Individual Differences In Behavior Research Articles

Individual Responses of Captive Amazon Parrots to Routine Handling Can Reflect Their Temperament

Individual responses to physical restraint and temperament have been assessed in birds of several species; however, there is a paucity of research which investigates both aspects, especially in captive parrots. This lack of studies raises doubts about which temperament traits, if any, are evidenced during handling and if the intensity of responses to restraint is affected by behavioral training programs, a common practice used in ex situ conservation programs. To understand more about the subject, this study aimed to identify the main temperament dimensions of parrots and investigate their relationship with response to physical restraint for blood collection. A secondary aim was to evaluate whether parrots exhibited higher responsiveness to physical restraint after training to improve flight capacity and increase aversion to humans. The main dimensions identified were activity, neophilia, vigilance, and fearfulness. The more fearful parrots in temperament evaluations were more responsive to physical restraint, showing more vocalizations and struggle attempts than the less fearful ones. After training, the parrots showed higher responsiveness to physical restraint. We suggest that physical restraint for routine handling, such as blood collection, could be a feasible option for centers of rehabilitation to use to obtain data on individual behavioral differences in fear responses.

Task fMRI paradigms may capture more behaviorally relevant information than resting-state functional connectivity

Characterizing the optimal fMRI paradigms for detecting behaviorally relevant functional connectivity (FC) patterns is a critical step to furthering our knowledge of the neural basis of behavior. Previous studies suggested that FC patterns derived from task fMRI paradigms, which we refer to as task-based FC, are better correlated with individual differences in behavior than resting-state FC, but the consistency and generalizability of this advantage across task conditions was not fully explored. Using data from resting-state fMRI and three fMRI tasks from the Adolescent Brain Cognitive Development Study ® (ABCD), we tested whether the observed improvement in behavioral prediction power of task-based FC can be attributed to changes in brain activity induced by the task design. We decomposed the task fMRI time course of each task into the task model fit (the fitted time course of the task condition regressors from the single-subject general linear model) and the task model residuals, calculated their respective FC, and compared the behavioral prediction performance of these FC estimates to resting-state FC and the original task-based FC. The FC of the task model fit was better than the FC of the task model residual and resting-state FC at predicting a measure of general cognitive ability or two measures of performance on the fMRI tasks. The superior behavioral prediction performance of the FC of the task model fit was content-specific insofar as it was only observed for fMRI tasks that probed similar cognitive constructs to the predicted behavior of interest. To our surprise, the task model parameters, the beta estimates of the task condition regressors, were equally if not more predictive of behavioral differences than all FC measures. These results showed that the observed improvement of behavioral prediction afforded by task-based FC was largely driven by the FC patterns associated with the task design. Together with previous studies, our findings highlighted the importance of task design in eliciting behaviorally meaningful brain activation and FC patterns.

Temperament traits and glucocorticoid metabolites in tropical screech owl (Megascops choliba)

Animals constantly respond to stimuli from their surroundings, showing individual behavioral and endocrine differences upon perceived challenging and/or threatening stimuli. The temperament of 13 captive tropical screech owls (Megascops choliba) was defined by performing three challenge tests (novel space, taxidermist predator and trapping) to identify inter-individual differences and their possible relationship with the production of glucocorticoid metabolites (GCM). Feces samples of each bird were taken pre-and-post predator challenge to quantify GCM concentration by means of enzymatic immunoassay (EIA). The intensity of 13 adjectives selected to describe the owls' temperament was determined by three judges during behavioral testing. Only 3 adjectives (passive, vulnerable, and attentive) that showed strong inter-test and intra-individual correlation coefficients were considered. These adjectives were later grouped in a single dimension named “shyness”, enabling establishment of individual scores. The temperament of the owls showed correlation to post-predator challenge GCM levels (ρ = 0.79; p < 0.001). However, no significant differences were found in GCM levels before and after predator challenge. Our results both confirm that nocturnal behavior raptorial birds show positive relation between shy temper and adrenal response, and offer the non-invasive herein implemented methods for establishment of new hypotheses that will assess welfare of species kept under human care.

Association of personality traits with maintenance and social behaviour of rams (Ovis aries)

Animal personality is defined as individual differences in behaviour that are consistent over time and in different contexts. Aspects of personality (personality traits) have been identified in previous studies on farm animals indicating that they may affect the individuals’ behaviour, dominance rank, coping and cognitive ability and physiology. The aim of the present study was to identify whether rams (Ovis aries) reared under an intensive farming system, present personality traits and if these traits are associated with the behaviour of individuals under different contexts, to gain a better understanding on sheep personality and the consistency of behaviour within individuals. Adult rams (N = 13) reared under an intensive system were observed during three different periods (A, B, C). At period A rams formed one stable group of eight individuals. Period B started when five rams entered the group simultaneously and period C when rams formed one stable group of 13 individuals. Scan sampling was used to record if and with whom each individual was in proximity. All social behaviours between individuals were collected ad libitum and maintenance behaviours were scored using focal sampling. The study demonstrated two personality traits, namely Dynamic and Receptive, as the two aspects of rams’ personality (KMO = 0.667; p < 0.01). Dynamic behaviour was correlated with frequent vocalizations (rs = 0.586, p < 0.05) while receptive behaviour was correlated with increased time lying (rs = 0.593, p < 0.05). Furthermore, an association was noted between individuals’ personality scores and social behaviour (p < 0.05), indicating that dynamic individuals appeared to perform more agonistic behaviour (p < 0.05) and receive more submissive (p < 0.01), within the examined periods.

Active visual search in naturalistic environments reflects individual differences in classic visual search performance

Visual search is a ubiquitous activity in real-world environments. Yet, traditionally, visual search is investigated in tightly controlled paradigms, where head-restricted participants locate a minimalistic target in a cluttered array that is presented on a computer screen. Do traditional visual search tasks predict performance in naturalistic settings, where participants actively explore complex, real-world scenes? Here, we leverage advances in virtual reality technology to test the degree to which classic and naturalistic search are limited by a common factor, set size, and the degree to which individual differences in classic search behavior predict naturalistic search behavior in a large sample of individuals (N = 75). In a naturalistic search task, participants looked for an object within their environment via a combination of head-turns and eye-movements using a head-mounted display. Then, in a classic search task, participants searched for a target within a simple array of colored letters using only eye-movements. In each task, we found that participants’ search performance was impacted by increases in set size—the number of items in the visual display. Critically, we observed that participants’ efficiency in classic search tasks—the degree to which set size slowed performance—indeed predicted efficiency in real-world scenes. These results demonstrate that classic, computer-based visual search tasks are excellent models of active, real-world search behavior.

Categorizing the behavior and values of detached housing residents related to obtaining warmth

AbstractThe categoraization employed for Kyoto residents' consciousness, values, and physical constitution described in the previous report was also applied to Hiroshima and Aichi, and the validity of the categoraization was confirmed. The findings of this study can be summarized as follows: (1) The questions on the residents' consciousness, values, and physical constitution were highly independent, and the first principal component, “the importance of values, such as environmental protection, traditions, and seasonality,” and the second component, “tolerance/patience with cold weather,” were found to be applicable to Hiroshima and Aichi, as well as to Kyoto. (2) The two principal components were used to categorize residents into four groups in each of the study areas, and the characteristics of each group were reviewed. Trends in the three areas were similar, but there were also trends unique to Hiroshima and Aichi, where consciousness and values prioritizing the environment and nature conservation were observed. (3) We consider that observing environmental regulation behavior with a focus on the consciousness, values, and physical constitution of residents may provide clues to understanding the diversity of living styles. This leads to the identification of individual differences in adaptive behavior toward the thermal environment.

Compete with Me? The Impact of Online Gamified Competition on Exercise Behavior

Online gamified competition utilizes competition as a core gamification design element with affordances from wearables and mobile applications to track competitive activities and visualize information in an integrated way to shape users’ exercise behaviors. However, a clear understanding of how online gamified competition cultivates exercise behaviors in different types of individuals is still lacking. We take into account the individual differences in exercise behaviors and categorize exercisers into three groups (active, moderate, and inactive) based on an adapted recency, frequency, and monetary value framework using key exercise behavior metrics. Theorizing online gamified competition as a means of social and temporal self-comparison, we examine the effect of performance feedback from two distinct modes of comparison (performance rankings and performance gap), and participants’ relationships with their social comparison referents (i.e., rivalry intensity), on the exercise behaviors of different exerciser groups. Our results reveal that online gamified competition has differential effects on exercise behaviors across different exerciser groups. Specifically, we find that positive performance improvements are more motivational for active and moderate exercisers, while performance deterioration relative to historical exercise performance level is more discouraging for inactive exercisers. Performance rankings exhibit a more salient effect for moderate and inactive exercisers, and rivalry intensity has a stronger positive effect on active exercisers’ exercise behavior. The strengthening effect of awareness affordances in mobile fitness apps is more notable with regard to the impact of rivalry intensity on moderate and inactive exercisers. We derive theoretical and practical implications of gamified information systems that use competition as a core design element for shaping the exercise behavior of individuals in different exerciser groups.

Trait Covariances in Eastern Box Turtles Do Not Support Pleiotropic Effects of the Melanocortin System on Color, Behavior, and Stress Physiology

Endocrine systems and individual behavioral differences (temperament) are often linked in animals. In particular, glucocorticoids (corticosterone [CORT]) have been implicated in animal coping styles, or syndromes of integrated temperamental and neuroendocrine variation. Typically, organisms with lower stress-induced elevations of CORT tend to exhibit more proactive behavior. Melanin-based coloration has been further linked to CORT physiology and temperament, with more melanistic individuals typically exhibiting more proactive coping styles. The melanocortin hypothesis proposes that variation in the melanocortin system could drive the repeated covariation in coloration, coping style, and CORT levels. We evaluated the relationships among the CORT stress response, boldness (i.e., responsiveness to risk), and melanization of the shell in Eastern Box Turtles (Terrapene carolina carolina), predicting that turtles with bolder temperaments would exhibit lower stress-induced CORT levels and possess darker shells. We also expected stress-induced CORT levels to be lower at cooler body temperatures. Our results generally failed to support the melanocortin hypothesis. We found no significant correlations among behavior, CORT, and melanization, and correlations that approached significance were weak. Moreover, the near significant relationship between CORT levels and boldness is in the opposite direction predicted. We also found that temperature had a strong positive effect on CORT levels, and there were population differences in plastron melanization and boldness.

Neurophysiological consequences of synapse loss in progressive supranuclear palsy.

Synaptic loss occurs early in many neurodegenerative diseases and contributes to cognitive impairment even in the absence of gross atrophy. Currently, for human disease there are few formal models to explain how cortical networks underlying cognition are affected by synaptic loss. We advocate that biophysical models of neurophysiology offer both a bridge from preclinical to clinical models of pathology and quantitative assays for experimental medicine. Such biophysical models can also disclose hidden neuronal dynamics generating neurophysiological observations such as EEG and magnetoencephalography. Here, we augment a biophysically informed mesoscale model of human cortical function by inclusion of synaptic density estimates as captured by 11C-UCB-J PET, and provide insights into how regional synapse loss affects neurophysiology. We use the primary tauopathy of progressive supranuclear palsy (Richardson's syndrome) as an exemplar condition, with high clinicopathological correlations. Progressive supranuclear palsy causes a marked change in cortical neurophysiology in the presence of mild cortical atrophy and is associated with a decline in cognitive functions associated with the frontal lobe. Using parametric empirical Bayesian inversion of a conductance-based canonical microcircuit model of magnetoencephalography data, we show that the inclusion of regional synaptic density-as a subject-specific prior on laminar-specific neuronal populations-markedly increases model evidence. Specifically, model comparison suggests that a reduction in synaptic density in inferior frontal cortex affects superficial and granular layer glutamatergic excitation. This predicted individual differences in behaviour, demonstrating the link between synaptic loss, neurophysiology and cognitive deficits. The method we demonstrate is not restricted to progressive supranuclear palsy or the effects of synaptic loss: such pathology-enriched dynamic causal models can be used to assess the mechanisms of other neurological disorders, with diverse non-invasive measures of pathology, and is suitable to test the effects of experimental pharmacology.

Heightened cocaine-seeking in male rats associates with a distinct transcriptomic profile in the medial prefrontal cortex.

Drug overdose deaths involving cocaine have skyrocketed, an outcome attributable in part to the lack of FDA-approved medications for the treatment of cocaine use disorder (CUD), highlighting the need to identify new pharmacotherapeutic targets. Vulnerability to cocaine-associated environmental contexts and stimuli serves as a risk factor for relapse in CUD recovery, with individual differences evident in the motivational aspects of these cues. The medial prefrontal cortex (mPFC) provides top-down control of striatal circuitry to regulate the incentive-motivational properties of cocaine-associated stimuli. Clinical and preclinical studies have identified genetic variations that impact the degree of executive restraint over drug-motivated behaviors, and we designed the present study to employ next-generation sequencing to identify specific genes associated with heightened cue-evoked cocaine-seeking in the mPFC of male, outbred rats. Rats were trained to stably self-administer cocaine, and baseline cue-reinforced cocaine-seeking was established. Rats were phenotyped as either high cue (HC) or low cue (LC) responders based upon lever pressing for previously associated cocaine cues and allowed 10 days of abstinence in their home cages prior to mPFC collection for RNA-sequencing. The expression of 309 genes in the mPFC was significantly different in HC vs. LC rats. Functional gene enrichment analyses identified ten biological processes that were overrepresented in the mPFC of HC vs. LC rats. The present study identifies distinctions in mPFC mRNA transcripts that characterizes individual differences in relapse-like behavior and provides prioritized candidates for future pharmacotherapeutics aimed to help maintain abstinence in CUD. In particular the Htr2c gene, which encodes the serotonin 5-HT2C receptor (5-HT2CR), is expressed to a lower extent in HC rats, relative to LC rats. These findings build on a plethora of previous studies that also point to the 5-HT2CR as an attractive target for the treatment of CUD.

Injected serotonin decreases foraging aggression in black widow spiders (Latrodectus hesperus), but dopamine has no effect

A fundamental goal of animal behavior research is to discover the proximate mechanisms driving individual behavioral differences. Biogenic amines are known to mediate various aspects of behavior across many species, including aggression, one of the most commonly measured behavioral traits in animals. Arthropods provide an excellent system to manipulate biogenic amines and quantify subsequent behavioral changes. Here, we investigated the role of dopamine (DA) and serotonin (5-HT) on foraging aggression in western black widow spiders (Latrodectus hesperus), as measured by the number of attacks on a simulated prey animal in the web. We injected spiders with DA or 5-HT and then quantified subsequent changes in behavior over 48 h. Based on previous work on insects and spiders, we hypothesized that increasing DA levels would increase aggression, while increasing 5-HT would decrease aggression. We found that injection of 5-HT did decrease black widow foraging aggression, but DA had no effect. This could indicate that the relationship between DA and aggression is complex, or that DA may not play as important a role in driving aggressive behavior as previously thought, at least in black widow spiders. Aggressive behavior is likely also influenced by other factors, such as inter-individual differences in genetics, metabolic rates, environment, and other neurohormonal controls.

Using observer similarity matrices to understand individual differences in gaze behaviour towards objects in complex scenes

Using observer similarity matrices to understand individual differences in gaze behaviour towards objects in complex scenes

Personality aspects and proenvironmental attitudes.

Climate change is a serious threat. Personality psychologists can help address this threat by understanding what kind of people tend to endorse proenvironmental attitudes and engage in sustainable behavior. Previous research supports reliable associations between proenvironmental attitudes and personality traits. However, this research has generally aggregated different kinds of attitudes into a single composite and has focused on the domain level of personality traits. This study explored how 10 lower-order aspects of the Big Five personality traits were related to eight different proenvironmental attitudes in three convenience samples from the United States (N=1234; 1000) and the United Kingdom (N=538). All five trait domains were related to at least one proenvironmental attitude across all three samples. Seven of eight proenvironmental attitudes could be predicted by one or more traits in all three samples. We also found evidence that the Openness aspect of Openness to Experience was a more consistent predictor of proenvironmental attitudes than the Intellect aspect. In contrast, there was little benefit in distinguishing between the aspects of other trait domains. We did not find evidence that age or political orientation moderated the associations between proenvironmental attitudes and personality. Results point to the need for more fine-grained research on individual differences in proenvironmental attitudes and behavior.

At First Glance: The Effect of Spatial Attentional Bias and Individual Differences in First-Fixation Behavior During Visual Search

At First Glance: The Effect of Spatial Attentional Bias and Individual Differences in First-Fixation Behavior During Visual Search

Responses to environmental enrichment are associated with personality characteristics in chestnut-bellied seed finches (Sporophila angolensis)

Environmental enrichment (EE) is used to promote natural behaviours in captive animals and may hold promise as a form of pre-release training, a strategy for improving coping skills of translocated birds. We investigated the use of EE to enhance foraging and vigilance behaviours of captive Sporophila angolensis, which may be related to post-release survival. We also evaluated whether consistent individual behavioural differences affected birds’ responses to EE. We submitted 19 captive seed-finches to three short-term challenges: tonic immobility (TI), new environment (NE) and new object (NO) tests. TI behaviour is related to fear/escape response to potential predators and novelty tests (NE and NO) assess neophobia, which are ecologically relevant personality traits influencing the shyness-boldness continuum. We noted a pronounced variability among the individuals’ personality traits, both in their fear and escape-related responses in the TI test and along shy/bold z-scores in NE and NO tests. During a period of enrichment, birds spent more time foraging and less time in vigilance states compared with both control phases. Personality traits of the birds affected their responses to enrichment with bolder birds spending more time foraging. The EE-related decrease in vigilance was independent of the birds’ personality traits. Our findings highlight interactions between personality and rearing environment that may impact post-release outcomes for translocated animals.

A Century of Behavioral Genetics at the University of Minnesota.

The University of Minnesota has played an important role in the resurgence and eventual mainstreaming of human behavioral genetics in psychology and psychiatry. We describe this history in the context of three major movements in behavioral genetics: (1) radical eugenics in the early 20th century, (2) resurgence of human behavioral genetics in the 1960s, largely using twin and adoption designs to obtain more precise estimates of genetic and environmental influences on individual differences in behavior; and (3) use of measured genotypes to understand behavior. University of Minnesota scientists made significant contributions especially in (2) and (3) in the domains of cognitive ability, drug abuse and mental health, and endophenotypes. These contributions are illustrated through a historical perspective of major figures and events in behavioral genetics.

Sex-Specific Effects of Blood Serotonin on Reproductive Effort in a Small Passerine.

AbstractLaboratory animal models have shown that blood serotonin levels reflect consistent individual differences in behavioral decision-making and maternal behavior. Serotonin could also help to understand intraspecific variation in reproductive strategies, although the mechanisms are poorly understood. In this study, the relationships of plasma serotonin with breeding parameters and parental behavior were examined in wild great tits (Parus major). Females who laid eggs earlier had higher levels of serotonin in the second half of the nestling period, while no significant relationship of serotonin with clutch size, brood size, and body size was detected. In males, serotonin levels were negatively related to clutch size and brood size and positively related to body size. The association of serotonin with provisioning behavior was sex specific, and acute fear stress induced by a predator presentation did not change this relationship. Food provisioning was positively related to size-corrected serotonin levels in females and negatively related to size-corrected serotonin levels in males. These results suggest that peripheral serotonin is a sensitive marker of parental behavior and reproductive effort in wild birds, while the mechanisms linking this neurotransmitter to reproduction are probably mediated by interplay between the serotonergic system, sex hormones, and other neurotransmitters.

How do we characterize temperament? Broad testing of temperament across time and contexts in low-variable conditions

In many species, individual animals often maintain relatively consistent individual differences in behaviour, indicative of temperament or personality. These stable individual differences are important for life history, survival and health consequences, and the field has seen exponential growth in temperament (e.g. boldness, exploration, sociability, aggression and activity) research. Quantification of animal temperament can be difficult because it requires (1) repeated behavioural measures from the same individual (to gauge within-individual consistency across time and contexts) and (2) identification of the most appropriate behaviour(s) to characterize temperament. In the current study, we took an atheoretical approach and conducted repeat, diverse behavioural tests in a low-variable environment to determine behaviours that were individually consistent over time and across conditions. To control environmental effects on behaviour, we conducted this work with individually housed outbred male Sprague–Dawley rats in a laboratory. To determine individual consistency, we measured each rat's behavioural response to five different arenas (i.e. different contexts) and repeated the five tests at three time points. To identify potential composite, multibehaviour estimates of temperament, we used factor analyses to determine behaviours that covaried on each test arena, and calculated factor scores. To determine individual consistency of behaviours and factor scores across time and contexts, we used reliability and correlation analyses. Several behaviours consistently covaried on each test, and with a few notable exceptions, the resulting factors tended to align with five commonly studied temperament categories. Certain behaviours/factors were more consistent across time and contexts than others; distance travelled/activity were highly consistent, as were sociality- and boldness-related behaviours, whereas aggression and exploration were less consistent. We did not find strong evidence that multibehaviour estimates of temperament (factor scores) were more consistent over time or across conditions than single-behaviour metrics. Where possible, similar atheoretical approaches to cross-time and cross-context behaviour testing will be beneficial for initial temperament characterization.

Individual differences in looking at persons in scenes.

Individuals freely viewing complex scenes vary in their fixation behavior. The most prominent and reliable dimension of such individual differences is the tendency to fixate faces. However, much less is known about how observers distribute fixations across other body parts of persons in scenes and how individuals may vary in this regard. Here, we aimed to close this gap. We expanded a popular annotated stimulus set (Xu, Jiang, Wang, Kankanhalli, & Zhao, 2014) with 6,365 hand-delineated pixel masks for the body parts of 1,136 persons embedded in 700 complex scenes, which we publish with this article (https://osf.io/ynujz/). This resource allowed us to analyze the person-directed fixations of 103 participants freely viewing these scenes. We found large and reliable individual differences in the distribution of fixations across person features. Individual fixation tendencies formed two anticorrelated clusters, one for the eyes, head, and the inner face and one for body features (torsi, arms, legs, and hands). Interestingly, the tendency to fixate mouths was independent of the face cluster. Finally, our results show that observers who tend to avoid person fixations in general, particularly do so for the face region. These findings underscore the role of individual differences in fixation behavior and reveal underlying dimensions. They are further in line with a recently proposed push-pull relationship between cortical tuning for faces and bodies. They may also aid the comparison of special populations to general variation.

Exposure to whale watching vessels affects dive ascents and resting behavior in sperm whales

Disturbance from whale watching can induce a wide range of behavioral responses in cetaceans, some of which can affect their energetic balance and, ultimately, their long-term fitness. However, assessing disturbance effects on deep-diving cetaceans remains challenging, as the majority of their activities occurs underwater and are difficult to monitor from surface observations. To surpass this limitation, we attached high-resolution multi-sensor tags (DTAGs) on 24 sperm whales (Physeter macrocephalus) off the Azores, an area of intense whale watching, to evaluate changes in movement and acoustic parameters related to foraging effort and dives, locomotion effort, and non-foraging behavior. These parameters were compared between periods of exposure and non-exposure to whale watching vessels, using linear mixed-effect models to assess the presence of short-term effects, accounting for individual differences in behavior. We found no significant changes in foraging effort (number of buzzes, bottom phase depth, proportion of search and foraging phases) and overall dive behavior (dive duration, proportion of dive phases, and descending or ascending pitch) between non-exposure and exposure periods. In contrast, variation in body pitch during non-foraging periods increased during exposure but not variation in body roll. Taken together, these results suggest increased movements during resting activity, which may carry energetic costs to whales and impact their health. Vertical velocity during ascents was also significantly higher in response to vessel exposure, suggesting that sperm whales increased the frequency of fluke strokes, which was consistent with a higher Overall Dynamic Body Acceleration (ODBA) during ascents, incurring in higher energy expenditure. If the detected changes are repeated across multiple exposures, they might affect the individual’s energetic budget, and consequently their fitness. Our study contributes to a better understanding of the short-term behavioral responses of sperm whales to whale watching vessels and highlights the need for further studies examining the potential consequences from repeated disturbance to individuals.