Sex differences in the predictability of risk-taking behavior

Recent research has found that individuals often vary in how consistently they express their behavior over time (i.e., behavioral predictability) and suggested that these individual differences may be heritable. However, little is known about the intrinsic factors that drive variation in the predictability of behavior. Indeed, whether variation in behavioral predictability is sex-specific is not clear. This is important, as behavioral predictability has been associated with vulnerability to predation, suggesting that the predictability of behavioral traits may have key fitness implications. We investigated whether male and female eastern mosquitofish (Gambusia holbrooki) differed in the predictability of their risk-taking behavior. Specifically, over a total of 954 behavioral trials, we repeatedly measured risk-taking behavior with three commonly used assays-refuge-use, thigmotaxis, and foraging latency. We predicted that there would be consistent sex differences in both mean-level risk-taking behavior and behavioral predictability across the assays. We found that risk-taking behavior was repeatable within each assay, and that some individuals were consistently bolder than others across all three assays. There were also consistent sex differences in mean-level risk-taking behavior, with males being bolder across all three assays compared to females. In contrast, both the magnitude and direction of sex differences in behavioral predictability were assay-specific. Taken together, these results highlight that behavioral predictability may be independent from underlying mean-level behavioral traits and suggest that males and females may differentially adjust the consistency of their risk-taking behavior in response to subtle changes in environmental conditions.

Mathematical modeling of risk-taking in bipolar disorder: Evidence of reduced behavioral consistency, with altered loss aversion specific to those with history of substance use disorder

Bipolar disorder (BD) is associated with excessive pleasure-seeking risk-taking behaviors that often characterize its clinical presentation. However, the mechanisms of risk-taking behavior are not well-understood in BD. Recent data suggest prior substance use disorder (SUD) in BD may represent certain trait-level vulnerabilities for risky behavior. This study examined the mechanisms of risk-taking and the role of SUD in BD via mathematical modeling of behavior on the Balloon Analogue Risk Task (BART). Three groups-18 euthymic BD with prior SUD (BD+), 15 euthymic BD without prior SUD (BD-), and 33 healthy comparisons (HC)-completed the BART. We modeled behavior using 4 competing hierarchical Bayesian models, and model comparison results favored the Exponential-Weight Mean-Variance (EWMV) model, which encompasses and delineates five cognitive components of risk-taking: prior belief, learning rate, risk preference, loss aversion, and behavioral consistency. Both BD groups, regardless of SUD history, showed lower behavioral consistency than HC. BD+ exhibited more pessimistic prior beliefs (relative to BD- and HC) and reduced loss aversion (relative to HC) during risk-taking on the BART. Traditional measures of risk-taking on the BART (adjusted pumps, total points, total pops) detected no group differences. These findings suggest that reduced behavioral consistency is a crucial feature of risky decision-making in BD and that SUD history in BD may signal additional trait vulnerabilities for risky behavior even when mood symptoms and substance use are in remission. This study also underscores the value of using mathematical modeling to understand behavior in research on complex disorders like BD.

Personality coherence as a personality dynamics-related concept

Extant theoretical models of personality coherence/incoherence do not sufficiently address the challenge of explaining personality coherence dynamics and the role of psychological mechanisms, including temperament and attention. To overcome these limitations, the Complex-System Approach to Personality (C-SAP) postulates that personality coherence is a within-person structure that arises from the functional consistency/inconsistency between personality traits/types, underlain by specific attentional and temperament mechanisms that have integrative and regulatory potential. The dominant (reactive, regulative) function of stimulation processing in temperament types is the foundation for assessing personality coherence. This paper presents a revised, fine-grained model of personality coherence - originally arising from the C-SAP - that is enriched by a focus on personality coherence dynamics in relation to behavioral consistency. The methodological principles necessary for studying personality coherence dynamics are outlined in detail. This paper also addresses: (i) research methods for relating personality coherence/incoherence to behavioral consistency/inconsistency, and (ii) situational contexts that are important to these personality dynamics. In addition, personality coherence dynamics in relation to the self and character and the impact of the C-SAP assumption that behaviors are more stable than traits/types on the relation between personality coherence and behavioral consistency are discussed.

Behavioral Consistency in the Digital Age

Efforts to infer personality from digital footprints have focused on behavioral stability at the trait level without considering situational dependency. We repeated a classic study of intraindividual consistency with secondary data (five data sets) containing 28,692 days of smartphone usage from 780 people. Using per-app measures of pickup frequency and usage duration, we found that profiles of daily smartphone usage were significantly more consistent when taken from the same user than from different users (d > 1.46). Random-forest models trained on 6 days of behavior identified each of the 780 users in test data with 35.8% accuracy for pickup frequency and 38.5% accuracy for duration frequency. This increased to 73.5% and 75.3%, respectively, when success was taken as the user appearing in the top 10 predictions (i.e., top 1%). Thus, situation-dependent stability in behavior is present in our digital lives, and its uniqueness provides both opportunities and risks to privacy.

Environmental temperature during early life affects the personality of mosquitofish in adulthood

Personality has been observed in a variety of animal taxa with important implications in ecology and evolution. Exploring the influence of environmental temperature during early life on personality could help to understand the ontogeny of this phenotypic trait in animals. In this study, we reared newborn mosquitofish Gambusia affinis at high (30°C) and low (25°C) water temperatures and measured their shyness and exploration upon sexual maturity. We tested the repeatability of each behavioral trait; the correlation between them; and the effects of rearing temperature, sex, and body length on the behaviors. When growing up at low temperatures, female fish exhibited repeatability in shyness and exploration, and males exhibited marginal repeatability in shyness. However, neither of the 2 behaviors were repeatable when the fish were reared at high temperatures. There was a negative correlation between shyness and exploration, indicating that the 2 behaviors comprise a behavioral syndrome in this species. Mosquitofish reared at high temperatures were more explorative than those reared at low temperatures, while there was no difference in shyness between the 2 treatments. Body length and sex had no significant effects on the average values of the 2 behaviors. The results indicate that environmental temperature during early life could shape the personality of mosquitofish and modify the average of the behavioral traits. These findings might provide insights to understand the ontogeny of animal personality and how changes in environmental temperature influence animal dispersal by shaping their personality.

The ontogeny of personality: Repeatability of social and escape behaviors across developmental stages in Siberian hamsters (Phodopus sungorus)

Animal personality is defined as behavioral tendencies that are consistent across time and contexts within an individual, but differ across individuals. Studies investigating personality typically examine individuals across short time periods or within a single life stage. Growing evidence suggests that personality may be less stable across life stages, highlighting the need to consider the effects of ontogeny on the expression of consistent behavioral traits. We investigated individual consistency in social and escape behaviors across developmental stages using Siberian hamsters (Phodopus sungorus). To determine whether individuals were consistent in these behaviors as juveniles and across developmental stages, we measured male and female social and escape behaviors twice as juveniles and once as adults. Individuals' social scores were significantly repeatable within the juvenile stage, but not across developmental stages. In contrast, escape scores were highly repeatable across developmental stages, with males' scores being more repeatable than females' scores. Our results support previous findings that personality traits, especially those associated with social behavior, are less stable across development, whereas behaviors associated with stress or coping may represent a more permanent feature of an individual's phenotype. Our results also indicate potential sex differences in long-term repeatability of personality. Considering how ontogeny affects animal personality for males and females can provide insight into the evolution and mechanisms that maintain animal personality.

The effect of social environment on bird song: listener-specific expression of a sexual signal

Animal signals should consistently differ among individuals to convey distinguishable information about the signalers. However, behavioral display signals, such as bird song are also loaded with considerable within-individual variance with mostly unknown function. We hypothesized that the immediate social environment may play a role in mediating such variance component, and investigated in the collared flycatcher (Ficedula albicollis) if the identity and quality of listeners could affect song production in signalers. After presenting territorial males with either a female or male social stimulus, we found in the subsequent song recordings that the among-stimulus effects corresponded to non-zero variance components in several acoustic traits indicating that singing males are able to plastically adjust their songs according to stimulus identity. Male and female stimuli elicited different responses as the identity of the female stimuli affected song complexity only, while the identity of male stimuli altered also song length, maximum frequency, and song rate. The stimulus-specific effect on song in some cases decreased with time, being particularly detectable right after the removal of the stimulus and ceasing later, but this pattern varied across the sex of the stimulus and the song traits. We were able to identify factors that can explain the among-stimulus effects (e.g., size and quality of the stimuli) with roles that also varied among song traits. Our results confirm that the variable social environment can raise considerable variation in song performance, highlighting that within-individual plasticity of bird song can play important roles in sexual signaling.

Primates got personality, too: Toward an integrative primatology of consistent individual differences in behavior

In recent years, research on animal personality has exploded within the field of behavioral ecology. Consistent individual differences in behavior exist in a wide range of species, and these differences can have fitness consequences and influence several aspects of a species' ecology. In comparison to studies of other animals, however, there has been relatively little research on the behavioral ecology of primate personality. This is surprising given the large body of research within psychology and biomedicine showing that primate personality traits are heritable and linked to health and life history outcomes. In this article, I bring together theoretical perspectives on the ecology and evolution of animal personality with an integrative review of what we know about primate personality from studies conducted on captive, free-ranging, and wild primates. Incorporating frameworks that emphasize consistency in behavior into primate behavioral ecology research holds promise for improving our understanding of primate behavioral evolution.

MATCH: A New Approach for Differentiating & Linking Series of Sex Worker Homicides and Sexual Assaults

Sex workers as a group are one of the more common targets in serial homicide, yet the most likely to go unsolved. Part of the reason for this is the difficulty in linking individual crime scenes to a series, especially in those series where offenders not only target sex worker victims but also target non-sex worker victims. Inconsistencies in both victim targeting and behaviors engaged in across series add to the difficulties of linking and solvability in these types of crimes. The current study aimed to add to the current body of literature on serial crime linkage by examining not only the most salient behavioral indicators useful for crime scene classification of serial homicides that involve sex worker victims but also examine the trajectories of behavioral change that can help link apparently inconsistent crime scenes and proposes the new Model for the Analysis of Trajectories and Consistency in Homicide (MATCH). The study examines 83 homicide series, including 44 (53%) series where all victims were sex workers and 39 (47%) series that included a mix of sex workers and non-sex worker victims. Using the MATCH system allowed for the majority of series to be classified to a dominant trajectory pattern, over half as many as a traditional consistency analysis that focusses on behavioral similarity matching. Results further showed that Sex Worker Victim series were almost three times more consistent across their series than Mixed-Victim series, not only in victim selection but also in the overall behavioral patterns. Findings are discussed in line with theoretical and psychological issues relating to understanding the nature of behavioral consistency and the importance of going beyond simple matching toward a model that allows for the identification of consistency in seemingly inconsistent series, as well as investigative implications relating to linking serial crimes.

Urbanization and the temporal patterns of social networks and group foraging behaviors

Urbanization causes dramatic and rapid changes to natural environments, which can lead the animals inhabiting these habitats to adjust their behavioral responses. For social animals, urbanized environments may alter group social dynamics through modification of the external environment (e.g., resource distribution). This might lead to changes in how individuals associate or engage in group behaviors, which could alter the stability and characteristics of social groups. However, the potential impacts of urban habitat use, and of habitat characteristics in general, on the nature and stability of social associations remain poorly understood. Here, we quantify social networks and dynamics of group foraging behaviors of black-capped chickadees (N = 82, Poecile atricapillus), at four urban and four rural sites weekly throughout the nonbreeding season using feeders with radio frequency identification of individual birds. Because anthropogenic food sources in urban habitats (e.g., bird feeders) provide abundant and reliable resources, we predicted that social foraging associations may be of less value in urban groups, and thus would be less consistent than in rural groups. Additionally, decreased variability of food resources in urban habitats could lead to more predictable foraging patterns (group size, foraging duration, and the distribution of foraging events) in contrast to rural habitats. Networks were found to be highly consistent through time in both urban and rural habitats. No significant difference was found in the temporal clumping of foraging events between habitats. However, as predicted, the repeatability of the clumping of foraging events in time was significantly higher in urban than rural habitats. Our results suggest that individuals living in urban areas have more consistent foraging behaviors throughout the nonbreeding season, whereas rural individuals adjust their tactics due to less predictable foraging conditions. This first examination of habitat-related differences in the characteristics and consistency of social networks along an urbanization gradient suggests that anthropic habitat use results in subtle modifications in social foraging patterns. Future studies should examine potential implications of these differences for variation in predation risk, energy intake, and information flow.

Consistent differences in foraging behavior in 2 sympatric harvester ant species may facilitate coexistence

The co-occurrence of 2 similar species depends on their ability to occupy different ecological niches. Here, we compared the consistency of different aspects of foraging behavior in 2 co-occurring harvester ant species (Messor ebeninus and Messor arenarius), under field conditions. The 2 species are active concomitantly and display a similar diet, but M. arenarius features smaller colonies, larger workers on average, and a broader range of foraging strategies than M. ebeninus. We characterized the flora in the 2 species' natural habitat, and detected a nesting preference by M. arenarius for more open, vegetation-free microhabitats than those preferred by M. ebeninus. Next, we tested the food preference of foraging colonies by presenting 3 non-native seed types. Messor arenarius was more selective in its food choice. Colonies were then offered 1 type of seeds over 3 days in different spatial arrangements from the nest entrance (e.g., a seed plate close to the nest entrance, a seed plate blocked by an obstacle, or 3 plates placed at increasing distances from the nest entrance). While both species were consistent in their foraging behavior, expressed as seed collection, under different treatments over time, M. ebeninus was more consistent than M. arenarius. These differences between the species may be explained by their different colony size, worker size, and range of foraging strategies, among other factors. We suggest that the differences in foraging, such as in food preference and behavioral consistency while foraging, could contribute to the co-occurrence of these 2 species in a similar habitat.

The power of putting a label on it: green labels weigh heavier than contradicting product information for consumers' purchase decisions and post-purchase behavior

Green products are appealing. Thus, labeling products as environmentally friendly is an effective strategy to increase sales. However, the labels often promise more than the products can actually deliver. In the present research, we examined the expectation that consumers with high ecological motivation have strong preferences for green-labeled products – even when presented product information contradicts the label’s image. This unsettling hypothesis is grounded in the labels’ potential to create a cognitive match between the labeled product and consumers’ motives. For labels indicating environmental friendliness (green product labels), this link should be strongest when consumers’ ecological motivation is high. Findings in a series of three experiments support our assumption, showing that consumers with high ecological motivation had strong preferences (i.e., product evaluations, purchase intentions, and simulated purchase decisions) for green-labeled products as compared to consumers with low ecological motivation (Studies 1–3). Crucially, these preferences were robust, despite contradicting environmental product information (Studies 1 and 2). We extended our findings by additionally examining the impact of product labels and motivation on moral self-regulation processes. This was established by assessing participants’ pro-social behavior after the purchase task: participants with high ecological motivation acted, consistent with their motives, more pro-socially in post-decision occasions. In accordance with moral cleansing effects, pro-social behavior was intensified after purchasing conventional products (Studies 2 and 3). Green labels protected participants with high ecological motivation from moral threats due to the purchase, thus making pro-social behavior less likely. Findings suggest that highly ecologically motivated consumers are most susceptible to green labels, which may override detailed product information.

Individual Consistency of Feather Pecking Behavior in Laying Hens: Once a Feather Pecker Always a Feather Pecker?

The pecking behavior [severe feather, gentle feather, and aggressive pecks (AP)] of individual White Shaver non-cage laying hens (n = 300) was examined at 21, 24, 27, 32, and 37 weeks. Hens were housed in 30 groups of 10 hens each and on 3 cm litter with access to a feeder, perch, and two nest boxes. The number of severe feather pecks given (SFPG) and received (SFPR) was used to categorize hens as feather peckers (P), victims (V), neutrals (N), or feather pecker-victims (PV) at each age. Hens categorized as PV exhibited pecking behaviors similar to P and received pecks similar to V. SFP given were correlated with APs given, but not with gentle feather pecks (GFP) given throughout the study. State-transition plot maps illustrated that 22.5% of P remained P, while 44% of PV remained PV throughout the duration of the study. Lifetime behavioral categories identified hens as a consistent feather pecker (5%), consistent neutral (3.9%), consistent victim (7.9%), consistent feather pecker-victim (29.4%), or inconsistent (53.8%) in their behavioral patterns throughout their life. Consistent feather peckers performed more SFP than hens of other categories, and consistent neutral hens received fewer GFP than consistent feather PV. No differences in corticosterone or whole blood serotonin levels were observed among the categories. Approximately, half of the population was classified as a feather pecker at least once during the study, while the remainder was never categorized as a feather pecker. Therefore, even if the development and cause of feather pecking may be multifactorial, once the behavior has been developed, some hens may persist in feather pecking. However, as some hens were observed to never receive or perform SFP, emphasis should be made to select for these hens in future breeding practices.