Shifted risk preferences in pathological gambling.

BACKGROUND: Pathological gambling (PG) is an impulse control disorder characterized by excessive monetary risk seeking in the face of negative consequences. We used tools from the field of behavioral economics to refine our description of risk-taking behavior in pathological gamblers. This theoretical framework allowed us to confront two hypotheses: (1) pathological gamblers distort winning probabilities more than controls; and (2) pathological gamblers merely overweight the whole probability range. Method Eighteen pathological gamblers and 20 matched healthy participants performed a decision-making task involving choices between safe amounts of money and risky gambles. The online adjustment of safe amounts, depending on participants' decisions, allowed us to compute 'certainty equivalents' reflecting the subjective probability weight associated with each gamble. The behavioral data were then fitted with a mathematical function known as the 'probability weighting function', allowing us to disentangle our two hypotheses. RESULTS: The results favored the second hypothesis, suggesting that pathological gamblers' behavior reflects economic preferences globally shifted towards risk, rather than excessively distorted probability weighting. A mathematical parameter (elevation parameter) estimated by our fitting procedure was found to correlate with gambling severity among pathological gamblers, and with gambling affinity among controls. CONCLUSIONS: PG is associated with a specific pattern of economic preferences, characterized by a global (i.e. probability independent) shift towards risky options. The observed correlation with gambling severity suggests that the present 'certainty equivalent' task may be relevant for clinical use.

The influence of prior expectations on facial expression discrimination in schizophrenia.

BACKGROUND: Belief inflexibility is a thinking style observed in patients with schizophrenia, in which patients tend to refute evidence that runs counter to their prior beliefs. This bias has been related to a dominance of prior expectations (prior beliefs) over incoming sensory evidence. In this study we investigated the reliance on prior expectations for the processing of emotional faces in schizophrenia. METHOD: Eighteen patients with schizophrenia and 18 healthy controls were presented with sequences of emotional (happy, fearful, angry or neutral) faces. Perceptual decisions were biased towards a particular expression by a specific instruction at the start of each sequence, referred to as the context in which stimuli occurred. Participants were required to judge the emotion on each face and the effect of the context on emotion discrimination was investigated. RESULTS: For threatening emotions (anger and fear), there was a performance cost for facial expressions that were incongruent with, and perceptually close to, the expression named in the instruction. For example, for angry faces, participants in both groups made more errors and reaction times (RTs) were longer when they were asked to look out for fearful faces compared with the other contexts. This bias against sensory evidence that runs counter to prior information was stronger in the patients, evidenced by a group by context interaction in accuracy and RTs for anger and fear respectively. CONCLUSIONS: Overall, the present data suggest an overdependence on prior expectations for threatening stimuli, reflecting belief inflexibility, in schizophrenia.

[Risk-taking in adolescence: A neuroeconomics approach]. / Approche neuroéconomique de la prise de risque à l'adolescence.

OBJECTIVE: Risk-taking behaviors represent the main cause of morbi-mortality in adolescence. Here, we analyze their neural correlates, based on a neuroeconomics approach. This approach postulates that risk-taking behaviors result from multiple decision-making biases that impair the selection of the most appropriate action among alternatives based on their subjective evaluation. Specifically, we investigate three important domains in value-based decision-making: risk aversion, loss aversion and intertemporal choice. LITERATURE FINDINGS: First, when people have to make a decision between two rewarding options, they will usually prefer the more certain, even possibly lower, option - a phenomenon called "risk aversion". Yet adolescent people have been found to be less averse to risk than adults. This observation was linked to hypoactivation in (1) the anterior insula, involved in negative emotion such as fear and disgust and (2) the anterior cingular and the posterior ventromedial prefrontal cortices, involved in the monitoring of conflict and error detection. Second, people are generally described as being more sensitive to the possibility of losing objects than to that of gaining the same objects - "loss aversion". Here, we suggest that adolescents may be less averse to losses than adults when estimating the prospects of gaining and losing objects. Indeed, adolescent people have been found to be more affected by reward (e.g. euphoria or social integration consecutive to drug absorption) and less affected by punishment (e.g. malaise after drug consumption) than adults. Whereas the former process is subserved by hyperactivations in regions involved in reward evaluation such as the nucleus accumbens, the latter has been proposed to be subserved by hypoactivations in regions involved in negative emotions such as the amygdala or the insular cortex. This lower sensitivity to losses compared to gains in adolescents could be another important mechanism underlying risk-taking behaviors. A third dimension of adolescents' decision-making biases is temporality. It has been shown that adolescents favor immediate over delayed prospects, reflecting how future consequences of their decisions are heavily discounted. For example, adolescents can fail in projecting the future benefits of having safe sex - and thereby avoiding the risk of sexually transmitted disease or pregnancy - being more interested in the immediate reward of having romantic uninterrupted sexual intercourse. This impairment in inhibiting the choice of the early alternative could be related to the hypofunctionality of the lateral prefrontal cortex. Importantly, these three biases in the evaluation of decisions by adolescents may be related to the maturation of two neuronal systems. On the one hand, the early reorganization of dopaminergic neurons in the motivational system, due to the brutal secretion of sex hormones (mostly estrogens, testosterone and oxytocin) at the beginning of puberty, impels adolescents toward thrill seeking. On the other hand, the slow maturation of the cognitive control system, mostly exerted by the prefrontal cortex, implies that these impulses cannot be appropriately regulated. CONCLUSIONS: Two important neurodevelopmental mechanisms are thought to play a key role in the genesis of risk-taking behaviors in adolescence: the brutal secretion of sex hormones at the beginning of puberty and the delayed maturation of cognitive control. As such, these behaviors can be considered as inevitable, even if other factors, like sex, heredity and precariousness, can enhance their frequency. The implications of these conclusions for the prevention of risk-taking behaviors in adolescence are discussed.