Personality traits affecting judgement bias task performance in dogs (Canis familiaris).

Certain personality traits (e.g. anxiousness, fearfulness), are known to affect the cognitive processing of environmental stimuli, such as the judgement of ambiguous stimuli (judgement bias). Our aim was to assess if personality traits are predictive of a more or less 'pessimistic' or 'optimistic' judgement bias in the domestic dog. We assessed dog personality (N = 31) using two validated protocols: the Dog Mentality Assessment (standardised battery test) and the CBARQ (owner-based survey). We used a common task based on the animals' latency to approach a bowl placed in one of three ambiguous positions (Near Positive, Middle, Near Negative) between a baited (Positive) and a non-baited food bowl (Negative) to assess judgement bias. Linear Mixed Model analyses revealed that dogs scoring higher on sociability, excitability and non-social-fear had shorter response latencies to bowls in an ambiguous location, indicating a more 'optimistic' bias. In contrast, dogs scoring higher on separation-related-behaviour and dog-directed-fear/aggression traits were more likely to judge an ambiguous stimulus as leading to a negative outcome, indicating a more 'pessimistic' bias. Results, partially consistent with previous findings in humans, indicate that personality plays a role in the cognitive processing of environmental stimuli in the domestic dog.

Stability of motor bias in the domestic dog, Canis familiaris.

This study explored the relationship between four measures of canine paw preference to establish whether the distribution, direction or strength of motor bias was consistent between tasks. Thirty-two dogs had their paw preferences tested using the Kong ball, tape, lift paw and First-stepping tests. A smaller sample were re-tested 6 months later. The distribution of the dogs' paw preferences was not significantly different from that expected by chance for the Kong ball and lift paw tests; dogs were significantly more inclined towards ambilaterality on the tape and First-stepping tests. More female dogs employed their right paw on the lift paw test; males were more likely to be ambilateral or left-pawed. There was no significant correlation in the direction of dogs' paw use for any tests. The First-stepping and lift paw tests were positively correlated for strength of paw use. Analysis revealed a significant correlation in direction and strength of dogs' paw use between the first and second attempts of all measures, except the tape test. Findings suggest that paw preference in the dog is not consistent between tasks, although stable over time. The study raises questions as to which test of paw preference is the most appropriate to employ.

Cognitive bias and paw preference in the domestic dog (Canis familiaris).

Limb use, an indicator of hemispheric functioning, may be a useful predictor of cognitive bias and hence vulnerability to welfare risk. The relationship between cognitive bias and motor asymmetry, however, has been subject to little investigation. This study explored the association between motor asymmetry and cognitive bias in the domestic dog, a species that displays lateral bias in the form of paw preferences and exhibits positive and negative affective states. Thirty pet dogs had their paw preferences assessed using the Kong ball test. The subjects' affective state was assessed using a cognitive bias test in which the animals' latency to approach a bowl placed in 1 of 3 ambiguous positions was recorded. Animals veering more toward a left-paw preference were found to be significantly slower to approach the bowl placed in 1 of the ambiguous positions than ambilateral or right-pawed dogs. Left-pawed subjects approached the bowl located at the 3 ambiguous positions at roughly the same speed, while ambilateral and right-pawed animals became increasingly slower to approach the bowl the further it was located from the baited food bowl. The study points to a possible relationship between cognitive bias and paw preference in the dog, with left-pawed animals being more negative or "pessimistic" in their cognitive outlook than right-pawed or ambilateral individuals. It is proposed that limb preference testing might offer a more practical and straightforward way of identifying individuals at risk from poor welfare by virtue of how they perceive the world than more time-consuming cognitive bias tests. (PsycINFO Database Record

Association between lateral bias and personality traits in the domestic dog (Canis familiaris).

Behavioral laterality reflects the cerebral functional asymmetry. Measures of laterality have been associated with emotional stress, problem-solving, and personality in some vertebrate species. Thus far, the association between laterality and personality in the domestic dog has been largely overlooked. In this study, we investigated whether lateralized (left or right) and ambilateral dogs differed in their behavioral response to a standardized personality test. The dog's preferred paw to hold a Kong ball filled with food and the first paw used to step-off from a standing position were scored as laterality measures. The Dog Mentality Assessment (DMA) test was used to assess 5 personality traits (e.g., sociability, aggressiveness) and a broader shy-boldness dimension. No differences emerged between left- and right-biased dogs on any personality trait. Instead, ambilateral dogs, scored using the Kong test, scored higher on their playfulness (Z = -1.98, p = .048) and Aggressiveness (Z = -2.10, p = .036) trait scores than did lateralized (irrespective of side) dogs. Also, ambilateral dogs assessed by using the First-Stepping test scored higher than lateralized dogs on the Sociability (Z = -2.83, p = .005) and Shy-Boldness (Z = -2.34, p = .019) trait scores. Overall, we found evidence of a link between canine personality and behavioral laterality, and this was especially true for those traits relating to stronger emotional reactivity, such as aggressiveness, fearfulness, and sociability. (PsycINFO Database Record

Lateral bias and temperament in the domestic cat (Felis silvestris).

Research points to a relationship between lateralization and emotional functioning in humans and many species of animal. The present study explored the association between paw preferences and emotional functioning, specifically temperament, in a species thus far overlooked in this area, the domestic cat. Thirty left-pawed, 30 right-pawed, and 30 ambilateral pet cats were recruited following an assessment of their paw preferences using a food-reaching challenge. The animals' temperament was subsequently assessed using the Feline Temperament Profile (FTP). Cats' owners also completed a purpose-designed cat temperament (CAT) scale. Analysis revealed a significant relationship between lateral bias and FTP and CAT scale scores. Ambilateral cats had lower positive (FTP+) scores, and were perceived as less affectionate, obedient, friendly, and more aggressive, than left or right-pawed animals. Left and right pawed cats differed significantly on 1 trait on the CAT scale, namely playfulness. The strength of the cats' paw preferences was related to the animals' FTP and CAT scores. Cats with a greater strength of paw preference had higher FTP+ scores than those with a weaker strength of paw preference. Animals with stronger paw preferences were perceived as more confident, affectionate, active, and friendly than those with weaker paw preferences. Results suggest that motor laterality in the cat is strongly related to temperament and that the presence or absence of lateralization has greater implications for the expression of emotion in this species than the direction of the lateralized bias. (PsycINFO Database Record

The developmental origins of laterality: fetal handedness.

This paper reviews the evidence for lateralized motor behavior in the fetus around a number of key questions: does the fetus exhibit signs of laterality? when does lateralized motor behavior begin? is the lateralized preference consistently displayed? does prenatal handedness relate to postnatal handedness? and, does prenatal handedness relate to brain functioning? The evidence indicates that the fetus exhibits lateralized behavior from 10 weeks gestation, as soon as it independently moves its arms, and this is the precursor of lateralized motor behavior observed post-natally. Data is presented suggesting that the strength of laterality decreases with advancing gestation and this correlates with more efficient information processing as assessed by habituation. However extreme caution is warranted in attempting to link asymmetric motor behavior and brain function prenatally. The paper concludes that the initial developmental emergence of lateralized behavior is under genetic control and is a fundamental feature of prenatal human development.

Long-term flavor recognition in humans with prenatal garlic experience.

The human fetus learns about its chemosensory environment and this influences its behavior at birth and during the nursing period. This study examined whether prenatal experience could influence behavior much later in life. The dietary preference of two groups of children (8- to 9-years old) was examined. Mothers of one group had consumed garlic during pregnancy, mothers of the control group had not. Children received two tests, 1 month apart, of a meal containing two portions of potato gratin, one flavored with garlic. The total amount of potato, and the percentage of garlic flavored potato, eaten was calculated and examined separately by ANOVA for factors of prenatal exposure, the child's sex, and trial. Children prenatally exposed to garlic ate significantly more garlic flavored potato and a significantly greater overall amount of potato on trial 2, compared to controls. The results demonstrate prenatal experience may affect behavior well into childhood.

Fetal brain function in response to maternal alcohol consumption: early evidence of damage.

BACKGROUND: Studies of the adverse neurobehavioral effects of maternal alcohol consumption on the fetus have been largely confined to the postnatal period, after exposure to alcohol has finished. This study explored the brain function of the fetus, at the time of exposure to alcohol, to examine its effect on information processing and stability of performance. METHODS: Five groups of fetuses, defined by maternal alcohol consumption patterns, were examined: control (no alcohol); moderate (5 to 10 units/wk either drunk evenly across the week or as a binge, in 2 to 3 days); heavy (20+ units/wk drunk evenly or as a binge). Fetal habituation performance was examined on 3 occasions, separated by 7 days, beginning at 35 weeks of gestation. The number of trials required to habituate on each test session and the difference in performance across test sessions were recorded. RESULTS: Fetuses exposed to heavy binge drinking required significantly more trials to habituate and exhibited a greater variability in performance across all test sessions than the other groups. Maternal drinking, either heavily but evenly or moderately as a binge, resulted in poorer habituation, and moderate binge drinking resulted in greater variability compared with no, or even, drinking. CONCLUSIONS: Decreased information processing, reflected by poorer habituation, and increased variability in performance may reflect the initial manifestations of structural damage caused by alcohol to the brain. These results will lead to a greater understanding of the effects of alcohol on the fetus's brain, enable the antenatal identification of fetal alcohol spectrum disorders, and lead to the early implementation of better management strategies.

Alcohol delays the emergence of the fetal elicited startle response, but only transiently.

Prenatal exposure to alcohol may exert a significant detrimental effect on the functioning of the individual's brain, however few studies have examined this before birth. This longitudinal study examined the effect of maternal alcohol consumption on the elicited startle response of the fetus. Two groups of fetuses were examined: one whose mothers drank alcohol (approximately 10 units per week); the other whose mothers did not drink alcohol. Fetuses were examined at 29, 32 and 35 weeks gestation and their startle response observed using ultrasound in response to 2 presentations of a pink noise (70-250Hz) at 90dB(A) separated by 30s. Fetuses exposed to alcohol exhibited a weaker startle response at 29 weeks gestation than did fetuses not exposed to alcohol. There was no difference in the response at 32 and 35 weeks gestation. To ensure that the effects were not due to a more general effect of alcohol on fetal movement, a second experiment compared the spontaneous movements (observed on ultrasound for 45 min) of fetuses whose mothers drank alcohol and fetuses of mothers who didn't drink alcohol. There were no differences in movements exhibited by the fetuses. The results suggest that exposure to alcohol delays the emergence of the elicited startle response at 29 weeks gestation but this delay has disappeared by 32 weeks gestation. The possible role of altered neural development, acute exposure to alcohol and disruptions to the fetus's behavioural repertoire, in mediating these effects are discussed.

Sex differences in fetal habituation.

There is some evidence for sex differences in habituation in the human fetus, but it is unknown whether this is due to differences in central processing (habituation) or in more peripheral processes, sensory or motor, involved in the response. This study examined whether the sex of the fetus influenced auditory habituation at 33 weeks of gestation, and whether this was due to differences in habituation or in the sensory or motor components using a set of four experiments. The first experiment found that female fetuses required significantly fewer stimulus presentations to habituate than males. The second experiment revealed no difference in the spontaneous motor behaviour of male and female fetuses. The third experiment examined auditory intensity thresholds for the stimuli used to habituate the fetus. No differences in thresholds were found between males and females, although there was inter-individual variability in thresholds. A final experiment, using stimuli individualized for that particular fetus' auditory intensity threshold, found that female fetuses habituated faster than males. In combination, the studies reveal that habituation in the human fetus is affected by sex and this is due to a difference in central 'information processing' of the stimuli rather than peripheral aspects of the response. It is argued that male and female fetuses present different neurobehavioural developmental trajectories, with females more advanced at 33 weeks than males. This study suggests that research examining prenatal behaviour should consider the factor of fetal sex. This may be particularly pertinent where there is an intention to use the results diagnostically.

Olfactory discrimination in the western lowland gorilla, Gorilla gorilla gorilla.

The olfactory abilities of great apes have been subject to little empirical investigation, save for a few observational reports. This study, using an habituation/dishabituation task, provides experimental evidence for a core olfactory ability, namely, olfactory discrimination, in the gorilla. In Experiment 1, six zoo-housed western lowland gorillas were individually presented with the same odour on four trials, and with a novel odour on the fifth trial. Odours (almond and vanilla) were presented on plastic balls, and behavioural responses of sniffing and chewing/licking the balls were recorded. A second experiment presented the same odour on four trials and no odour on the fifth to examine whether any dishabituation was due to the presence of a new odour or the absence of the familiar odour. Gorillas habituated their behaviour with repeated presentation of the same odour, but dishabituated, i.e. increased sniffing and chewing/licking, when presented with the novel odour. No dishabituation was noted when using water as the stimulus across all trials or when used as the novel odour. Overall, results show that gorillas are able to discriminate between odours.

Fetal habituation in assisted conception.

BACKGROUND: Neurodevelopment outcomes of children conceived by Assisted Reproductive Technology (ART)have been the subject of much recent attention. To date there are no reports of neurodevelopmental performance before birth in this group. AIMS: To compare habituation (a measure of brain function) in fetuses conceived by assisted reproduction techniques (ART) with naturally conceived (NC) fetuses. STUDY DESIGN: Case control study. SUBJECTS: Women with singleton pregnancies matched for maternal age, parity and smoking were recruited in 2 groups: ART (n=20) and NC (n=20). OUTCOME MEASURES: Sound stimuli (250 Hz, 110 dB) at 10 second intervals lasting 2 s were administered to the fetus. The end point was habituation (cessation of movement for five consecutive stimuli) or a maximum of 30 stimuli. Responses of the fetus were observed with ultrasound at 28, 32 and 36 weeks' gestation, video-recorded and anonymised for analysis. RESULTS: At 28 weeks' gestation significantly more ART fetuses responded to sound of 250 Hz, 110 dB (p=0.02) but this difference did not persist at 32 and 36 weeks'. There was a significant increase in nonresponders as gestation advanced in the ART group. There was no difference in habituation or mean number of trials to habituate at all three gestations. CONCLUSIONS: ART fetuses demonstrated no differences in habituation suggesting that there is no neurodevelopment delay. However, a decrease in response to sound as gestation advances might be a harbinger for poor perinatal outcomes and needs exploration.

Individually identifiable body odors are produced by the gorilla and discriminated by humans.

Many species produce odor cues that enable them to be identified individually, as well as providing other socially relevant information. Study of the role of odor cues in the social behavior of great apes is noticeable by its absence. Olfaction has been viewed as having little role in guiding behavior in these species. This study examined whether Western lowland gorillas produce an individually identifiable odor. Odor samples were obtained by placing cloths in the gorilla's den. A delayed matching to sample task was used with human participants (n = 100) to see if they were able to correctly match a target odor sample to a choice of either: 2 odors (the target sample and another, Experiment 1) and 6 odors (the target sample and 5 others, Experiment 2). Participants were correctly able to identify the target odor when given either 2 or 6 matches. Subjects made fewest errors when matching the odor of the silverback, whereas matching the odors of the young gorillas produced most errors. The results indicate that gorillas do produce individually identifiable body odors and introduce the possibility that odor cues may play a role in gorilla social behavior.

Lateralised swimming behaviour in the California sea lion.

Lateralised motor behaviour in the pinnipeds has been subject to little investigation. This study examined the swimming behaviour of seven zoo-housed California sea lions to determine whether they exhibited a directional bias in their motor behaviour. Data were collected on the direction of the animals' swimming patterns from the point of entering a pool of water from dry land. Each animal was studied for 100 episodes of swimming. All seven of the sea lions showed significant (P<0.001) bias in the direction of their swimming, although unidirectional bias was not observed at the level of the population. The direction of the sea lions' swimming patterns varied significantly according to the animals' sex. Males showed a preference at the level of the population for swimming in a clockwise direction, while females showed a population-level counterclockwise swimming preference. Overall, the findings appear to suggest that California sea lions, like other marine mammals, exhibit motor bias in the direction of their swimming patterns, although further work using larger sample sizes is needed before more firm conclusions regarding motor laterality in this species can be reached.

Perinatal olfactory learning in the domestic dog.

The ability of individuals to learn about chemosensory stimuli in the prenatal, or immediate postnatal, period may be advantageous in acquiring information about "safe" foods after weaning. In this study, we examined the influence of perinatal exposure to aniseed via the mother's diet on a two-choice food test in the domestic dog. Pups were tested at 10 weeks of age following "prenatal" exposure to aniseed (the last 20 days of gestation), "postnatal" exposure to aniseed (the first 20 days after birth), "perinatal" exposure to aniseed (pre- and postnatal exposure combined), or no exposure to aniseed prenatally or postnatally (control). Perinatal exposure resulted in a significantly greater preference for the aniseed food than the other types of exposure. At 10 weeks, there was no evidence for the retention of any prenatal learning of the aniseed. It is suggested that exposure to a chemosensory stimulus across the perinatal period results in a greater effect than simply the sum of pre- and postnatal exposure due to priming of the chemosensory system via prenatal chemosensory experience. Such a system may confer survival advantages by promoting the acquisition of information about safe foods.

How many footsteps do dogs need to determine the direction of an odour trail?

Dogs have the ability to determine the direction of an odour trail left by a human. This study examined how much olfactory information from this trail is required by dogs to determine direction. Six dogs, able to determine direction, were tested on a 21 footstep trail laid on 21 individual carpet squares, one footstep per square, by the same individual wearing the same shoes. Dogs brought in at right-angles to the trail at its centre were able to correctly determine direction better than chance (P < 0.025). Dogs were unable to determine direction when the order of the footsteps was randomized by rearranging the order of the carpet squares. When the individual odour cue was removed, but ground disturbance left, dogs were unable to determine direction, indicating that it was the odour of the individual that was used to determine direction. In the final experiment the number of footsteps made available to the dog was reduced from 21 to 11 and then 9, 7, 5 and finally 3. Dogs were able to determine direction from 5 footsteps but not 3. It was calculated that it takes approximately 1-2 s for the odour information in footsteps to change to provide discernible information that can be used by dogs to determine direction. The process by which dogs may determine direction from odour cues is discussed.

Prenatal thumb sucking is related to postnatal handedness.

This study followed-up 75 individuals who were observed sucking their thumb as fetuses and examined their handedness, assessed by a modified version of the Edinburgh Handedness Inventory, at 10-12 years of age. Of 60 right-handed fetuses, all were right-handed postnatally; 10 of 15 left-handed fetuses were left-handed and five right-handed. Male left thumb sucking fetuses were more likely to be right-handed children than females. The study indicates that the prenatal exhibition of lateralised motor behaviour, in this case thumb sucking, is indeed related to postnatal handedness, perhaps more strongly for right 'handed' fetuses than left 'handed' fetuses.

Maternal alcohol consumption during pregnancy may delay the development of spontaneous fetal startle behaviour.

Maternal alcohol consumption during pregnancy may delay the development of spontaneous fetal startle behaviour. Previous study indicated that fetuses exposed to alcohol exhibited a significantly higher incidence of spontaneous startles compared to fetuses not exposed at 20 weeks gestation. This study examined startle behaviour longitudinally from 20 to 35 weeks gestation to determine whether the previous results were due to 'developmental delay' or a 'permanent effect'. The number of spontaneous startles exhibited by fetuses of mothers who drank during pregnancy and fetuses whose mothers did not drink was recorded at 20, 25, 30 and 35 weeks gestation during a 45-min observation. The results indicate that exposure to alcohol during pregnancy significantly increases the exhibition of spontaneous startles by the fetus but across gestation there is significant catch-up in startle behaviour. The results suggest exposure to alcohol delays the natural maturation of spontaneous startle behaviour of the fetus but also has a smaller 'permanent' effect. It is suggested that these effects are mediated by alcohol exerting an effect on the inhibitory pathways controlling startle behaviour.

Maternal alcohol consumption during pregnancy and fetal startle behaviour.

The startle behaviour of the fetus (both spontaneous and elicited) was examined in fetuses of mothers who drank alcohol and mothers who did not. Fetuses exposed to alcohol showed a higher frequency of spontaneous startles and were less likely to exhibit a normal startle in response to a vibroacoustic stimulus. These differences illustrate a teratogenic effect of alcohol on CNS functioning in utero, possibly associated with brainstem damage.