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This study examined the relative importance of contest experience and size differences to behavioral decisions over the course of contests. Using a mangrove rivulus fish, Kryptolebias marmoratus, we showed that although contest experience and size differences jointly determined contest outcomes, they affected contestants' interactions at different stages of contests. Contest experience affected behavioral decisions at earlier stages of contests, including the tendency and latency to launch attacks, the tendency to escalate contests into mutual attacks and the outcome of non-escalated contests. Once contests were escalated into mutual attacks, the degree of size difference affected the fish's persistence in escalation and chance of winning, but contest experience did not. These results support the hypothesis that contest experience modifies individuals' estimation of their fighting ability rather than their actual strength. Furthermore, (1) in contests between two naïve contestants, more than 60 % of fish that were 2-3 mm smaller than their opponent escalated the contest to physical fights, even though their larger opponents eventually won 92 % of escalated fights and (2) fish with a losing experience were very likely to retreat in the face of an opponent 2-3 mm smaller than them without escalating. The result that a 2-3 mm size advantage could not offset the influence of a losing experience on the tendency to escalate suggests that, as well as depending on body size, the fish's physical strength is influenced by other factors which require further investigation.

Synopsis A suite of correlated behaviors reflecting between-individual consistency in behavior across multiple situations is termed a ‘‘behavioral syndrome.’’ Researchers have suggested that a cause for the correlation between different behaviors might lie in the neuroendocrine system. In this study, we examined the relationships between aggressiveness (a fish’s readiness to perform gill display to its mirror image) and each of boldness (the readiness to emerge from a shelter), exploratory tendency (the readiness to approach a novel shelter), and learning performance (the probability of entering the correct reservoir in a T-maze test) in a mangrove rivulus, Kryptolebias marmoratus. We explored the possibility that the relationships between them arise because these behaviors are all modulated by cortisol and testosterone. We also tested the stability of the relationships between these behaviors shortly after using a winning or losing experience to alter individuals’ aggressiveness. The results were that aggressiveness correlated positively with boldness and the tendency to explore, and that these three behavioral traits were all positively correlated with pre-experience testosterone levels. Aggressiveness and boldness also positively correlated with pre-experience cortisol levels; exploratory tendency did not. The relationship between aggressiveness and boldness appeared to be stronger than that between either of them and exploratory tendency. These results suggest that testosterone and cortisol play important roles in mediating the correlations between these behavioral traits. Learning performance was not significantly correlated with the other behavioral traits or with levels of testosterone or cortisol. Recent experience in contests influenced individuals’ aggressiveness, tendency to explore, and learning performance but not their boldness; individuals that received a winning experience were quicker to display to their mirror image and performed better in the learning task but were slower to approach a novel object than were individuals that lost. Contest experience did not, however, significantly influence the relationships between aggressiveness and any of boldness, exploratory tendency, or learning performance. The results show that the individual components of a suite of correlated behaviors can preserve a flexibility to respond differently to environmental stimuli.

Recent contest experience can influence an individual’s behaviour in subsequent contests. When the probability of winning a subsequent contest is used to quantify experience effects, a loser effect usually lasts longer than a winner effect. This conclusion, however, may be caused by this probability understating the persistence of the influence of a winning experience on contest decisions. Using Kryptolebias marmoratus, a mangrove killifish, as the study organism, we investigated whether different conclusions about the relative persistence of winning and losing experiences would be reached when different aspects of contest behaviour (probability of initiating attacks, probability of winning non-escalated and escalated contests, escalation rate and contest duration) were measured. The results indicated that the apparent persistence of the effect of winning or losing experiences varied with the behaviour studied. When the likelihood to initiate attacks was used, no winner effect was detected while the loser effect lasted for

This study used The Canine Behavioral Assessment and Research Questionnaire (C-BARQ) and regression models to explore the relative importance of dog and owner characteristics, living environment and owner–dog interaction to household dogs' aggressiveness towards strangers, owners and other dogs. Exploratory factor analysis revealed 10 interpretable factors from the Chinese translation of C-BARQ: stranger-directed aggression, owner-directed aggression, dog-directed aggression, social fear, nonsocial fear, separation-related behavior, attachment or attention-seeking behavior, trainability, excitability and pain sensitivity. The factor structure of our study largely resembled that reported in Hsu and Serpell (2003) and van den Berg et al. (2006; Dutch translation of C-BARQ). All factors of the translated C-BARQ have adequate reliability (Cronbach α : 0.74–0.93) and are thus suitable for measuring temperament traits in Taiwan's pet dogs. Intrinsic and environmental variables important to the three aggression subscales were not entirely the same, but breed ( P ≤0.020) and physical punishment ( P ≤0.053) had significant relationships with all of them. Golden Retriever scored the lowest while dogs subjected to physical reprimands scored significantly higher on aggression subscales. In addition, higher scores on stranger-directed aggression were associated ( P ≤0.027) with living in rural areas, in houses with yard space and with more household members and being acquired either as puppies or for guarding purposes. Higher scores on owner-directed aggression were associated ( P ≤0.040) with male and older dogs, being neutered/spayed, having female owners, fewer other dogs in the household and being kept outside the house. Higher scores on dog-directed aggression, on the other hand, were associated ( P ≤0.050) with living in houses with either yard space or more household members and with spending less time with owners. Stranger- and dog-directed aggression had more important intrinsic and environmental variables common to them than did owner-directed aggression, which suggests that aggression towards owners may be regulated by different mechanisms from aggression towards strangers and other dogs. Although no causal relationship between dog aggression and environmental variables can be implied from observational studies, the results of this and other studies lend support to the possibility of reducing dogs' aggressive responses through proper management by owners.

Canine aggression poses serious public health and animal welfare concerns. Most of what is understood about breed differences in aggression comes from reports based on bite statistics, behavior clinic caseloads, and experts’ opinions. Information on breed-specific aggressiveness derived from such sources may be misleading due to biases attributable to a disproportionate risk of injury associated with larger and/or more physically powerful breeds and the existence of breed stereotypes. The present study surveyed the owners of more than 30 breeds of dogs using the Canine Behavioral Assessment and Research Questionnaire (CBARQ), a validated and reliable instrument for assessing dogs’ typical and recent responses to a variety of common stimuli and situations. Two independent data samples (a random sample of breed club members and an online sample) yielded significant differences among breeds in aggression directed toward strangers, owners and dogs (Kruskal–Wallis tests, P < 0.0001). Eight breeds common to both datasets (Dachshund, English Springer Spaniel, Golden Retriever, Labrador Retriever, Poodle, Rottweiler, Shetland Sheepdog and Siberian Husky) ranked similarly, rs = 0.723, P < 0.05; rs = 0.929, P < 0.001; rs = 0.592, P = 0.123, for aggression directed toward strangers, dogs and owners, respectively. Some breeds scored higher than average for aggression directed toward both humans and dogs (e.g., Chihuahuas and Dachshunds) while other breeds scored high only for specific targets (e.g., dog-directed aggression among Akitas and Pit Bull Terriers). In general, aggression was most severe when directed toward other dogs followed by unfamiliar people and household members. Breeds with the greatest percentage of dogs exhibiting serious aggression (bites or bite attempts) toward humans included Dachshunds, Chihuahuas and Jack Russell Terriers (toward strangers and owners); Australian Cattle Dogs (toward strangers); and American Cocker Spaniels and Beagles (toward owners). More than 20% of Akitas, Jack Russell Terriers and Pit Bull Terriers were reported as displaying serious aggression toward unfamiliar dogs. Golden Retrievers, Labradors Retrievers, Bernese Mountain Dogs, Brittany Spaniels, Greyhounds and Whippets were the least aggressive toward both humans and dogs. Among English Springer Spaniels

To determine whether animals assess each other's fighting ability in contests, researchers usually regress contest duration over the sizes of the contestants. The predominant trend in recent studies is for the contest duration to correlate positively with the size of the smaller opponent but to have no obvious relationship with the size of the larger opponent. This indicates that animals make contest decisions based on their own abilities (‘self assessment’) and displaces the once-popular belief that they assess their opponents (‘mutual assessment’). These tests, however, are based on the implicit but never stated assumption that animals adopt only one assessment approach throughout an entire contest. By examining the contest behaviours of a killifish, we show that (1) the fish adopt mutual assessment at earlier stages when deciding whether to escalate the contest from the mutual display to the attack phase and (2) once a contest is escalated, the fish switch to self assessment to decide how long to escalate. Our results show that individuals may adopt multiple assessment approaches in one contest; contest behaviours in different stages (where applicable) of a contest should be analysed separately to better elucidate animal contest assessment strategies.

Despite the dog’s long mutualistic association with humans, global attitudes toward the species, Canis familiaris, are exceedingly diverse, ranging from overwhelmingly positive in most Western countries to predominantly negative in many developing nations. Since attitudes are important predictors of dog-related behavior, knowledge of the forces and factors that affect people’s attitudes to dogs can make an important contribution to improving dog-human relations, global public health, and canine welfare. This chapter explores some of the key factors influencing dog-related attitudes and behavior, with particular reference to the results of a case study of attitudes to dogs in Taiwan. The findings suggest that people’s attitudes to dogs involve both affective/emotional and instrumental/practical components, and that a significant minority of people in Taiwan are opposed to the killing/euthanasia of unwanted dogs. The most important determinant of both positive affective attitudes to dogs and opposition to killing/euthanasia was the experience of growing up with household dogs. The significance of these and other findings are discussed from the perspective of animal attitude development, and dog welfare and population management.

In a previous study of canine temperament (Hsu and Serpell 2003), a distinct “trainability” factor was identified, characterized by a dog's willingness to attend to its owner and obey simple comman...

Contest decisions are influenced by the outcomes of recent fights (winner–loser effects). Steroid hormones and serotonin are closely associated with aggression and therefore probably also play important roles in mediating winner–loser effects. In mangrove rivulus fish, Kryptolebias marmoratus , individuals with higher testosterone (T), 11-ketotestosterone and cortisol levels are more capable of winning, but titres of these hormones do not directly mediate winner–loser effects. In this study, we investigated the effects of winning/losing experiences on brain expression levels of the receptor genes for androgen (AR), oestrogen α/β (ER α/β ), glucocorticoid (GR) and serotonin (5-HT 1A R). The effect of contest experience on AR gene expression depended on T levels: repeated losses decreased, whereas repeated wins increased AR gene expression in individuals with low T but not in individuals with medium or high T levels. These results lend strong support for AR being involved in mediating winner–loser effects, which, in previous studies, were more detectable in individuals with lower T. Furthermore, the expression levels of ER α/β , 5-HT 1A R and GR genes were higher in individuals that initiated contests against larger opponents than in those that did not. Overall, contest experience, underlying endocrine state and hormone and serotonin receptor expression patterns interacted to modulate contest decisions jointly.

Most guide and service dog organizations would benefit from the development of accurate methods for the early evaluation of canine temperament traits. This paper describes the development and validation of a novel questionnaire method for assessing behavior and temperament in 1-year-old guide dogs. Volunteer puppy-raisers scored a total of 1097 prospective guide dogs on a series of 40 semantic differential-type, behavioral rating scales. Principle components factor analysis of these scores extracted eight stable and interpretable common factors: stranger-directed fear/aggression, non-social fear, energy level, owner-directed aggression, chasing, trainability, attachment, and dog-directed fear/aggression. Three of these eight factors exhibited moderate internal consistency (Cronbach’s α≥0.72), while the reliabilities of the remaining factors were relatively low (Cronbach’s α=0.53–0.61). The eight factors were then validated against the guide dog school’s own criteria for rejecting dogs for behavioral reasons. The results of this analysis confirmed the construct validity of the puppy raisers’ questionnaire assessments of their dogs, and suggested that such methods can provide a useful and accurate means of predicting the suitability of dogs for guiding work. Various modifications to the original questionnaire are proposed in order to enhance its overall reliability.

We examined the effect of prior winning and losing experiences on the initiating and responding strategies of contestants in contests between individuals of Rivulus marmoratus (Cyprinodontidae). Each contestant was given a penultimate and a recent fighting experience approximately 48 and 24 h prior to the dyadic contests, respectively, through randomly selected procedures. Winning and losing experience appeared to influence different types of fighting behaviours. Losing experiences decreased the probability of an individual initiating a confrontation and thus increased its tendency to retreat immediately when challenged. Winning experiences did not affect the probability of initiation, but significantly increased the likelihood of an individual initiating with attacks that effectively deterred its opponents. A substantial proportion (59/153) of individuals retreated immediately when challenged and reduced the number of fights available for examining experience effects on responding strategies at later stages of a contest. None the less, winning experiences consistently increased the likelihood of an individual retaliating by attacking its opponent at various stages of a contest, and eventually increased its probability of escalating a confrontation into physical fights. However, the effects of losing experiences on these responding strategies were undetectable. Recent experiences significantly affected all fighting behaviours examined, but penultimate experiences significantly affected only the tendency to initiate a confrontation with attacks and the likelihood of escalation. These results indicated that prior experiences had the longest lasting effect on the potentially most costly fighting behaviour. Prior experiences influenced the outcome of nonescalated contests as well as the probability of escalation, but did not significantly affect the outcome of escalated contests. These results are consistent with the hypothesis that prior experiences modify the information that an individual has about its fighting ability but do not alter its actual fighting ability and that actual fighting ability becomes the more important influence on outcomes of escalated contests.

Aggression plays an important role in animal contests, but the extent to which aggression correlates with dominance has been a topic of much debate. The relationship between aggression and dominance ability in the hermaphroditic fish, Rivulus marmoratus, was investigated using three standard protocols, the mirror test (Mi), model test (Mo), and standard opponent test (So). In each, display latency, attack latency, and biting frequency were quantified for a test individual towards its opponent. The general rank-order for eliciting strength of the three different stimuli was Mi > So > Mo. The relationships between the individual indices from the standard tests and three dyadic contest variables, initiator of display, initiator of attack, and winner, were analysed in contests between previously tested pairs to ascertain how well the standard protocols predicted dyadic contest behaviour/outcome. Display and attack latencies in the standard tests did not predict the level of analogous combat behaviour. Biting frequency differences between individuals in a pair in the So and Mo tests as well as display latency differences in the Mi test contributed to predictions of contest outcome. The individual that scored higher, relative to its opponent, won a significantly greater proportion of the bouts. These findings demonstrate the importance of relative differences in aggression in determining dominance. However, the predictive value of standard test behaviour is test-specific and, based on the available literature, depends on both the species used and the context in which they are employed.

An important question in state-dependent behaviour is how multiple influences on state are integrated to determine current behaviour. Aggressive behaviour is known to be affected by a prior contest experience. Nevertheless, whether and how multiple prior fighting experiences are integrated into a fighting decision remain unexplored. In this study, individuals of Rivulus marmoratus (Cyprinodontidae), a hermaphroditic fish, were given different combinations of two prior fighting experiences to investigate: (1) the effect of penultimate experiences on the probability of winning a subsequent contest; (2) the relative effect of a recent win and loss; and (3) whether the effect of a winning experience was as short lived as observed in other species. Penultimate and recent fighting experiences were given to the test fish approximately 48 and 24 h prior to the dyadic contests, respectively. From the results of the five types of contests staged, we conclude that: (1) penultimate fighting experiences had a significant effect on the probability of winning a subsequent contest; (2) a more recent experience had a more pronounced effect than an earlier experience, which suggested that the effect of a fighting experience would decay and/or the effect of a recent experience would interfere with the effect of an earlier experience; (3) no asymmetric effect between a winning experience and a losing experience was detected; and (4) the effect of both a winning and a losing experience lasted for at least 48 h in R. marmoratus which was the maximum time tested in these experiments. The possible reasons for the differences in results among studies of experience effects on contest outcomes are discussed. Copyright 1999 The Association for the Study of Animal Behaviour.

Many animals modify behavioural decisions based on information they have previously acquired. Contest behaviour is often affected by previous contest experiences: individuals behave more and less aggressively after a victory and defeat, respectively (winner/loser effect). Individuals in the field sometimes encounter multiple competitors in quick succession, but whether these experiences interact to influence each other’s importance is unclear. We tested five hypotheses for experience interaction (no interaction, retroactive interference, proactive interaction, reinforcement and diminishing returns) using Kryptolebias marmoratus. Focal individuals were paired up with opponents having the same 1-month contest outcome (1 month before the experiment), as this difference in actual or perceived fighting ability has been shown to affect the fish’s response to new experiences. We gave the focal individual of a pair a winning or losing experience on day 1. Then both fish of the pair received the same winning, losing or no-contest experience on day 2. Then we organised fights between the two. The effect of a day-1 losing experience did depend on the fish’s actual or perceived fighting ability: one-month losers readily showed loser effects from the day-1 losing experience, irrespective of the day-2 experience (i.e. no interaction between day-1 and day-2 experiences). One-month winners, however, only showed loser effects from a day-1 losing experience when the day-2 experience was also a loss (i.e. reinforcement). Day-1 winning experiences did not interact with day-2 experiences in 1-month losers or winners. Therefore, multiple experiences sometimes reinforce each other, but how they combine to influence behaviour depends on an individual’s actual or perceived fighting ability.

Experience in aggressive contests often affects behaviour during, and the outcome of, later contests. This review discusses evidence for, variations in, and consequences of such effects. Generally, prior winning experiences increase, and prior losing experiences decrease, the probability of winning in later contests, reflecting modifications of expected fighting ability. We examine differences in the methodologies used to study experience effects, and the relative importance and persistence of winning and losing experiences within and across taxa. We review the voluminous, but somewhat disconnected, literature on the neuroendocrine mechanisms that mediate experience effects. Most studies focus on only one of a number of possible mechanisms without providing a comprehensive view of how these mechanisms are integrated into overt behaviour. More carefully controlled work on the mechanisms underlying experience effects is needed before firm conclusions can be drawn. Behavioural changes during contests that relate to prior experience fall into two general categories. Losing experiences decrease willingness to engage in a contest while winning experiences increase willingness to escalate a contest. As expected from the sequential assessment model of contest behaviour, experiences become less important to outcomes of contests that escalate to physical fighting. A limited number of studies indicate that integration of multiple experiences can influence current contest behaviour. Details of multiple experience integration for any species are virtually unknown. We propose a simple additive model for this integration of multiple experiences into an individual's expected fighting ability. The model accounts for different magnitudes of experience effects and the possible decline in experience effects over time. Predicting contest outcomes based on prior experiences requires an algorithm that translates experience differences into contest outcomes. We propose two general types of model, one based solely on individual differences in integrated multiple experiences and the other based on the probability contests reach the escalated phase. The difference models include four algorithms reflecting possible decision rules that convert the perceived fighting abilities of two rivals into their probabilities of winning. The second type of algorithm focuses on how experience influences the probability that a subsequent contest will escalate and the fact that escalated contests may not be influenced by prior experience. Neither type of algorithm has been systematically investigated. Finally, we review models for the formation of dominance hierarchies that assume that prior experience influences contest outcome. Numerous models have reached varied conclusions depending on which factors examined in this review are included. We know relatively little about the importance of and variation in experience effects in nature and how they influence the dynamics of aggressive interactions in social groups and random assemblages of individuals. Researchers should be very active in this area in the next decade. The role of experience must be integrated with other influences on contest outcome, such as prior residency, to arrive at a more complete picture of variations in contest outcomes. We expect that this integrated view will be important in understanding other types of interactions between individuals, such as mating and predator-prey interactions, that also are affected significantly by prior experiences.