Dog paw preference shows lability and sex differences

Paw preferences in domestic dogs were studied using three different behavioural tests, recording frequency, duration and latency of paw use. No overall population tendency to right- or left-paw preference was seen on any of the tests, nor could a sub-population of handed dogs be detected. This failure to replicate previous reports that male dogs tend to use their left paws while females use their right was counterbalanced by a significant tendency for male dogs to use their left paw when initially presented with one test, and for the latency of left paw use to be significantly shorter than that for right paw use on these initial presentations. This significant effect disappeared with repeated presentation of the test, and was not present in females. We conclude that behavioural lateralisation appears to be a labile category in dogs, and may be related to brain hemispheric effects in responding to novel stimuli.     

Paw preferences in cats (Felis silvestris catus) living in a household environment

Unrestrained, naı̈ve cats (Felis silvestris catus) (n=48: 28 males and 20 females), living in a natural domestic environment, were studied for paw preferences using a food reaching test. A total of 46% were right-preferent, 44% were left-preferent and 10% were ambilateral. 60% of the cats in our sample used one paw 100% of the time. This preference was stable over time (10 weeks), and was not influenced by the presence of food residue on the cats' non-preferred paw. There was no difference between male and female cats in the proportions of left and right paw-preferent individuals. We have reviewed the literature reporting paw preferences in cats and conclude that in static food-reaching tests, domestic cats show a marked paw preference with an equal distribution of left- and right-preferent individuals. They do not, however, show a group or population bias toward the use of any one paw. There are no significant sex differences. In contrast, there is previously published evidence which appears to suggest that moving-target reaching tests uncover a left-sided behavioural asymmetry.     

Man's Underground Best Friend: Domestic Ferrets, Unlike the Wild Forms, Show Evidence of Dog-Like Social-Cognitive Skills

Recent research has shown that dogs' possess surprisingly sophisticated human-like social communication skills compared to wolves or chimpanzees. The effects of domestication on the emergence of socio-cognitive skills, however, are still highly debated. One way to investigate this is to compare socialized individuals from closely related domestic and wild species. In the present study we tested domestic ferrets (Mustela furo) and compared their performance to a group of wild Mustela hybrids and to domestic dogs (Canis familiaris). We found that, in contrast to wild Mustela hybrids, both domestic ferrets and dogs tolerated eye-contact for a longer time when facing their owners versus the experimenter and they showed a preference in a two-way choice task towards their owners. Furthermore, domestic ferrets, unlike the wild hybrids, were able to follow human directional gestures (sustained touching; momentary pointing) and could reach the success rate of dogs. Our study provides the first evidence that domestic ferrets, in a certain sense, are more dog-like than their wild counterparts. These findings support the hypothesis that domestic species may share basic socio-cognitive skills that enable them to engage in effectively orchestrated social interactions with humans.     

Do Dogs (Canis lupus familiaris) Make Counterproductive Choices Because They Are Sensitive to Human Ostensive Cues?

Dogs appear to be sensitive to human ostensive communicative cues in a variety of situations, however there is still a measure of controversy as to the way in which these cues influence human-dog interactions. There is evidence for instance that dogs can be led into making evaluation errors in a quantity discrimination task, for example losing their preference for a larger food quantity if a human shows a preference for a smaller one, yet there is, so far, no explanation for this phenomenon. Using a modified version of this task, in the current study we investigated whether non-social, social or communicative cues (alone or in combination) cause dogs to go against their preference for the larger food quantity. Results show that dogs' evaluation errors are indeed caused by a social bias, but, somewhat contrary to previous studies, they highlight the potent effect of stimulus enhancement (handling the target) in influencing the dogs' response. A mild influence on the dog's behaviour was found only when different ostensive cues (and no handling of the target) were used in combination, suggesting their cumulative effect. The discussion addresses possible motives for discrepancies with previous studies suggesting that both the intentionality and the directionality of the action may be important in causing dogs' social biases.     

A study of correlates of hand preferences in squirrel monkeys (Saimiri sciureus)

The purpose of this study was to test the influence of sex, age, social rank, matriline membership, posture, and visual and tactual motor control on manual preferences inSaimiri sciureus. A well-established social group of 12 squirrel monkeys, aged 2 to 14 yrs and consisting of two matrilines with social rank known for each animal, was presented with four different food-reaching tasks and assessed for hand preferences with a minimum of 100 reaches per animal. Frequency of occurrence of hand preferences at the group level and degree of hand preferences at the individual level depended on posture and on whether the reaching act took place under visual or tactual guidance. Sex, age, social rank, and matriline membership were not found to determine frequency of occurrence, direction or degree of hand preferences with the exception of one task in which a significant negative correlation between the degree of hand preference and age was found. Nine out of 12 monkeys showed task-dependent changes in the hand they used preferentially while only three animals preferred the same hand in all four tasks. Significant preferences for the use of right or left hand on a given task were distributed almost equally between individuals. Thus, the results of this study suggest task-specific demands like posture and/or whether reaching was visually or tactually guided to be the major correlates of hand preferences in food-reaching tasks in squirrel monkeys.     

Behavioural changes and aversive conditioning in hunting dogs by the second-year confrontation with domestic sheep

Domesticated dogs occasionally exhibit predatory behaviour towards domestic sheep when running loose in pasture. Both young and old dogs of either sex may chase sheep. Electronic dog collars applying electric shocks are utilised as one method of training dogs to refrain from attacking sheep. This device is used for a number of other training purposes which have raised concern for the welfare of the dogs being trained. This study aims at testing long-term learning effects of previous sheep tests on sheep chasing in hunting dog breeds (Norwegian elkhounds (grey), English setters, and hare hunting dogs), in particular with use of electronic dog collars, in addition to uncovering potential secondary negative effects on dogs' behaviour and mental stability. The dogs (N=114) were subjected to three tests for two subsequent years, the second year being reported here. Dogs were tested for reactions to different stimuli, including a sheep, in a path test. In a sheep confrontation test, dogs were fenced in with a sheep group and given el. shocks when approaching 1-2m from sheep. A questionnaire to the dog owners reported differences in dogs' behaviour between the years.Dogs showed weaker or delayed behavioural responses in both tests in the second year. No dogs showed interest in or attacked a lone sheep in the path test in the second year, while almost two thirds of them did so the first year. In the sheep confrontation test, the dogs exhibited comparatively hesitant initial hunting motivation the second year, being more evident in dogs which received el. shocks the first year. No dogs chased or attacked sheep as their first response in this test, while half of them did so the first year. The proportion of dogs attacking sheep during the entire test was reduced to almost one fourth. The number of el. shocks administered reduced by the second year, and only one of the dogs that received el. shocks the first year received el. shocks the second year. The owners reported no negative effect on the dogs' behaviour during the year ensuing el. shock treatment. Eighteen of the 24 dogs reported by owners to exhibit behavioural changes lost their previous interest in sheep.The second-year tests indicate that aversive conditioning with the use of electronic dog collar may be an efficient method for reducing the probability of a dog chasing or attacking grazing sheep. No adverse effects were observed with our test procedure.     

Consistency of hand preference across low-level and high-level tasks in capuchin monkeys (Cebus apella)

Numerous studies investigating behavioral lateralization in capuchins have been published. Although some research groups have reported a population-level hand preference, other researchers have argued that capuchins do not show hand preference at the population level. As task complexity influences the expression of handedness in other primate species, the purpose of this study was to collect hand preference data across a variety of high- and low-level tasks to evaluate how task complexity influences the expression of hand preference in capuchins. We tested eleven captive brown capuchin monkeys (Cebus apella) to determine if they show consistent hand preferences across multiple high- and low-level tasks. Capuchins were expected to display high intertask consistency across the high-level tasks but not the low-level tasks. Although most individuals showed significant hand preferences for each task, only two of the high-level tasks that involved similar hand motions were significantly positively correlated, indicating consistency of hand preference across these tasks only. None of the tasks elicited a group-level hand preference. High-level tasks elicited a greater strength of hand preference than did low-level tasks. No sex differences were found for the direction or strength of hand preference for any task. These results contribute to the growing database of primate laterality and provide additional evidence that capuchins do not display group-level hand preferences.     

The relationship of callosal anatomy to paw preference in dogs

Previous studies have described the paw preference and asymmetry in dog brains, based on experimental studies. The purpose of the present study is to investigate a possible association between callosal anatomy and paw preference in dogs. The midsagittal area of the dog corpus callosum was measured in its entirety and in six subdivisions in a sample of 21 brains obtained from 9 male and 12 female mongrel dogs which had paw preference testing. The present study showed significant paw differences in dog corpus callosum. A posterior segment of the callosum, the isthmus, was significantly larger in the right pawedness than the left.     

Sexual differences in certain forms of motor asymmetry in rats

Using three tests, studies have been made on locomotor lateralization in Wistar rats. It was shown that rat prefer the left paw for obtaining food from a tube, this preference being more pronounced in females. Females are more asymmetric also in preference of a side turn in a labyrinth: they choose the right side. In males, the preference of the right and left turns, as well as the absence of locomotor asymmetry were almost equal. These data are rather similar to those obtained for human subjects. Studies on the direction of rotation of rats after apomorphine injections did not reveal any sex differences or populational preferences.     

Interspecies hormonal interactions between man and the domestic dog (Canis familiaris)

To date, hormonal influence in interspecies interaction has not been examined. In a study of a dog agility competition among human/dog teams, men's pre-competition basal testosterone (T) levels were positively related to changes in dogs' cortisol levels from pre- to post-competition, but only among losing teams. Furthermore, pre-competition basal T in men on losing teams predicted more than half of the variance in dogs' cortisol change. This relationship was mediated through men's punitive and affiliative behaviors towards their dogs immediately after competition. Men's T change was also a significant predictor of dogs' change in cortisol such that men who experienced greater decreases in T after a loss were associated with dogs that experienced greater increases in cortisol. In winning teams, men's pre-competition T and T changes were unrelated to dogs' cortisol changes. These results are discussed in light of T as a proxy for dominance motivation as well as T's relation to stress across the species boundary.     

Dogs respond appropriately to cues of humans' attentional focus

Dogs' ability to recognise cues of human visual attention was studied in different experiments. Study 1 was designed to test the dogs' responsiveness to their owner's tape-recorded verbal commands (Down!) while the Instructor (who was the owner of the dog) was facing either the dog or a human partner or none of them, or was visually separated from the dog. Results show that dogs were more ready to follow the command if the Instructor attended them during instruction compared to situations when the Instructor faced the human partner or was out of sight of the dog. Importantly, however, dogs showed intermediate performance when the Instructor was orienting into 'empty space' during the re-played verbal commands. This suggests that dogs are able to differentiate the focus of human attention. In Study 2 the same dogs were offered the possibility to beg for food from two unfamiliar humans whose visual attention (i.e. facing the dog or turning away) was systematically varied. The dogs' preference for choosing the attentive person shows that dogs are capable of using visual cues of attention to evaluate the human actors' responsiveness to solicit food-sharing. The dogs' ability to understand the communicatory nature of the situations is discussed in terms of their social cognitive skills and unique evolutionary history.     

Dogs acquire food preferences from interacting with recently fed conspecifics

Social transmission of food preferences has been documented in many species including humans, rodents, and birds. In the current experiment, 12 pairs of domestic dogs (Canis familiaris) were utilized. Within each pair, one dog (the demonstrator) was fed dry dog food flavored with either basil or thyme. The second dog (the observer) interacted with one demonstrator for 10 min before being given an equal amount of both flavored foods. Observers exhibited a significant preference for the flavored diet consumed by their demonstrators, indicating that dogs, like rats, prefer foods smelled on a conspecific's breath.     

Brief communication: Hand preference for bimanual and unimanual feeding in captive gorillas: extension in a second colony of apes

Right-hand dominance is widely considered to be a uniquely human trait. Whether nonhuman primates exhibit similar population-level hand preferences remains a topic of considerable debate. Despite extensive research focusing on laterality in nonhuman primates, our interpretation of these studies is limited due to methodological issues including the lack of a common measure of hand preference and the use of tasks that may not be reliable indicators of handedness. The use of consistent methods between studies is necessary to enable comparisons within and between species and allow for more general conclusions to be drawn from these results. The present study replicates methods used in recent research reporting population-level right-handedness in captive gorillas (Meguerditchian et al.,2010). Observational data were collected on hand preference for unimanual and bimanual feeding in 14 captive western lowland gorillas (Gorilla gorilla gorilla). Individual-level preferences were found, primarily for bimanual feeding; however, the data reveal no group-level directional bias (contra Meguerditchian et al.). Like the study by Meguerditchian et al. (2010), though, bimanual feeding revealed significantly stronger hand preferences than unimanual reaching, and age, sex, group membership, or rearing history had no effect on hand preference. Finally, variations in diet and corresponding grip type between studies suggest that hand preferences may vary across bimanual tasks depending on grip morphology. This study aims to contribute to our existing knowledge of primate laterality by increasing the number of individuals investigated using methods that allow for comparisons with similar research.     

A multi-task assessment of hand lateralization in capuchin monkeys (Cebus apella)

Eight tasks were presented to ten tufted capuchin monkeys and hand preferences were recorded for each subject on each task. The strength of hand preferences varied accross tasks. Although no significant population-level left- or right-hand bias emerged for any of the tasks, there was a tendency toward greater left-hand use in a task requiring the use of probing tools. The data also confirm that simple reaching is of limited value as a measure of hand preference. Hand preferences in capuchin monkeys appear to be determined by a number of individual, species, and environmental factors.     

Preferences for Analgesic Treatments Are Influenced by Probability of the Occurrence of Adverse Effects and the Time to Reach Maximal Therapeutic Effects

Research on shared medical decision-making suggested that both the potency of a treatment and the probability of it being successful influence individual treatment preferences. Patients also need to consider the negative attributes of treatments, such as the occurrence of adverse effects or a slow start to the therapeutic effects. It remains unclear how these attributes influence individual treatment preferences. We investigated how the analgesic effect, the adverse effect, and the time-course effect influenced the preference of analgesic treatments. Forty-five healthy volunteers participated in three hypothetical analgesic decision-making tasks. They were instructed to imagine that they were experiencing pain and choose between two hypothetical analgesic treatments: the more potent radical treatment and the less potent conservative treatment. The potency of a treatment was countered by the following attributes: the probability of working successfully, the probability of inducing an adverse effect, and the time required for the treatment to reach its maximal effect. We found that (a) when the overall probability that a treatment would induce an adverse effect decreased, the participants changed their preference from a conservative treatment to a radical treatment; (b) when the time-course for a treatment to reach its maximal effect was shortened, the participants changed their preference from a conservative treatment to a radical treatment, and (c) individual differences in prior clinical pain and the degree of imagined pain relief were associated with preferences. The findings showed that the adverse effects and the time course of treatments guide the analgesic treatment preferences, highlighting the importance of sharing information about negative attributes of treatments in pain management. The findings imply that patients may over-emphasize the occurrence of adverse effect or a slow time-course of treatment effect. In terms of shared medical decision-making, clinicians should clarify these negative attributes related to treatment to patients.     

Contextual factors that heighten interest in coalitional alliances with men possessing formidable facial structures

Individuals use facial width-to-height ratio (fWHR) to infer men's formidability. We hypothesized that fWHR assessments would form a basis for men's coalitional value, with high-fWHR men being valuable in roles requiring physical strength. Five studies (N = 1323) tested how perceptions of formidability influence coalitional decisions. In addition to replicating previous findings indicating a preference for high-fWHR men in tasks requiring strength (Study 1), the formidability inference most associated with this high-fWHR preference was perceived strength and not aggressiveness (Studies 2a, 2b). Two pre-registered studies showed that activating competitive motivations increased preferences for high-fWHR allies (Study 3), though this preference appeared driven by a tolerance for high-fWHR men rather than an interest (Study 4). Findings provide evidence for how inferences of fWHR shape interpersonal preferences based on social contexts.     

Hand Preferences for a Haptic Task in Chimpanzees (Pan troglodytes)

We tested the hand preferences of 20 chimpanzees (Pan troglodytes) for a haptic task requiring individuals to search for grapes in an opaque bucket filled with water. We compared these data to the hand preferences displayed by the same chimpanzees during reaching and bimanual feeding tasks. The chimpanzees displayed no significant hand preference for the reaching or bimanual feeding tasks, but exhibited a right-hand preference while performing the haptic task. In contrast, New and Old World monkeys display left-hand preferences for similar tasks. We discuss the relevance of these findings for the evolution of handedness in primates.     

Hand preference in a captive island group of chimpanzees (Pan troglodytes)

Morphological cerebral asymmetries in chimpanzee brains, similar to those found in humans, in whom they are associated with speech and handedness, suggest the possibility of functional lateralization in the chimpanzee. This possibility was investigated by examining hand preferences in an island group of five chimpanzees on a series of unimanual and bimanual tasks that are diagnostic of human hand and cerebral dominance. Each subject was tested in a double compartment cage on three unimanual nonsequential, three unimanual sequential, and three bimanual coordination tasks. One of the three unimanual sequential tasks was a bar-press task that is analogous to the commonly used human finger-tapping task. For the unimanual tasks, exclusive of the bar-press, the chimpanzees showed a highly individualistic pattern of hand preference that did not change as a function of task complexity. On the bar-press task, four of five subjects produced higher rates with one hand compared to the other; however, relative hand performance on this task was unrelated to hand preference on the other unimanual tasks. For the group of subjects, performance rates did not differ between the left and right hands; however, a practice effect was observed for the right hand in all subjects. The bimanual tasks also revealed a complex pattern of individual handedness, with no trends apparent for the group as a whole. Consistent with previous findings, the results from these tests on this group of five chimpanzees suggest that cerebral morphological asymmetries in the chimpanzee are not associated with motor dominance as reflected in handedness.     

Amphetamine increases intertrial but not conditional instrumental responding in the cortico-basomedial amygdalar dogs

The effect of partial cortico-basomedial amygdaloid lesions on dogs' social behavior was investigated. The lesions did not affect the conditional instrumental responding (CRs) reinforced by petting or the dogs' need for petting (US). The lesions increased the number of intertrial responses (ITRs) in all dogs. Subsequently the effect of low amphetamine doses (0.5 mg/l kg) administered intramuscularly to the amygdalar animals on the same behavioral parameters of the social behavior was examined. Amphetamine did not affect CRs but dramatically increased the ITRs and dogs' need for petting. These findings suggest that the cortico-basomedial amygdaloid region may be involved in the cortical inhibitory mechanisms that are indispensable for promoting behavioral acts according to their usefulness and the situational context.     

Hand preference in unimanual and bimanual tasks and postural effect on manual laterality in captive red-capped mangabeys (Cercocebus torquatus torquatus)

Hand preference in 11 captive red-capped mangabeys (Cercocebus torquatus torquatus) was examined under different conditions: a free situation during spontaneous food processing, three different postural conditions (brachiating, and bipedal and tripedal standing), and a situation involving bimanual processing. Generally, individual laterality was found regardless of the task and behavior involved. However, the number of monkeys with hand preferences and the strength of the preference increased with the complexity of the tasks. The monkeys exhibited a significantly higher and positive mean manual preference index (HI) when they were hanging than when they were quadrupedal or sitting. The strength of manual preference (ABS-HI) was in turn higher when the monkeys were hanging or bipedal than when they were quadrupedal. The strength of manual preference was higher for both the bimanual and experimental tasks than for unimanual tasks and spontaneous activities. Although our sample was too small to allow us to make any generalizations concerning lateral preferences in red-capped mangabeys, we propose some hypotheses about the influence of posture stability and task complexity.