What is the tree structure of personality?
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), the authors evaluate the status of personality traits in animals. The animal literature provides strong evidence that personality does exist in animals. That is, personality ratings of animals: (a) show strong levels of interobserver agreement, (b) show evidence of validity in terms of predicting behaviors and real-world outcomes, and (c) do not merely reflect the implicit theories of observers projected onto animals. Although much work remains to be done, the preliminary groundwork has been laid for a comparative approach to personality.
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IntroductionPersonality characteristics have been examined in a broad range of nonhuman species including chimpanzees, rhesus monkeys, ferrets, hyenas, rats, sheep, rhinoceros, hedgehogs, zebra finches, garter snakes, guppies, and octopuses (for a full review, see Gosling, 2001). Such research is important because animal studies can be used to tackle questions that are difficult or impossible to address with human studies alone. By reaping the benefits of animal research, a comparative approach to personality can enrich the field of human personality psychology, providing unique opportunities to examine the biological, genetic, and environmental bases of personality, and to study personality development, personality-health links, and personality perception. However, all of these benefits hinge on the tenability of the personality construct in non-human animals. Thus, the purpose of the present paper is to address a key question in the animal domain: is personality real? That is, do personality traits reflect real properties of individuals or are they fictions in the minds of perceivers? Thirty years ago, the question of the reality of personality occupied the attention of human-personality researchers, so our evaluation of the comparative approach to personality draws on the lessons learned in the human domain. Mischel’s (1968) influential critique of research on human personality was the first of a series of direct challenges to the assumptions that personality exists and predicts meaningful real-world behaviors. Based on a review of the personality literature, Mischel (1968) pointed to the lack of evidence that individuals’ behaviors are consistent across situations (Mischel & Peake, 1982). Over the next two decades, personality researchers garnered substantial empirical evidence to counter the critiques of personality. In an important article, Kenrick and Funder (1988) carefully analyzed the various arguments that had been leveled against personality and summarized the theoretical and empirical work refuting these arguments. The recent appearance of studies of animal personality has elicited renewed debate about the status of personality traits. Gosling, Lilienfeld, and Marino (in press) proposed that the conditions put forward by Kenrick and Funder (1988) to evaluate the idea of human personality can be mobilized in the service of evaluating the idea of animal personality. Gosling et al. (in press) used these criteria to evaluate research on personality in nonhuman primates. In the present paper, we extend their analysis to the broader field of comparative psychology, considering research on nonhuman animals from several species and taxa. Kenrick and Funder’s paper delineates three major criteria that must be met to establish the existence of personality traits: (1) assessments by independent observers must agree with one another; (2) these assessments must predict behaviors and real-world outcomes; and (3) observer ratings must be shown to reflect genuine attributes of the individuals rated, not merely the observers’ implicit theories about how personality traits covary. Drawing on evidence from the animal-behavior literature, we evaluate whether these three criteria have been met with respect to animal personality. Section snippetsCriterion 1: Independent assessments must agreeIf individual differences in personality exist and can be detected, then independent observers should agree about the relative standing of individuals on personality traits. The preponderance of evidence supports the conclusion that humans agree strongly in their ratings of other humans; studies typically elicit interobserver agreement correlations in the region of .50 (e.g., Funder, Kolar, & Blackman, 1995; McCrae, 1982), and provide a benchmark by which judgments of animals can be evaluated. Criterion 2: Assessments must predict behaviors and real-world outcomesUltimately, for personality traits to have value, they must predict behaviors and real-world outcomes. Thus, one of Mischel’s (1968) most pointed criticisms of personality was to argue that personality traits rarely predict behaviors or real-world outcomes at meaningful levels, with trait-behavior correlations rarely exceeding .30. Mischel’s critique prompted two major responses. First, researchers argued that trait–behavior correlations should be measured using aggregates of behavior codings Criterion 3: Ratings must reflect attributes of targets, not observer’s implicit personality theoriesIn recent years, several studies of personality structure in animals have been published (see Gosling & John, 1999 for a review); each of these studies has identified a number of broad dimensions, which often resemble the dimensions found in studies of humans. These findings could be taken as evidence that animals have personality. However, it is possible that observers are not detecting the true structure of personality traits in animals, but are instead simply “filling in the blanks” using SummaryPersonality research in animals fares relatively well when held to the standards expected of human personality research—there is strong evidence that personality does exist in animals. That is, personality ratings of animals show strong levels of interobserver agreement, and these assessments show evidence of validity in terms of predicting behaviors and real-world outcomes, such as susceptibility to disease progression. Finally, these assessments do not merely reflect the implicit theories of References (32)
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On predicting most of the people much of the timeJournal of Personality and Social Psychology(1979) Aggregation and beyond: Some basic issues on the prediction of behaviorJournal of Personality(1983) Agreement among judges of personality: Interpersonal relations, similarity, and acquaintanceJournal of Personality and Social Psychology(1995) Behavior as a function of the situationJournal of Personality and Social Psychology(1983) Personality dimensions in Spotted Hyenas (Crocuta crocuta)Journal of Comparative Psychology(1998) 2022, Applied Animal Behaviour Science Show abstractNavigate Down Subjective equine personality questionnaires have the potential to predict a range of industry-relevant outcomes including fear reactivity, compliance with human cues, pain expression and susceptibility to stereotypies, in a time- and cost-efficient manner. However, to produce meaningful measures of target animals’ behavioural tendencies, subjective personality assessment tools must satisfy four criteria: internal consistency, predictive validity, inter-rater reliability, and test-retest reliability. The Equine Personality Test (EPT) has been developed to assess horses on five personality factors based on trait ratings from a familiar observer. While the EPT has been shown to have predictive validity, it has not been assessed for internal consistency, inter-rater reliability or test-retest reliability. To this end, three experienced primary caregivers and three riding instructors assessed 25 familiar horses using the EPT. The internal consistency, inter-rater reliability and test-retest reliability of the five subscales of the EPT were investigated using Cronbach’s α and intra-class correlation (ICC) analyses. The Agreeableness, Neuroticism, Extroversion and Gregariousness towards People subscales had high Cronbach α and inter-rater and test-retest ICC coefficients (α > 0.7; ICC>0.8). By contrast, the Gregariousness towards Horses subscale had low Cronbach α (α = 0.39) and inter-rater ICC coefficient (ICC=0.498), and an adequate test-retest ICC coefficient (ICC=0.784). Primary caregivers had higher ICC coefficients than instructors for most subscales and questionnaire items. The EPT therefore provides internally consistent and highly reliable measures of Agreeableness, Neuroticism, Extroversion, and Gregariousness towards People in equines, although measures of Gregariousness towards Horses should be interpreted with caution. The reliability of EPT scores can be further improved by targeting primary caregivers as raters. Taken together with previous findings demonstrating predictive validity for the questionnaire, these results contribute to making the EPT the only subjective equine personality questionnaire to have been checked against all four criteria of a valid and reliable personality assessment tool. This positions the EPT as a highly relevant equine personality assessment tool that may be used to predict behavioural tendencies in industry or research settings alike. 2022, Applied Animal Behaviour Science Show abstractNavigate Down Guide dogs are one type of assistance dogs in Japan that help individuals who are visually impaired. The qualification of candidate dogs is judged based on temperament and health. Previously, our group showed that ‘Distraction’ was the most influential behavioural trait for qualification at the Japan Guide Dog Association (JGDA). In this study, to examine the underlying behavioural sub-traits associated with ‘Distraction’, we conducted behavioural tests focusing on the overall activity of candidate dogs and the degree to which they paid attention to a handler. The subjects were 59 candidate guide dogs (Labrador Retrievers) born and reared at the JGDA. At 7 weeks of age, we measured behavioural responses under the following situations: Isolation (5 min), Experimenter Entering (5 min), Elevation (30 s), and Restraint (30 s). At 14 months of age (during the second month of training), we measured behavioural responses and physiological responses (heart rate) under the following situations: Kennel (10 min), Isolation (5 min), and Experimenter Entering (5 min). When the dogs were 15 months of age (during the third month of training), we asked experienced trainers to complete a questionnaire to calculate the ‘Distraction’ score. We used multiple regression analysis (MRA) to examine the association between the ‘Distraction’ score, behavioural responses, and physiological responses at 7 weeks and 14 months of age. We found that dogs with lower ‘Distraction’ scores, i.e., less distractable, spent more time engaged in “struggle” behaviour in the Elevation condition at 7 weeks of age. At 14 months of age, they spent less time engaged in “active movement” and had a higher heart rate in the Isolation condition, and they spent more time engaged in “gaze” behaviour in the Experimenter Entering condition. According to the coefficient of determination and the standardized coefficients in the MRA, “gaze” in the Experimenter Entering condition had a comparatively large effect. Therefore, attention towards a handler, interpreted as “gaze”, appears to be an important underlying behavioural sub-trait for ‘Distraction’ compared with overall activity. These findings are expected to contribute to improving the training efficiency of guide dogs through the modification of both the training and breeding strategy. 2022, Applied Animal Behaviour Science Show abstractNavigate Down In case of social animals often we can observe dominance hierarchies among the group members around limited resources. Once stabilized, hierarchy can help the access to these resources – in favour of the dominant individuals – without serious conflict or harm. While we can easily identify the limited resources in nature, in case of companion dogs, all essential resources are provided by the owner thus shortcutting competition. While it seems that its original function is not present in companion dogs, dominance hierarchies were still described in dog groups. As everyday competition for essential resources is seldom part of the lives of most companion dogs, our aim was to find what traits might be related to the formation of these hierarchies and the rank of the individuals. We designed an online survey for owners of multiple dogs to assess i) the dominance relationship between the co-habiting dogs via their everyday interactions and ii) their personalities using the Canine Big Five questionnaire. We received responses for 1082 dogs. Four of the five personality traits had a significant association with dominance: while more extroverted (p = 0.0003), conscientious (p = 0.0006), and open (p = 0.0088) dogs scored higher on dominance, more agreeable dogs scored lower (p < 0.0001). In accordance with previous studies, we also found that older dogs tend to be more dominant (p = 0.001). We also found a small but not negligible number of dog-pairs that had no difference in their dominance scores. Although our study is not suitable for detecting causality, the results show that there is a complex association between owner-perceived dominance and personality in group-living companion dogs. 2017, Applied Animal Behaviour Science Citation Excerpt : As this study aimed at obtaining knowledge on the population level, and the respondents were well informed of this, as well as the respondents being anonymous, not gaining personal profit or receiving any information on individual animals, ratings done by the respondents are considered to be their honest perception of the objective horses. In general, as summarized by Gosling and Vazire (2002), personality ratings of animals show high level of agreement between observers, validity through accordance between predicted behaviours and real-world outcomes and low degree of anthropomorphism. The reliability of behaviourally defined adjectives was studied by Lloyd et al. (2007) by looking at the variance and the bias of the ratings, assessed from three independent observers. Show abstractNavigate Down To increase the populations of the Norwegian horse breeds, it is desirable to improve their competitive edge in the market. One of the declared strengths of these populations are their robust temperament, which has not been described sufficiently to be utilized for breeding purposes. A horse personality questionnaire (HPQ), with grading of 43 behaviourally defined adjectives, was analysed with a factor analysis to condense the temperament of the four Norwegian breeds into main temperamental factors. The analysis consisted of 1018 horses and the respondents was in general handlers or owners of the objective horse. The Fjord horse, the Dole horse and the Nordland/Lyngen shared the same five factors in the analysis; ‘anxiousness’, ‘agreeableness’, ‘conscientiousness’, ‘openness’ and ‘dominance’. The Norwegian coldblooded trotter shared the same five factors, but in addition had a factor identified as ‘excitability’. In total, the factors explained a maximum of 44% of the variance, which is somewhat less than other studies using the HPQ or similar. An expansion of number of adjectives compared to earlier studies, with skewness in which factor they load on to and more non-loading adjectives, could be an explanation of this. The use of HPQ has contributed to simplify the phenotypic landscape, but for future development of assessing temperamental traits for breeding purposes, a horse personality questionnaire is not recommended, as it is probably highly influenced by personal preferences or possible benefits of the owner. The alternative is impartial observers unknown to the horses, demanding a test arena for the horses, where the observers can base their ratings on the horses’ performances. 2017, Journal of Veterinary Behavior: Clinical Applications and Research Citation Excerpt : Historically rating an animal's personality traits has been considered subjective, although it does allow for assessment to be made over a relatively long period (Gosling, 2001). Assessing emotional state often makes use of behavioral tests, such as assessing the animal's response when it is exposed to in novel object (Gosling, 2001, Gosling and Vazire, 2002). Both methods have some value and may be seen as complementary (Gosling 2001). Show abstractNavigate Down Effective identification of emotional states in captive big cats by keepers is important for them to be able to reduce the risks of abnormal behavior by providing appropriate enrichment strategies. In an initial study, 29 emotional states in each of 4 cheetahs were rated daily by 5 keepers. Three emotional state domains were identified, apparently associated with “nervousness,” “adventurousness,” and “aggression.” Keepers then rated each cheetah on these domains daily for a mean of 18 days. Consistent differences in scores between keepers and between cheetahs were identified, with “aggression” being the least variable domain. In a second study with 9 tigers and 9 keepers, 4 emotional state domains were similarly identified from keeper ratings, apparently related to “aggression,” “fear,” “vigilance,” and “obedience.” Keeper ratings of these domains before and after the tigers' period in night quarters were used, together with video-recorded behavior in the first and last 90 minutes in night quarters, to evaluate the effect of 3 enrichments, 2 olfactory, 1 physical (coffee essence, fish smears, and palm leaves) offered in the night enclosures. There were no overall differences in the emotional state domains of the tigers between the 3 enrichments, as assessed by the keepers, although the video-records of behavior showed that tigers that received fish smears paced less (37% of time ±3.1%) than those receiving coffee essence (48% of time, ±3.1%) or palm leaves (50 % of time, ±3.1%). It is concluded that keepers can consistently rate big cats' emotions, but it is uncertain whether their ratings are adequate to determine appropriate enrichment strategies for individual felids to minimize abnormal behaviors. 2015, International Encyclopedia of the Social & Behavioral Sciences: Second Edition Show abstractNavigate Down Temperament refers to early-appearing dispositions upon which personality is based, and research on temperament offers an important place to begin in the study of human development. Rather than seeing individual differences solely as the result of socialization, temperament research identifies basic dispositions toward affect, arousal, and attention that will be further shaped by experience in development. In this article, temperament is defined, a brief history is presented, current research is reviewed, and directions for the future are outlined. Research article Trends in Ecology & Evolution, Volume 29, Issue 7, 2014, pp. 369-371 Show abstractNavigate Down Although interest in the ecological and evolutionary implications of animal personality continues to grow, the role that personality plays in speciation has received only modest attention. Here we explore links between personality and speciation, and offer a framework for addressing some of this field's most interesting questions. Research article Psychoneuroendocrinology, Volume 76, 2017, pp. 107-113 Show abstractNavigate Down Previous research has shown that adverse social conditions may promote a conserved transcriptional response to adversity (CTRA) involving up-regulation of proinflammatory gene expression and down-regulation of Type I interferon anti-viral genes in circulating blood cells. However, the impact of social conditions on lymphoid tissue gene regulation remains largely unexplored. This project assessed how social instability in adult male rhesus macaques (N = 10, 5 in unstable, and 5 in stable social conditions) might regulate gene expression within secondary lymphoid tissue (lymph nodes; LN). Unstable social conditions down-regulated axillary LN expression of genes involved in Type I interferon anti-viral responses. Transcript origin analyses implicated monocytes and B cells as cellular mediators of these effects, and promoter-based bioinformatics analyses indicated reduced activity of AP-1, NF-κB, IRF, and CREB transcription factors within the axillary LN microenvironment. Although the current study is limited in sample size, these results suggest that social influences on immune cell gene regulation extend beyond the circulating leukocyte pool to alter generalized transcriptome profiles in secondary lymphoid tissue, and they do so in a regulatory program that resembles the pattern of antiviral inhibition previously observed in circulating leukocytes. Research article Trends in Ecology & Evolution, Volume 30, Issue 1, 2015, pp. 50-60 Show abstractNavigate Down An exciting area in behavioural ecology focuses on understanding why animals exhibit consistent among-individual differences in behaviour (animal personalities). Animal personality has been proposed to emerge as an adaptation to individual differences in state variables, leading to the question of why individuals differ consistently in state. Recent theory emphasizes the role that positive feedbacks between state and behaviour can play in producing consistent among-individual covariance between state and behaviour, hence state-dependent personality. We review the role of feedbacks in recent models of adaptive personalities, and provide guidelines for empirical testing of model assumptions and predictions. We discuss the importance of the mediating effects of ecology on these feedbacks, and provide a roadmap for including state–behaviour feedbacks in behavioural ecology research. Research article Animal Behaviour, Volume 173, 2021, pp. 137-144 Show abstractNavigate Down Animal personality is defined as consistent individual behaviour over time and across contexts, yet most studies to date only measure behaviour within a single life stage. Up to this point, developmental perspectives in the field of animal personality have received little attention. Here, we review those empirical studies that have assessed personality across major developmental periods, including metamorphosis and/or sexual maturation. We specifically focus on life history differences between direct and indirect development to enhance our understanding of the mechanisms underlying personality development. We also discuss conceptual and methodological inconsistencies across the studies reviewed here that may impede the advancement of animal personality theory. We found that personality traits tend to be stable within life stages but typically are not consistent across critical developmental events (metamorphosis and/or sexual maturation). We conclude that assessing personality within single life stages only provides a snapshot of an individual's behavioural repertoire, while long-term consideration may offer a more complete understanding on the evolution and maintenance of animal personality. Research article Psychoneuroendocrinology, Volume 76, 2017, pp. 57-66 Show abstractNavigate Down The hippocampus is most notably known for its role in cognition and spatial memory; however it also plays an essential role in emotional behaviors and neuroendocrine responses. The current study investigated the long-term effects of neonatal hippocampal lesions (Neo-Hibo) on emotional and hypothalamic-pituitary-adrenal (HPA) axis functioning. During infancy, unlike controls, Neo-Hibo monkeys exhibited enhanced expression of emotional behaviors (e.g. freezing, anxiety-like, and self-directed behaviors) when exposed to a human intruder (HI task). Upon reaching adulthood, they exhibited reduced freezing and hostility, but increased anxiety-like and self-directed behaviors during the HI task. Neo-Hibo monkeys behaved as if they systematically over-rated the risk inherent in the HI task, which supports Gray and McNaughton’s septo-hippocampal theory of anxiety. Also, in adulthood, the increased levels of anxiety-like behaviors in Neo-Hibo monkeys were associated with a blunted cortisol response to the HI task. Examination of basal HPA axis function revealed that Neo-Hibo monkeys exhibited the typical diurnal cortisol decline throughout the day, but had lower cortisol concentrations in the morning as compared to controls. Taken together these data suggest that an intact hippocampus during development plays a larger role beyond that of inhibitory/negative feedback regulation of the HPA axis stress-activation, and may be critical for HPA axis basal functioning as well as for the stress response. The behavioral and neuroendocrine changes demonstrated in the current study are reminiscent of those seen in human or nonhuman primates with adult-onset hippocampal damage, demonstrating little functional compensation following early hippocampal damage. Research article Applied Animal Behaviour Science, Volume 149, Issues 1–4, 2013, pp. 55-62 Show abstractNavigate Down The consistency of personality assessment was addressed in this study of 12 zoological African elephants living at the San Diego Zoo Safari Park in Escondido, CA, USA during the 2010 and 2011 summer seasons. Using 480 h of observational behavior data, three personality traits were determined based on behavior events, with the most significant correlations (two-tailed rs > 0.77, P < 0.005) being playful, curious, and sociable. During both summers, the animal care staff rated all elephants across 25 adjective items. Four rating-based personality traits were then clustered based on items with the most significant correlations (one-tailed rs > 0.72, P < 0.005): playful, observant, shy and confident. All seven personality traits correlated significantly (P < 0.05) from 2010 to 2011 for each individual elephant, demonstrating temporal stability. Additionally, the coded playful trait was correlated significantly (P < 0.01) to the rated trait playful, demonstrating construct validity and cross-method consistency. These results suggest that humans have the ability to discriminate zoo elephant personalities reliably and accurately. This, therefore, suggests that rating of zoo elephant personalities by caretakers with extensive knowledge of the species’ behavioral repertoire may be a valid proxy for long-term behavioral monitoring. Personality assessments may allow animal caretakers to identify appropriate roles for certain individuals (i.e., social compatibility, operant training, and transport to another facility), aid the individualization of environmental enrichment, and provide vital predictors of coping ability (i.e., stress response/resiliency). |
