Determining the effects of training duration on the behavioral expression of habitual control in humans: a multilaboratory investigation

It has been suggested that there are two distinct and parallel mechanisms for controlling instrumental behavior in mammals: goal-directed actions and habits. To gain an understanding of how these two systems interact to control behavior, it is essential to characterize the mechanisms by which the balance between these systems is influenced by experience. Studies in rodents have shown that the amount of training governs the relative expression of these two systems: Behavior is goal-directed following moderate training, but the more extensively an instrumental action is trained, the more it becomes habitual. It is less clear whether humans exhibit similar training effects on the expression of goal-directed and habitual behavior, as human studies have reported contradictory findings. To tackle these contradictory findings, we formed a consortium, where four laboratories undertook a preregistered experimental induction of habits by manipulating the amount of training. There was no statistical evidence for a main effect of the amount of training on the formation and expression of habits. However, exploratory analyses suggest a moderating effect of the affective component of stress on the impact of training over habit expression. Participants who were lower in affective stress appeared to be initially goal-directed, but became habitual with increased training, whereas participants who were high in affective stress were already habitual even after moderate training, thereby manifesting insensitivity to overtraining effects. Our findings highlight the importance of the role of moderating variables such as individual differences in stress and anxiety when studying the experimental induction of habits in humans.

Experimental Induction of Tenacibaculosis in Atlantic Salmon (Salmo salar L.) Using Tenacibaculum maritimum, T. dicentrarchi, and T. finnmarkense

There is a limited understanding of the pathogenesis of tenacibaculosis in Atlantic salmon (Salmo salar L.) and there are few reproducible exposure models for comparison. Atlantic salmon were exposed via bath to Tenacibaculum maritimum, T. dicentrarchi, or T. finnmarkense, and were then grouped with naïve cohabitants. Mortalities had exaggerated clinical signs of mouthrot, a presentation of tenacibaculosis characterized by epidermal ulceration and yellow plaques, on the mouth and less frequently on other tissues. Histopathology showed tissue spongiosis, erosion, ulceration, and necrosis ranging from mild to marked, locally to regionally extensive with mats of intralesional bacteria on the rostrum, vomer, gill rakers, gill filaments, and body surface. Exposure to T. maritimum resulted in less than a 0.4 probability of survival for both exposed and cohabitants until Day 21. Exposures to T. dicentrarchi resulted in 0 and 0.55 (exposed), and 0.8 and 0.9 (cohabitant) probability of survival to Day 12 post-exposure, while T. finnmarkense had a 0.9 probability of survival to Day 12 for all groups. This experimental infection model will be useful to further investigate the pathogenesis of tenacibaculosis, its treatment, and immunity to Tenacibaculum species.

Experimental induction of resins as a tool to understand variability in ambers

Amber is chiefly known as a preservational medium of biological inclusions, but it is itself a chemofossil, comprised of fossilised plant resin. The chemistry of today's resins has been long investigated as a means of understanding the botanical sources of ambers. However, little is known about the chemical variability of resins and consequently about that of the ambers that are derived from particular resins. We undertook experimental resin production in Araucariacean plants to clarify how much natural resin variability is present in two species, Agathis australis and Wollemia nobilis, and whether different resin exudation stimuli types can be chemically identified and differentiated. The latter were tested on the plants, and the resin exudates were collected and investigated with Fourier-transform infrared attenuated total reflection (FTIR-ATR) spectroscopy to give an overview of their chemistry for comparisons, including multivariate analyses. The Araucariacean resins tested did not show distinct chemical signatures linked to a particular resin-inducing treatment. Nonetheless, we did detect two separate groupings of the treatments for Agathis, in which the branch removal treatment and mimicked insect-boring treatment-derived resin spectra were more different from the resin spectra derived from other treatments. This appears linked to the lower resin viscosities observed in the branch- and insect-treatment-derived resins. However the resins, no matter the treatment, could be distinguished from both species. The effect of genetic variation was also considered using the same stimuli on both the seed-grown A. australis derived from wild-collected populations and on clonally derived W. nobilis plants with natural minimal genetic diversity. The variability in the resin chemistries collected did reflect the genetic variability of the source plant. We suggest that this natural variability needs to be taken into account when testing resin and amber chemistries in the future.

Human sickness detection is not dependent on cultural experience

Animals across phyla can detect early cues of infection in conspecifics, thereby reducing the risk of contamination. It is unknown, however, if humans can detect cues of sickness in people belonging to communities with whom they have limited or no experience. To test this, we presented Western faces photographed 2 h after the experimental induction of an acute immune response to one Western and five non-Western communities, including small-scale hunter–gatherer and large urban-dwelling communities. All communities could detect sick individuals. There were group differences in performance but Western participants, who observed faces from their own community, were not systematically better than all non-Western participants. At odds with the common belief that sickness detection of an out-group member should be biased to err on the side of caution, the majority of non-Western communities were unbiased. Our results show that subtle cues of a general immune response are recognized across cultures and may aid in detecting infectious threats.

Using the Judgment Bias Task to Identify Behavioral Indicators of Affective State: Do Eye Wrinkles in Horses Reflect Mood?

Identifying and validating behavioral indicators of mood are important for the assessment of animal welfare. Here, we investigated whether horses' eye wrinkle expression in a presumably neutral situation is a measure of mood as assessed in a cognitive judgment bias task (JBT). To this end, we scored pictures of the left and right eyes of 16 stallions for different aspects of eye wrinkle expression and tested the same individuals on a spatial JBT with active trial initiation. Eye wrinkle expressions were assessed by a qualitative assessment, i.e., the overall assessment of how “worried” horses look, the number of wrinkles, and the angle measured at the intersection of lines drawn through the eyeball and the topmost wrinkle. Correlations between the three eye wrinkle measures and the optimism index as a measure of horses' decisions in the JBT were not statistically significant, but with increasing optimism index, horses tended to be scored as looking less worried (qualitative assessment). We discuss our findings from different perspectives and make suggestions for future research, e.g., by calling for experimental induction of mood and thus greater variation within and/or between individuals and by investigating the interplay between shorter-lasting emotional and longer-lasting mood states to further explore the potential use of the JBT to validate eye wrinkles and other facial or body expressions as indicators of mood.

Wise reasoning, intergroup positivity, and attitude polarization across contexts

We hypothesized that a wisdom-based reasoning process comprised of epistemic humility, accounting for context, and integrating different perspectives and interests, would be helpful in overcoming intergroup bias and attitude polarization in societal conflicts. Here we test the hypothesis using both the Situated Wise Reasoning Scale and experimental induction. In each study, we recruited participants who self-identified as members of a group implicated in an ongoing intergroup situation. In five correlational studies (Studies 1-5) we examined the relations between measured wise reasoning and intergroup positivity and attitude polarization. In two experiments, we tested the effects of a brief online wise-reasoning thought exercise on intergroup positivity and polarization (Studies 6-7), and charitable behaviors to an outgroup (Study 6). We found that wise reasoning relates to more positivity toward outgroups and less attitude polarization across different groups and conflicts. The results have implications for theory and may also have implications for future research on interventions to improve intergroup relations.