Individual Differences In Exploratory Behavior Research Articles

Exploratory individuals are bolder in Great Tit: Correlation between personality and antipredator behavior

AbstractConsistent individual behavioral differences from other members of local populations are called animal personality, and a suite of these correlated behaviors generates a behavioral syndrome. Differential selection patterns among personality types can be largely influenced by predatory behavior. Prey has a large arsenal of antipredator behaviors at their disposal; However, how closely these behaviors are linked to personality is almost unknown. Using a social model species, the Great Tit, Parus major, we investigated whether antipredator behavior in response to predators is correlated with personality. First, we determined if individual differences in exploratory behavior were consistent across trials, that is, whether they were repeatable. Second, we looked into how antipredator behavior was correlated to personality. Individuals were subjected to two repeated trials of standard personality assays followed by an alternative control (Rock Pigeon, Columba livia domestica) and predator display (Eurasian Sparrowhawk, Accipiter nisus) treatment. We found that exploratory behavior was repeatable across trials and had a greater tendency for positive correlation with antipredator behavior when a predator model was displayed. Individuals that swiftly explored novel environments were slower to react to predators than those who explored the novel room slowly. As a result, our findings provide some of the first experimental evidence for a link between exploratory and antipredator behavior, suggesting that personality traits may impact individual fitness.

An updating-based working memory load alters the dynamics of eye movements but not their spatial extent during free viewing of natural scenes

The relationship between spatial deployments of attention and working memory load is an important topic of study, with clear implications for real-world tasks such as driving. Previous research has generally shown that attentional breadth broadens under higher load, while exploratory eye-movement behaviour also appears to change with increasing load. However, relatively little research has compared the effects of working memory load on different kinds of spatial deployment, especially in conditions that require updating of the contents of working memory rather than simple retrieval. The present study undertook such a comparison by measuring participants’ attentional breadth (via an undirected Navon task) and their exploratory eye-movement behaviour (a free-viewing recall task) under low and high updating working memory loads. While spatial aspects of task performance (attentional breadth, and peripheral extent of image exploration in the free-viewing task) were unaffected by the load manipulation, the exploratory dynamics of the free-viewing task (including fixation durations and scan-path lengths) changed under increasing load. These findings suggest that temporal dynamics, rather than the spatial extent of exploration, are the primary mechanism affected by working memory load during the spatial deployment of attention. Further, individual differences in exploratory behaviour were observed on the free-viewing task: all metrics were highly correlated across working memory load blocks. These findings suggest a need for further investigation of individual differences in eye-movement behaviour; potential factors associated with these individual differences, including working memory capacity and persistence versus flexibility orientations, are discussed.

Exploratory behavior is linked to stress physiology and social network centrality in free-living house finches (Haemorhous mexicanus)

Animal personality has been linked to individual variation in both stress physiology and social behaviors, but few studies have simultaneously examined covariation between personality traits, stress hormone levels, and behaviors in free-living animals. We investigated relationships between exploratory behavior (one aspect of animal personality), stress physiology, and social and foraging behaviors in wild house finches (Haemorhous mexicanus). We conducted novel environment assays after collecting samples of baseline and stress-induced plasma corticosterone concentrations from a subset of house finches. We then fitted individuals with Passive Integrated Transponder tags and monitored feeder use and social interactions at radio-frequency identification equipped bird feeders. First, we found that individuals with higher baseline corticosterone concentrations exhibit more exploratory behaviors in a novel environment. Second, more exploratory individuals interacted with more unique conspecifics in the wild, though this result was stronger for female than for male house finches. Third, individuals that were quick to begin exploring interacted more frequently with conspecifics than slow-exploring individuals. Finally, exploratory behaviors were unrelated to foraging behaviors, including the amount of time spent on bird feeders, a behavior previously shown to be predictive of acquiring a bacterial disease that causes annual epidemics in house finches. Overall, our results indicate that individual differences in exploratory behavior are linked to variation in both stress physiology and social network traits in free-living house finches. Such covariation has important implications for house finch ecology, as both traits can contribute to fitness in the wild.

Some like it varied: Individual differences in preference for feed variety in dairy heifers

Motivation to explore is believed to be widespread among animals, but exploratory behaviour varies within populations. Offering variety in feed is one simple way of allowing intensively housed dairy cattle to express exploratory foraging behaviour. Individuals’ exploration of different feed types, as with other new stimuli, likely reflects a balance between exploratory motivation and fear of novelty. We tested the degree to which Holstein heifers (n=10) preferred variety in feed vs. a constant, high quality mixed ration, by first providing varying types of forages and then varying flavours of mixed feed. We also investigated individual differences in exploratory behaviour by measuring switching between feed bins. Individual consistency in preferences was assessed between tests, and longer-term consistency was evaluated by comparing these results with behaviour in novel object and novel feed tests before weaning. On average, the heifers preferred the constant, familiar feed (spending on average just 20% of their time at varied feed bins), but this preference varied among individuals (from 0 to 46% of time eating in the forage trial, and 0–93% in the flavour trial). Preference for varied forages correlated positively with intake of novel feed as calves (rs=0.72, n=9). Preference for varied flavours showed a negative correlation with latency to approach a novel object (rs=−0.65). It thus appears that preference for variety and exploratory foraging behaviour reflect consistent personality traits. These results suggest that offering novel feeds on a rotating schedule as a supplement to the regular diet may be an effective form of enrichment for at least some individuals within a herd.

Exploring novelty: a component trait of behavioural syndromes in a colonial fish.

Individual differences in exploratory behaviour have been shown to be consistent across contexts and suggested to be part of behavioural syndromes in a diversity of species, including fish. Exploration has also been shown to be a key factor in understanding complex ecological processes such as sexual selection and cooperation. Another important question in ecology is why animals breed in colonies. Exploration syndromes, by affecting prospecting behaviour, dispersal and public information use may also contribute to our understanding of coloniality. This study aims at investigating whether an exploration syndrome exists in a colonial fish species, Neolamprologus caudopunctatus. Individuals of this species were subjected to two consecutive tests, a novel environment and a novel object test. Results show that more explorative individuals in a novel environment are also less neophobic in the presence of a novel object, suggesting that the tendency to engage with novelty per se is a consistent trait and part of an exploration syndrome. These results are discussed in light of the contribution of an exploration syndrome to explain colony formation in animals.

Distinctive effects of unpredictable subchronic stress on memory, serum corticosterone and hippocampal BDNF levels in high and low exploratory mice

Stress affects learning and memory processes and sensitivity to stress greatly varies between individuals. We studied behavioral and neurobiological effects of unpredictable subchronic stress (USCS) in two behavioral extremes of mice from the same strain (CF1) selected by their exploratory behavior of the central arena of an open field. The top and bottom 25% explorers were classified as low exploratory (LE) and high exploratory (HE) mice, respectively. The open field task, the novel object recognition task (NOR), sucrose intake and tail suspension task were evaluated in LE and HE groups exposed to USCS for two weeks or control conditions. Also serum corticosterone and hippocampal BDNF and S100B levels were analyzed. Both stressed groups exhibited less exploratory activity when submitted to USCS, but their difference in exploratory behavior remained. This short stress protocol did not induce changes in sucrose intake or immobility in the tail suspension task. Also, LE mice exhibited impaired NOR performance after USCS, whereas HE mice changed their pattern of exploration towards less exploration of the familiar object. HE had lower corticosterone levels than LE mice, but corticosterone levels increased after stress only in HE mice. Hippocampal BDNF in LE was lower than in HE but decreased after USCS only in HE mice, whereas S100B levels were not different between groups and did not change with USCS. In conclusion, our results suggest that individual differences in exploratory behavior in rodents from the same strain influence cognitive and biochemical response to stress.

The effects of novelty-seeking phenotypes and sex differences on acquisition of cocaine self-administration in selectively bred High-Responder and Low-Responder rats

Individual differences in exploratory behavior can predictably influence psychostimulant self-administration behavior. Male rats that exhibit a high degree of locomotor activity in a novel environment (High Responders, HR) will self-administer cocaine more readily than males exhibiting low levels of novelty-induced locomotion (Low Responders, LR). The present experiment investigates the combined influences of the sex of an individual and individual phenotypes in novelty-induced locomotion to predispose animals to acquire cocaine self-administration behavior, in male and female rats selectively bred for the HR–LR phenotypes. We first established that HR females, like their male counterparts, exhibit a dramatically greater locomotor response to novelty and less anxiety-like behavior than do LR females. While locomotor behavior was subtly influenced by estrous stage, with both HR and LR females showing increased activity during metestrus and diestrus compared to proestrus and estrus, the effect did not obscure HR–LR differences. When male and female HR–LR animals were trained to self-administer cocaine (2 h/day, 5 days/wk × 3 wk, 0.2 mg cocaine/kg/infusion), HR males and females acquired cocaine self-administration significantly faster than their LR counterparts. Furthermore, HR females self-administered significantly more cocaine than all other groups. In conclusion, female rats, like males, exhibit HR–LR phenotypes that predict rapidity of acquiring cocaine self-administration. Moreover, HR females self-administer more cocaine than HR males and both LR groups.

Cerebral oxidative metabolism in rats with high and low exploratory activity

To reveal brain regions most significantly related to individual differences in exploratory behaviour, oxidative metabolism was measured by cytochrome c oxidase histochemistry in 2 months old Wistar rats with persistently high (HE) or low (LE) exploratory activity in a novel environment. LE-rats had significantly higher levels of oxidative metabolism in dorsal raphe and inferior colliculi. In contrast, HE-rats had higher metabolic activity in entorhinal cortex. In conclusion, rats with different exploratory styles differ in underlying cerebral activity as measured via oxidative metabolism in regions implicated in defensive behaviours and cognitive processing of sensory stimuli.

INDIVIDUAL BEHAVIOURAL CHARACTERISTICS AND DOMINANCE IN AVIARY GROUPS OF GREAT TITS

In previous work we have shown that juvenile male great tits Parus major show consistent behavioural differences in exploratory and aggressive behaviour. Fast and superficial explorers (FE) won from slow and thorough explorers (SE) during controlled pair-wise confrontations in small cages. The present study assesses the relationship between early exploratory behaviour and later dominance in aviary groups of juvenile male great tits; such groups might approach natural conditions better than 'simple' pair-wise confrontations. Observations of nine aviary groups showed that a stable hierarchy is only established after a first dynamic phase of several days with many dominance shifts and a peak in number of interactions. In seven other aviary groups we determined the dominance relationships between FE and SE. In a stable hierarchy, SE had on average a significantly higher dominance score than FE. This finding contrasts our previous results in pair-wise confrontations. However, on the first day in the aviary, FE had on average a higher dominance score and initiated more fights than SE. This agrees with our previous results and indicates a gradual development of the situation in the stable hierarchy. Behavioural observations indicate that during this development, FE took more risks in their fighting behaviour and had more difficulty to cope with defeat than SE. In the stable hierarchy they either won or lost from all SE. SE were more cautious and had intermediate dominance scores in the stable hierarchy. These differences in fighting behaviour and the role of individual differences in exploratory behaviour and in coping with defeat are discussed as possible causes for the unexpected results of this study.

Individual differences in exploratory behavior during infancy

Individual differences in exploratory behavior during infancy

Exploration, Aggressive Behaviour and Dominance in Pair-Wise Confrontations of Juvenile Male Great Tits

In the development of social dominance, constitutional behavioural characteristics may play an important role apart from morphological traits. Previous work has shown that juvenile male great tits Parus major differ consistently in their early exploratory behaviour and can be classified as fast and superficial explorers or slow and thorough explorers. This study investigated whether these individual differences in exploratory behaviour are related to aggressive behaviour, and whether this affects dominance. In an experimental set-up, pair-wise fights were observed. The obtained data were corrected for possible influences of morphological traits. Consistent individual differences in aggressive behaviour were found, indicating that juvenile great tits can be characterised by that behaviour. Fast explorers started more fights than slow explorers, and birds that started more fights also won more fights. An additional experiment with pairs of fast and slow explorers confirmed that fast explorers won more fights than slow explorers. In conclusion, we demonstrated that individual differences in exploratory behaviour are related to aggressive behaviour, which affects dominance. The striking agreement of these findings with studies of rodents and pigs is discussed. It is suggested that the behaviour of fast explorers agrees with an active style of coping with stress, while the behaviour of the slow explorers resembles a passive coping style.

Use of space by juveniles in relation to their postnatal range, mother, and siblings: an example in the wild boar Sus scrofa L.

Eight juvenile (3–8 months) wild boars belonging to two separate litters, and the mother of each litter, were radiolocated daily. The position of an individual juvenile at the time of each location was classified according to its association with its postnatal range, its mother, and its siblings. Preliminary analysis showed that location relative to the postnatal range was independent of association with the mother and siblings, while association with the mother was positively correlated. Although a degree of attachment to their postnatal range persisted in juveniles, surrounding areas were used preferentially. Juveniles were equally likely to be located in the presence of their mother as without her, but they generally separated from their mother during exploratory phases outside the postnatal range. Individual differences in exploratory behaviour occurred between juveniles from the same litter.

Individual differences in exploratory behavior in the second year of life

For children in their second year, exploration is an inherently social phenomenon with fundamental implications for learning about the animate and inanimate world. This article examines how 15-month-old children spontaneously involve their mothers in their exploration of a novel task in an unstructured setting. Forty-six 15-month-olds were presented with a novel exploration task with their mothers present but uninvolved. The task consisted of a box with 15 clear plastic drawers each containing a novel toy. Types of bids to mothers, children's affect, and exploratory behaviors were coded. In the absence of active maternal cues, 15-month-old children quickly and frequently involved their mothers in their exploratory efforts, and at least half of the bids were accompanied by positive affect. Active bids to mother (walking or extending a toy) were associated with more manipulation of novel toys, whereas passive bids such as looking were related to less active exploration of toys and more visual inspection of the task stimuli. Furthermore, the earlier any type of bid to mother, the quicker children approached novel toys. Finally, there were notable sex differences both in children's bids to their mothers and in their approach to the task. While exploring, girls made more active bids for physical contact with their mothers. On the other hand, girls spent more time than boys visually examining the box itself without touching, but boys spent more time than girls exploring and touching the box. These results are discussed in terms of how mothers and children mutually contribute to children's interest in novel exploration.

Parents and Exploration: The Effect of Context on Individual Differences in Exploratory Behavior

HENDERSON, BRUCE B. Parents and Exploration: The Effect of Context on Individual Differences in Exploratory Behavior. CHILD DEVELOPMENT, 1984, 55, 1237-1245. The effect of social context on individual differences in children's exploratory behavior was examined in 3 studies. In Study 1, 68 high-, moderate-, and low-exploratory children 3-6 years of age identified by their responses to a battery of novel tasks explored novel toys with their parents. There were no differences in exploration as a function of parent present or assessment level of exploration. Mothers and fathers behaved similarly in the sessions. Study 2 investigated the absence of assessment-level differences with 38 preschool children exploring similar sets of novel toys with their mothers and with an experimenter. Assessment-level differences were obtained only in the experimenter-child session. Study 3 was conducted with 55 children ages 3-6 to determine if maternal presence or mother-child interaction was responsible for the absence of assessment-level effects in Studies 1 and 2. Assessment-level differences in exploratory behavior were found only in sessions where the mother was passive. The implications of the studies for understanding the nature of individual differences in exploration and social influences on exploration are discussed in terms of Vygotsky's notion of the zone of proximal development.

Physiological and biochemical correlates of individual differences in behavior of wolf cubs.

Abstract In two litters of wolf cubs, individual differences in exploratory behavior, prey killing ability and social dominance were demonstrated, test scores showing a high degree of correlation as shown in an earlier study (Fox, 1972). Subjects with high, intermediate and low scores were selected for heart rate determinations monitored biotelemetrically under a test sequence designed to evaluate emotional reactivity. After these temperament and emotional-autonomic reactions had been determined, cubs were subjected to confinement and handling stress, blood samples being taken serially for plasma cortisol estimations. This treatment was repeated after ACTH injection. These findings demonstrate a marked difference in sympathetic tone and adrenal responsiveness to stress between high and low ranking cubs. High ranking cubs showed a greater sympathetic tone (higher resting EKG) and the adrenal-pituitary response to stress and ACTH treatment was of greater magnitude than in subordinates. Subjects of middle rank and with intermediate behavioral scores had a higher sympathetic tone than subordinates and under stress had a shorter latency and greater magnitude of cortisol secretion than either their higher or lower ranking peers.

Total home-cage activity as a function of the estrous cycle and wheel running in the rat

Activity was time-sampled and examined with reference to three variables: the estrous cycle, access to running wheels, and individual differences in exploratory behavior. Total activity paralleled exploratory behavior as the latter fluctuated with the estrous cycle. When behaviors were averaged over days, running did not affect total activity. Implications for a regulation of total activity were discussed.