Individual Differences In Risk-taking Behavior Research Articles

The interaction between cortisol and testosterone predicts leadership within rock hyrax social groups

Group movement leadership is associated with higher risks for those in the front. Leaders are the first to explore new areas and may be exposed to predation. Individual differences in risk-taking behavior may be related to hormonal differences. In challenging circumstances, such as risk-taking leadership that may pose a cost to the leader, cortisol is secreted both to increase the likelihood of survival by restoring homeostasis, and to mediate cooperative behavior. Testosterone too has a well-established role in risk-taking behavior, and the dual-hormone hypothesis posits that the interaction of testosterone and cortisol can predict social behavior. Based on the dual-hormone hypothesis, we investigated here whether the interaction between testosterone and cortisol can predict risk-taking leadership behavior in wild rock hyraxes (Procavia capensis). We used proximity loggers, observations, and playback trials to characterize hyrax leaders in three different leadership contexts that varied in their risk levels. In support of the dual-hormone hypothesis, we found that cortisol and testosterone interactions predict leadership that involves risk. Across different circumstances that involved low or high levels of risk, testosterone was positively related to leadership, but only in individuals (both males and females) with low levels of cortisol. We also found an interaction between these hormone levels and age at the low-risk scenarios. We suggest that the close social interactions and affiliative behavior among hyrax females within small egalitarian groups may make female leadership less risky, and therefore less stressful, and allow female leaders to influence group activities.

Bold Behavior Is Associated with Genes That Regulate Energy Use but Does Not Covary with Body Condition in Food-Restricted Snails.

AbstractTheoretical models about the relationship between food restriction and individual differences in risk-taking behavior (i.e., boldness) have led to conflicting predictions: some models predict that food restriction increases boldness, while other models predict that food restriction decreases boldness. This discrepancy may be partially attributable to an underappreciation for animals' complex physiological responses to food restriction. To understand the proximate mechanisms mediating state-dependent boldness, we used freshwater snails (Helisoma trivolvis) to examine the relationships among food availability, body condition, boldness (latency to reemerge from shell and exploration), and mRNA expression of three genes (adenosine monophosphate-activated protein kinase [AMPK], molluscan insulin-like peptide [MIP], and serotonin receptor [5-HT]) involved in maintaining energy homeostasis during periods of moderate food restriction. Latency to reemerge and exploratory behavior decreased over time, but fed snails were bolder than fasted snails, suggesting that food restriction reduces bold behavior. Although food restriction decreased body condition, there was not a relationship between body condition and latency to reemerge from shell. However, expression of MIP was positively correlated with latency to reemerge from shell. Furthermore, AMPK was positively correlated with MIP and negatively correlated with body condition and 5-HT. Therefore, individual differences in physiological responses to food restriction, not overall body condition per se, appear to be more closely associated with state-dependent bold behavior. Finally, snails that experienced a novel assay environment returned to their initial "shy" behavior, suggesting that habituation to the assay environment may contribute to snails expressing bolder behavior over time.

Predator experience homogenizes consistent individual differences in predator avoidance

In the presence of predators, many prey species exhibit immediate behavioral responses like the avoidance of risky areas, which imposes opportunity costs, for instance, in the form of reduced foraging. Thus, prey species should be able to discriminate between different predator types and adjust their response to the imminent predation risk. In our current study, we evaluated the relative importance of innate versus learned components of predator recognition and avoidance in the guppy (Poecilia reticulata). We used a feral guppy population occurring in Germany and compared avoidance reactions of each focal individual towards both coevolved piscine predators from their original distribution range and novel, presently co-occurring predator species. Wild-caught, predator-experienced as well as laboratory-reared, predator-naive individuals showed strong avoidance responses towards all predator animations. Avoidance was stronger in small-bodied than in large-bodied individuals in both cohorts; however, this effect was significant only in predator-naive fish. Moreover, wild-caught individuals showed a significantly higher within-individual variance (across the six predator species) along with a lower among-individual variance in predator avoidance, which resulted in a lower behavioral repeatability in this cohort. Our results suggest that consistent individual differences in risk-taking behavior (also referred to as the personality trait ‘boldness’) are modified by predator exposure and learning about predators.

Evaluation of boldness assays and associated behavioral measures in a social parrot, monk parakeet (Myiopsitta monachus)

Boldness reflects consistent individual differences in risk-taking behavior across various contexts. However, evaluating this basic assumption has largely been neglected in birds. In a captive monk parakeet population (Myiopsitta monachus; ), we undertook an analysis of 7 measures across 3 commonly used boldness assays (i.e., novel object, emergence, and predator-exposure tests). Using principal component analysis, we derived 3 components (PCs). PC-2 loaded strongly with measures from emergence and predator-exposure tests; we interpreted it as the closest approximation of boldness. PC-1 and PC-3 described different aspects of feeding such as foraging activity and rate, respectively. Finally, we assessed the predictive power of each measure that loaded significantly on the boldness axis. We found that no single metric explained even %55 of the variation in PC-2, nor could more than %50 individuals at the extremes of the spectrum be predicted. Our results demonstrate the utility of an inclusive approach in personality research.

Nucleus Accumbens Neurons Track Behavioral Preferences and Reward Outcomes During Risky Decision Making

To make appropriate decisions, organisms must evaluate the risks and benefits of action selection. The nucleus accumbens (NAc) has been shown to be critical for this processing and is necessary for appropriate risk-based decision-making behavior. However, it is not clear how NAc neurons encode this information to promote appropriate behavioral responding. Here, rats (n = 17) were trained to perform a risky decision-making task in which discrete visual cues predicted the availability to respond for a smaller certain (safer) or larger uncertain (riskier) reward. Electrophysiological recordings were made in the NAc core and shell to evaluate neural activity during task performance. At test, animals exhibited individual differences in risk-taking behavior; some displayed a preference for the risky option, some the safe option, and some did not have a preference. Electrophysiological analysis indicated that NAc neurons differentially encoded information related to risk versus safe outcomes. Further, during free choice trials, neural activity during reward-predictive cues reflected individual behavioral preferences. In addition, neural encoding of reward outcomes was correlated with risk-taking behavior, with safe-preferring and risk-preferring rats showing differential activity in the NAc core and shell during reward omissions. Consistent with previously demonstrated alterations in prospective reward value with effort and delay, NAc neurons encode information during reward-predictive cues and outcomes in a risk task that tracked the rats' preferred responses. This processing appears to contribute to subjective encoding of anticipated outcomes and thus may function to bias future risk-based decisions.

Predicting Risk-Taking Behavior from Prefrontal Resting-State Activity and Personality

Risk-taking is subject to considerable individual differences. In the current study, we tested whether resting-state activity in the prefrontal cortex and trait sensitivity to reward and punishment can help predict risk-taking behavior. Prefrontal activity at rest was assessed in seventy healthy volunteers using electroencephalography, and compared to their choice behavior on an economic risk-taking task. The Behavioral Inhibition System/Behavioral Activation System scale was used to measure participants’ trait sensitivity to reward and punishment. Our results confirmed both prefrontal resting-state activity and personality traits as sources of individual differences in risk-taking behavior. Right-left asymmetry in prefrontal activity and scores on the Behavioral Inhibition System scale, reflecting trait sensitivity to punishment, were correlated with the level of risk-taking on the task. We further discovered that scores on the Behavioral Inhibition System scale modulated the relationship between asymmetry in prefrontal resting-state activity and risk-taking. The results of this study demonstrate that heterogeneity in risk-taking behavior can be traced back to differences in the basic physiology of decision-makers’ brains, and suggest that baseline prefrontal activity and personality traits might interplay in guiding risk-taking behavior.

Risky business: Executive function, personality, and reckless behavior during adolescence and emerging adulthood.

Adolescence is a risky business. Despite outstanding physical health, the risk of injury or death during adolescence is 2-3 times that of childhood. The primary cause of this increase in morbidity and mortality is heightened risky behavior including drinking, driving, drug-taking, smoking, and unprotected sex. Why is it that some adolescents take big risks, while others do not? One potential source of individual differences in risk-taking behavior may lie in individual differences in executive function including judgment, impulse control, self-monitoring, and planning. Researchers have hypothesized that limited brain system integration and efficiency, particularly in the prefrontal cortex and related structures, may be involved in the range and degree of risky behavior commonly exhibited by teens. In the present study, we examined the relation between risky behavior, personality factors, and performance on neuropsychological tests of executive function. The community sample of 136 adolescents aged 13- to 17-years-old and 57 emerging adults aged 18- to 22-years-old exhibited marked individual differences in risk-taking behavior; participants' scores on a alcohol, smoking, drugs, sex, driving, and antisocial behavior questionnaire ranged from 0 to near the maximum value possible. We found that risky personality and performance on the neuropsychological tests were both significant predictors of real-world risk-taking. These data have important implications for current public policies involving adolescents and emerging adults.

Relationship Between Adolescent Risk Preferences on a Laboratory Task and Behavioral Measures of Risk-Taking

The goal of the study was to assess individual differences among adolescents regarding risk-taking behavior in the laboratory. The second aim was to evaluate whether the laboratory-based risk-taking behavior is associated with other behavioral and psychological measures associated with risk-taking behavior. A total of 82 adolescents with no personal history of psychiatric disorder completed a computerized decision-making task, the Wheel of Fortune. On the basis of the choices made between clearly defined probabilities and real monetary outcomes, this task assesses risk preferences when participants are confronted with potential rewards and losses. The participants also completed a variety of behavioral and psychological measures associated with risk-taking behavior. Performance on the task varied on the basis of probability and anticipated outcomes. In the winning sub-task, participants selected low-probability-high-magnitude reward (high-risk choice) less frequently than high-probability-low-magnitude reward (low-risk choice). In the losing sub-task, participants selected low-probability-high-magnitude loss more often than high-probability-low-magnitude loss. On average, the selection of probabilistic rewards was optimal and similar to performance in adults. There were, however, individual differences in performance, and one-third of the adolescents made high-risk choice more frequently than low-risk choice while selecting a reward. After controlling for sociodemographic and psychological variables, high-risk choice on the winning task predicted "real-world" risk-taking behavior and substance-related problems. These findings highlight individual differences in risk-taking behavior. Regarding validity of the Wheel of Fortune task, the preliminary data suggest that it might be a valuable laboratory tool for studying behavioral and neurobiological processes associated with risk-taking behavior in adolescents.

Zebrafish (Danio rerio) exhibit individual differences in risk-taking behavior during predator inspection

Risk-taking behavior associated with predator inspection has been described in a number of fish species. As a first step in parsing out the contribution of genes and environment to risk-taking behavior, the predator inspection behavior of zebrafish was examined. Predator inspection behavior of seventy males was measured once a day for five consecutive days and their mean daily inspection score — a measure of risk-taking tendencies — was recorded. Zebrafish did not habituate to the presence of a predator and significant individual differences in risk-taking behavior were uncovered.

Independent coding of reward magnitude and valence in the human brain.

Previous research has shown that two components of the event-related brain potential, the P300 and feedback negativity, are sensitive to information about rewards and penalties. The present study investigated the properties of these components in a simple gambling game that required participants to choose between cards that were unpredictably associated with monetary gains and losses of variable magnitude. The aim was to determine the sensitivity of each component to two critical features of reward stimuli: magnitude (small or large) and valence (win or loss). A double dissociation was observed, with the P300 sensitive to reward magnitude but insensitive to reward valence and the feedback negativity showing the opposite pattern, suggesting that these two fundamental features of rewarding stimuli are evaluated rapidly and separately in the human brain. Subsequent analyses provided additional evidence of functional dissociations between the feedback negativity and P300. First, the P300 (but not the feedback negativity) showed sensitivity to the reward value of alternative, nonselected stimuli. Second, individual differences in the amplitude of the feedback negativity correlated with individual differences in risk-taking behavior observed after monetary losses, whereas individual differences in P300 amplitude were related to behavioral adjustments observed in response to alternative, unchosen outcomes.