeholders to identify the behavioural traits considered relevant for detection dogs in biosecurity screening roles. Dog handlers, trainers, and supervisors (n = 25) in Australian biosecurity operations participated in focus group interviews to determine the perceived characteristics that, in their experience, influence detection performance. Their descriptions were used to create a questionnaire which was then administered to handlers to assess the working behaviours of current biosecurity dogs. Responses were collected for 88% of the operational dogs (n = 36). An exploratory factor analysis revealed seven tentative dimensions: search motivation, emotional stability, search arousal, food motivation, play motivation, search independence, and search focus. Search motivation and search arousal were both positively associated with handler ratings of detection performance (p ≤ 0.006). In general, biosecurity dogs were scored consistently high in ratings of search motivation, emotional stability, and food motivation. Our approach has advanced our understanding of the working behaviours and characteristic profile of biosecurity detector dogs and will be used to inform candidate selection processes.

Breed differences in social cognition, inhibitory control, and spatial problem-solving ability in the domestic dog (Canis familiaris)

The extraordinary genetic and behavioural diversity of dog breeds provides a unique opportunity for investigating the heritability of cognitive traits, such as problem-solving ability, social cognition, inhibitory control, and memory. Previous studies have mainly investigated cognitive differences between breed groups, and information on individual dog breeds is scarce. As a result, findings are often contradictory and inconsistent. The aim of this study was to provide more clarity on between-breed differences of cognitive traits in dogs. We examined the performance of 13 dog breeds (N = 1002 dogs) in a standardized test battery. Significant breed differences were found for understanding of human communicative gestures, following a human's misleading gesture, spatial problem-solving ability in a V-detour task, inhibitory control in a cylinder test, and persistence and human-directed behaviour during an unsolvable task. Breeds also differed significantly in their behaviour towards an unfamiliar person, activity level, and exploration of a novel environment. No significant differences were identified in tasks measuring memory or logical reasoning. Breed differences thus emerged mainly in tasks measuring social cognition, problem-solving, and inhibitory control. Our results suggest that these traits may have come under diversifying artificial selection in different breeds. These results provide a deeper understanding on breed-specific traits in dogs.

Environmental risk factors in puppies and kittens for developing chronic disorders in adulthood: A call for research on developmental programming

Many dogs and cats are affected by chronic diseases that significantly impact their health and welfare and relationships with humans. Some of these diseases can be challenging to treat, and a better understanding of early-life risk factors for diseases occurring in adulthood is key to improving preventive veterinary care and husbandry practices. This article reviews early-life risk factors for obesity and chronic enteropathy, and for chronic behavioral problems, which can also be intractable with life-changing consequences. Aspects of early life in puppies and kittens that can impact the risk of adult disorders include maternal nutrition, establishment of the gut microbiome, maternal behavior, weaning, nutrition during growth, growth rate, socialization with conspecifics and humans, rehoming and neutering. Despite evidence in some species that the disorders reviewed here reflect the developmental origins of health and disease (DOHaD), developmental programming has rarely been studied in dogs and cats. Priorities and strategies to increase knowledge of early-life risk factors and DOHaD in dogs and cats are discussed. Critical windows of development are proposed: preconception, gestation, the suckling period, early growth pre-neutering or pre-puberty, and growth post-neutering or post-puberty to adult size, the durations of which depend upon species and breed. Challenges to DOHaD research in these species include a large number of breeds with wide genetic and phenotypic variability, and the existence of many mixed-breed individuals. Moreover, difficulties in conducting prospective lifelong cohort studies are exacerbated by discontinuity in pet husbandry between breeders and subsequent owners, and by the dispersed nature of pet ownership.

Companion Cats Show No Effect of Trial-and-Error Learning Compared to Dogs in a Transparent-Obstacle Detour Task

We tested companion cats and dogs in similar indoor conditions using identical procedures in the classic detour task around a V-shaped transparent wire-mesh fence. Besides the control group, we used two types of laser light-pointing demonstration (moving around the fence, or pointing straight at the reward). We found that dogs reached the food reward faster than cats; across consecutive trials, only the dogs showed improvement in their speed and dogs continued to use the same side for detouring after a preceding successful attempt, while cats chose the side for detouring irrespective of their previous successful trials. In addition, 'demonstrating' a detour with the laser did not influence the speed or direction of the detour of the subjects; and dogs looked back to their owner more frequently than the cats did. We discuss the possibility that for dogs, detouring along a transparent obstacle represents a more problematic task than for cats; therefore, dogs strongly rely on their previous experiences. This is the first time that cats were successfully tested in this detour paradigm in direct comparison with dogs. The results are relevant from the aspect of testing cognitive performance in companion cats, which are known to be notoriously reluctant to engage with novel experimental situations.

Effect of Sex and Reproductive Status on Inhibitory Control and Social Cognition in the Domestic Dog (Canis familiaris)

Simple Summary

Various behavioral differences exist between male and female dogs, but very little research has focused on how sex influences cognition. Even fewer studies have taken sex hormones into account. Our aim was to investigate whether dogs’ sex and neutering status can influence two important cognitive traits: inhibitory control and social cognition. Inhibitory control was assessed using the cylinder test. In this task, the dog is required to inhibit reaching for a treat directly through a transparent barrier, and instead go around the barrier to access the treat. Social cognition was assessed using the unsolvable task, during which a food reward is visible but impossible to access. Dogs have three opportunities for action in this situation: (a) persisting with the problem independently, (b) seeking attention from a human, or (c) abandoning the task. Males were more impulsive and independent compared to females, whereas females had greater inhibitory control and were more likely to gaze at a human during a problem-solving situation. Since neutering status did not affect the results, it seems likely that these sex differences arose during early development and were not affected by levels of circulating sex hormones to a great extent.

Abstract

Sex differences in a variety of cognitive traits have long been reported in various species, including dogs. However, only a few canine studies have taken the possible effect of reproductive hormones into account. The aim of this study was to investigate the effects of sex and reproductive status of pet dogs (N = 1032) on two cognitive traits: inhibitory control and social cognition. Inhibitory control was assessed using the cylinder test, and the dogs’ tendency to initiate social contact with a human during a problem-solving situation was assessed using the unsolvable task. Female dogs had a significantly higher success rate in the cylinder test compared to males, and they spent significantly more time in human-directed behavior during the unsolvable task. In contrast, males spent significantly more time in independent behavior during the unsolvable task. Reproductive status had no significant effect on the results of the cylinder test or the unsolvable task. Our results showed that female dogs asked for more help/used a more cooperative strategy during a problem-solving situation and had greater inhibitory control compared to males. According to our results, it seems likely that these sex differences were not influenced to a large extent by reproductive hormones.

Enhancing the Selection and Performance of Working Dogs

Dogs perform a variety of integral roles in our society, engaging in work ranging from assistance (e.g., service dogs, guide dogs) and therapy to detection (e.g., search-and-rescue dogs, explosive detection dogs) and protection (e.g., military and law enforcement dogs). However, success in these roles, which requires dogs to meet challenging behavioral criteria and to undergo extensive training, is far from guaranteed. Therefore, enhancing the selection process is critical for the effectiveness and efficiency of working dog programs and has the potential to optimize how resources are invested in these programs, increase the number of available working dogs, and improve working dog welfare. In this paper, we review two main approaches for achieving this goal: (1) developing selection tests and criteria that can efficiently and effectively identify ideal candidates from the overall pool of candidate dogs, and (2) developing approaches to enhance performance, both at the individual and population level, via improvements in rearing, training, and breeding. We summarize key findings from the empirical literature regarding best practices for assessing, selecting, and improving working dogs, and conclude with future steps and recommendations for working dog organizations, breeders, trainers, and researchers.

Dissociating the effects of delay and interference on dog (Canis familiaris) working memory

Delayed matching-to-sample (dMTS) is commonly used to study working memory (WM) processes in non-humans. Previous procedures for studying dog WM, including versions of the dMTS, did not separate the impact of delay and interference on memory performance. These studies were also limited to auditory and spatial stimuli, neglecting dogs' dominant sensory modality (i.e., olfaction). Therefore, we designed the first olfactory dMTS in dogs, with systematically varied delays and number of odors in a session, to dissociate the effects of delay and within-session proactive interference on dog WM. Dogs (n = 5) initially trained on matching-to-sample with 48 odors, with a zero-second delay, were tested on four delay lengths (0, 30, 60, and 90 s), counterbalanced across three, trial-unique, sessions. Although there was a slight decrease in accuracy across delays, dogs performed above chance on delays up to 60 s, suggesting a WM duration of at least 60 s. To explore the effect of within-session proactive interference on WM duration, the size of the stimulus set was reduced to six and two odors. There was no effect on the memory function with six odors compared to the trial-unique sessions. However, the interference caused by the two-odor set was enough to decrease accuracy at each delay length. These findings suggest that forgetting in dog working memory for odors can be simultaneously influenced by delay and within-session proactive interference.

Validation of a Behavior Test for Predicting Puppies' Suitability as Detection Dogs

Behavioral characteristics are the most influential factor in the success of a working dog. The need for highly capable detection dogs continues to rise; but reliable methods for early selection are lacking. The current study aimed to assess the reliability and validity of a behavioral test for assessing detection dog suitability. A cohort of candidate detection dog puppies (n = 60) were tested at 3; 5; and 11 months of age; as well as at the completion of training at approximately one year. Tests were designed to assess important detection dog behavioral characteristics such as search ability and fearfulness. Inter-rater reliability was high between independent observers. Convergent validity was demonstrated by comparing Principal Component Analysis (PCA) scores from the behavior test to trainer ratings using the Canine Behavioral Assessment and Research Questionnaire (C-BARQ) and a survey of detection dog traits. Performance on the behavior test predicted adult selection as a detection dog as early as 3 months. The methods reported will be valuable for improving selection measures and enhancing collaborations across breeding programs in order to increase the availability of highly capable detection dogs.

Is cognition the secret to working dog success?

Dogs' special relationship with humans not only makes them ubiquitous in our lives, but working dogs specifically perform essential functions for us such as sniffing out bombs and pulling wheelchairs for the disabled. To enhance the performance of working dogs, it is essential to understand the cognitive skills that underlie and lead to their success. This review details recent work in the field of canine cognition, including how dogs have evolved socio-cognitive skills that mimic or, in some cases, rival even our closest primate relatives. We review how these findings have laid the foundation for new studies that hope to help enhance working dog programs. This includes work that has begun to reveal the development and stability of the most important traits for service work. Discoveries like these suggest the possibility of translating what we have learned to improve breeding, selection, and training for these jobs. The latest research we review here shows promise in contributing to the production of better dogs and, consequently, more help for people.

Dog cognitive development: a longitudinal study across the first 2 years of life

While our understanding of adult dog cognition has grown considerably over the past 20 years, relatively little is known about the ontogeny of dog cognition. To assess the development and longitudinal stability of cognitive traits in dogs, we administered a battery of tasks to 160 candidate assistance dogs at 2 timepoints. The tasks were designed to measure diverse aspects of cognition, ranging from executive function (e.g., inhibitory control, reversal learning, memory) to sensory discrimination (e.g., vision, audition, olfaction) to social interaction with humans. Subjects first participated as 8-10-week-old puppies, and then were retested on the same tasks at ~ 21 months of age. With few exceptions, task performance improved with age, with the largest effects observed for measures of executive function and social gaze. Results also indicated that individual differences were both early emerging and enduring; for example, social attention to humans, use of human communicative signals, independent persistence at a problem, odor discrimination, and inhibitory control all exhibited moderate levels of rank-order stability between the two timepoints. Using multiple regression, we found that young adult performance on many cognitive tasks could be predicted from a set of cognitive measures collected in early development. Our findings contribute to knowledge about changes in dog cognition across early development as well as the origins and developmental stability of individual differences.

Selecting Dogs for Explosives Detection: Behavioral Characteristics

Detection dogs are widely considered the most effective and adaptive method for explosives detection. Increases in emerging sophisticated threats are accelerating the demand for highly capable explosives detection, causing a strain on available supplies of quality canines worldwide. These strains are further compounded by rigorous behavioral standards required to meet mission-specific capabilities, leading to high rates of dogs disqualified from training or deployment. Ample research has explored the behavioral characteristics important for assistance, guide, and other traditional working roles, while those corresponding to more specialized tasks such as detection of explosives are not as well-understood. In this review we aim to identify the behavioral characteristics important for operational tasks of explosives detection dogs, contrasting with that of other working roles and highlighting key differences between explosives and other types of detection dogs. Further, we review the available research on methods for assessing and selecting candidate detection dogs and make recommendations for future directions and applications to the industry. Improvements and standardization in assessment technology allowing for the identification and enhancement of behavioral characteristics will be key to advancing canine detection technology in general.