The role of social status and testosterone in human conspicuous consumption

Conspicuous consumption refers to the phenomenon where individuals purchase goods for signalling social status, rather than for its inherent functional value. This study (n = 166 male participants) investigated how the outcome of a social competition influenced conspicuous consumption, and its association with competition-induced testosterone reactivity. Winning a competition increased both explicit and implicit preferences for higher-status vs. lower-status products, using both natural stimuli (prestigious cars) and laboratory-tagged stimuli of matched value (university T-shirts). Competition also influenced behaviour in an Ultimatum Game, such that winners were more likely to reject unfair offers. Competition outcomes had no discernible influence upon salivary testosterone levels, and neither basal testosterone levels nor testosterone reactivity induced by competition predicted the conspicuous consumption measures. Our data indicate that winning a competition lead to more dominant behaviour, albeit in a manner that is not statistically regulated by testosterone, possibly through increased feeling of entitlement.This work was completed within the University of Cambridge Behavioural and Clinical Neuroscience Institute (director: TW Robbins), supported by a consortium award from the Medical Research Council (MRC Ref G1000183) and Wellcome Trust (WT Ref 093875/Z/10/Z). YW was supported by the Treherne Studentship in Biological Sciences from Downing College, Cambridge, National Natural Science Foundation of China (31600923), Shenzhen University Natural Science Research Fund (2016073) and Shenzhen University Social and Humanity Science Research Fund (17QNFC44). CE was supported by the Vienna Science and Technology Fund (WWTF VRG13-007). The Centre for Gambling Research at UBC is supported by the British Columbia Lottery Corporation and the British Columbia Government

When Models Interact with their Subjects: The Dynamics of Model Aware Systems

A scientific model need not be a passive and static descriptor of its subject. If the subject is affected by the model, the model must be updated to explain its affected subject. In this study, two models regarding the dynamics of model aware systems are presented. The first explores the behavior of "prediction seeking" (PSP) and "prediction avoiding" (PAP) populations under the influence of a model that describes them. The second explores the publishing behavior of a group of experimentalists coupled to a model by means of confirmation bias. It is found that model aware systems can exhibit convergent random or oscillatory behavior and display universal 1/f noise. A numerical simulation of the physical experimentalists is compared with actual publications of neutron life time and {\Lambda} mass measurements and is in good quantitative agreement.Comment: Accepted for publication in PLoS-ON

Effects of dopamine D2/D3 receptor antagonism on human planning and spatial working memory

Psychopharmacological studies in humans suggest important roles for dopamine (DA) D2 receptors in human executive functions, such as cognitive planning and spatial working memory (SWM). However, studies that investigate an impairment of such functions using the selective DA D2/3 receptor antagonist sulpiride have yielded inconsistent results, perhaps because relatively low doses were used. We believe we report for the first time, the effects of a higher (800 mg p.o.) single dose of sulpiride as well as of genetic variation in the DA receptor D2 gene (DA receptor D2 Taq1A polymorphism), on planning and working memory. With 78 healthy male volunteers, we apply a between-groups, placebo-controlled design. We measure outcomes in the difficult versions of the Cambridge Neuropsychological Test Automated Battery One-Touch Stockings of Cambridge and the self-ordered SWM task. Volunteers in the sulpiride group showed significant impairments in planning accuracy and, for the more difficult problems, in SWM. Sulpiride administration speeded response latencies in the planning task on the most difficult problems. Volunteers with at least one copy of the minor allele (A1+) of the DA receptor D2 Taq1A polymorphism showed better SWM capacity, regardless of whether they received sulpiride or placebo. There were no effects on blood pressure, heart rate or subjective sedation. In sum, a higher single dose of sulpiride impairs SWM and executive planning functions, in a manner independent of the DA receptor D2 Taq1A polymorphism.This research work was funded by a Core Award from the Medical Research Council and the Wellcome Trust to the Behavioural and Clinical Neuroscience Institute (MRC Ref G1000183; WT Ref 093875/Z/10/Z). Also supported by a Wellcome Trust Senior Investigator Award (104631/Z/14/Z) awarded to TWR. CE was supported by the Swiss National Science Foundation (PA00P1_134135) and the Vienna Science and Technology Fund (WWTF VRG13-007)

Role of Dopamine D2 Receptors in Human Reinforcement Learning

Influential neurocomputational models emphasize dopamine (DA) as an electrophysiological and neurochemical correlate of reinforcement learning. However, evidence of a specific causal role of DA receptors in learning has been less forthcoming, especially in humans. Here we combine, in a between-subjects design, administration of a high dose of the selective DA D2/3-receptor antagonist sulpiride with genetic analysis of the DA D2 receptor in a behavioral study of reinforcement learning in a sample of 78 healthy male volunteers. In contrast to predictions of prevailing models emphasizing DA's pivotal role in learning via prediction errors, we found that sulpiride did not disrupt learning, but rather induced profound impairments in choice performance. The disruption was selective for stimuli indicating reward, while loss avoidance performance was unaffected. Effects were driven by volunteers with higher serum levels of the drug, and in those with genetically-determined lower density of striatal DA D2 receptors. This is the clearest demonstration to date for a causal modulatory role of the DA D2 receptor in choice performance that might be distinct from learning. Our findings challenge current reward prediction error models of reinforcement learning, and suggest that classical animal models emphasizing a role of postsynaptic DA D2 receptors in motivational aspects of reinforcement learning may apply to humans as well.Neuropsychopharmacology accepted article peview online, 09 April 2014; doi:10.1038/npp.2014.84

Altered social and non-social decision-making in recreational and dependent cocaine users

Background Maladaptive decision-making is assumed to be a core feature of cocaine addiction. Indeed, numerous studies have reported deficits in non-social decision-making tasks and reward-related impulsivity in dependent cocaine users. However, social decision-making has not been examined in cocaine users yet. Moreover, it is unknown if even recreational and non-dependent cocaine use is linked to decision-making deficits. Therefore, we investigated whether recreational and dependent cocaine users exhibit alterations in social and non-social decision-making. Method The performance of healthy controls (n=68), recreational cocaine users (n=68) and dependent cocaine users (n=30) in classical decision-making paradigms (Iowa Gambling Task, Delay Discounting) and in social interaction paradigms (Distribution Game, Dictator Game) was assessed. Results Decisions in the social interaction tasks of both cocaine user groups were more self-serving compared with controls as cocaine users preferred higher monetary payoffs for themselves. In the Iowa Gambling Task, only dependent cocaine users were more likely to choose disadvantageous card decks, reflecting worse decision-making. They were also more likely to choose immediate smaller rewards over larger delayed rewards in the Delay Discounting task. Conclusions Our results imply that both recreational and dependent cocaine users are more concerned with their own monetary gain when interacting with another person. Furthermore, primarily dependent cocaine users are less foresighted and more impulsive regarding immediate reward. Overall, social interaction deficits are already present in recreational users, while non-social decision-making deficits occur predominantly in dependent cocaine users. Thus, social interaction training and cognitive remediation strategies may improve treatment success and quality of life in cocaine dependenc

An exploration of the relationships among facial dimensions, age, sex, dominance status and personality in rhesus macaques (Macaca mulatta)

Aspects of personality in nonhuman primates have been linked to health, social relationships, and life history outcomes. In humans as well as nonhuman primates, facial morphology is associated with assertiveness, aggression, and measures of dominance status. In this study we aimed to examine the relationship among facial morphology, age, sex, dominance status, and ratings on the personality dimensions Confidence, Openness, Assertiveness, Friendliness, Activity, and Anxiety in rhesus macaques (Macaca mulatta). We measured facial width-to-height ratio (fWHR) and lower-height/full-height ratio (fLHFH) using photographs from 109 captive rhesus macaques, which observers also assessed for dominance status and personality, and explored the associations among facial morphology, age, sex, dominance status, and personality. fWHR and fLHFH personality associations depended on age category: Assertiveness was associated with higher fWHR and fLHFH, and Confidence was associated with lower fWHR and fLHFH, but all these associations were consistent only in individuals <8 yr. of age. We found fWHR and fLHFH to not be consistently associated with sex or dominance status; compared to younger individuals, we found few associations with fWHR and fLHFH for individuals older than 8 yr., which may be due to limited sample size. Our results indicate that in macaques <8 yr. old, facial morphology is associated with the Assertiveness and Confidence personality dimensions, which is consistent with results suggesting a relationship between fWHR and trait aggression in humans and assertiveness in brown capuchins, all of which implies that fWHR might be a cue to assertive and aggressive traits

Task-Dependent Interaction between Parietal and Contralateral Primary Motor Cortex during Explicit versus Implicit Motor Imagery

Both mental rotation (MR) and motor imagery (MI) involve an internalization of movement within motor and parietal cortex. Transcranial magnetic stimulation (TMS) techniques allow for a task-dependent investigation of the interhemispheric interaction between these areas. We used image-guided dual-coil TMS to investigate interactions between right inferior parietal lobe (rIPL) and left primary motor cortex (M1) in 11 healthy participants. They performed MI (right index-thumb pinching in time with a 1 Hz metronome) or hand MR tasks, while motor evoked potentials (MEPs) were recorded from right first dorsal interosseous. At rest, rIPL conditioning 6 ms prior to M1 stimulation facilitated MEPs in all participants, whereas this facilitation was abolished during MR. While rIPL conditioning 12 ms prior to M1 stimulation had no effect on MEPs at rest, it suppressed corticomotor excitability during MI. These results support the idea that rIPL forms part of a distinct inhibitory network that may prevent unwanted movement during imagery tasks

The intergenerational association between parents' problem gambling and impulsivity-hyperactivity/inattention behaviors in children

Despite the well-established association between problem gambling and ADHD core categories of impulsivity-hyperactivity and inattention, the link between parents’ problem gambling and impulsivity-hyperactivity/inattention (IH/I) behaviors in children has not been investigated. This study investigated the association between parents’ problem gambling and children’s IH/I behaviors while controlling for potential confounding variables. A population-based prospective cohort followed-up from kindergarten to age 30, the Quebec Longitudinal Study of Kindergarten Children (QLSKC), provided data over three generations. Among 1358 participants at age 30, parents with a child aged 1 year or older (N=468; Mean age=4.65 years; SD=2.70) were selected. Generalized Linear Models included measures of grandparents’ and parents’ problem gambling, parents’ IH/I behaviors in childhood, and a host of risk factors and comorbidities to predict IH/I in children. Intergenerational bivariate associations were observed between grandparents’ problem gambling, parents’ IH/I in childhood and problem gambling at age 30, and between parents’ IH/I, problem gambling, and children’s IH/I behaviors. Parents’ problem gambling predicted children’s IH/I behaviors above and beyond the effects of covariates such as family and socioeconomic characteristics, alcohol and drug use, depression symptoms and parents’ gambling involvement. Parents’ IH/I behaviors in childhood also predicted children’s IH/I and had a moderating, enhancing effect on parents’ problem gambling association with their offspring’s IH/I behaviors. Problem gambling is a characteristic of parents’ mental health that is distinctively associated with children’s IH/I behaviors, above and beyond parents’ own history of IH/I and of typically related addictive, psychopathological or socioeconomic risk factors and comorbidities