Alcohol use and discounting of delayed and probabilistic gain and loss.

OBJECTIVE: Little is known about the relationship between alcohol and discounting of loss, one of procrastinative behaviors. This study examined the relationship between the frequency of alcohol use and discounting delayed and probabilistic gain and loss, which is of interest in neuroeconomics of addiction. METHODS: Thirty-three subjects conducted tasks of delay and probability discounting of gain and loss. Their alcohol use was also assessed. RESULTS: The frequency of alcohol use was significantly correlated with the degree to which delayed monetary losses were discounted. CONCLUSIONS: Frequent use of alcohol may associate with an increased degree of procrastination. Further, the degrees of delay discounting of loss could be a predictor of a frequent alcohol intake.

Depressive patients are more impulsive and inconsistent in intertemporal choice behavior for monetary gain and loss than healthy subjects--an analysis based on Tsallis' statistics.

OBJECTIVES: Depression has been associated with impaired neural processing of reward and punishment. However, to date, little is known regarding the relationship between depression and intertemporal choice (delay discounting) for gain and loss. This examination is potentially important for advances in neuroeconomics of intertemporal choice, because depression is associated with reduced serotonergic activities in the brain. DESIGN AND SETTING: We compared impulsivity and inconsistency in intertemporal choice for monetary gain and loss between depressive patients and healthy control subjects. METHODS: We conducted delay discounting tasks for gain and loss in depressed and healthy control subjects. We then quantified impulsivity and inconsistency in the delay discounting with parameters in the q-exponential discount function based on Tsallis' statistics. RESULTS: We observed that depressive patients were more impulsive and time-inconsistent in intertemporal choice action for gain and loss, in comparison to healthy controls. MAIN FINDINGS: Depressed patients were more irrational in temporal discounting. CONCLUSIONS: The usefulness of the q-exponential discount function for assessing the impaired decision-making by depressive patients was demonstrated. Furthermore, biophysical mechanisms underlying the altered intertemporal choice by depressive patients are discussed in relation to impaired serotonergic neural systems.

Comparison of probabilistic choice models in humans.

BACKGROUND: Probabilistic choice has been attracting attention in psychopharmacology and neuroeconomics. Several parametric models have been proposed for probabilistic choice; entropy model, Prelec's probability weight function, and hyperbola-like probability discounting functions. METHODS: In order to examine (i) fitness of the probabilistic models to behavioral data, (ii) relationships between the parameters and psychological processes, e.g., aversion to possible non-gain in each probabilistic choice and aversion to unpredictability, we estimated the parameters and AICc (Akaike Information Criterion with small sample correction) of the probabilistic choice models by assessing the points of subjective equality at seven probability values (95%-5%). We examined both fitness of the models parametrized by utilizing AICc, and the relationships between the model parameters and equation-free parameter of aversion to possible non-gain. RESULTS: Our results have shown that (i) the goodness of fitness for group data was [Entropy model>Prelec's function>General hyperbola>Simple hyperbola]; while Prelec's function best fitted individual data, (ii) aversion to possible non-gain and aversion to unpredictability are distinct psychological processes. CONCLUSION: Entropy and Prelec models can be utilized in psychopharmacological and neuroeconomic studies of risky decision-making.

Sex differences in the relationship between cortisol levels and the Empathy and Systemizing Quotients in humans.

OBJECTIVE: Little is known regarding the relationship between cortisol (a stress hormone) levels and psychological cognitive styles. Baron-Cohen proposed two fundamental cognitive styles, which are measured by the Empathy Quotient (EQ) and the Systemizng Quotient (SQ). Previous studies have examined the influences of prenatal testosterone exposure on EQ and SQ scores. This study aimed to examine the relationships between morning cortisol levels and EQ and SQ scores, and the 'brain types' which were determined by two quotients in both sexes. These relationships are potentially important in the developmental psychopathology of autism and neuroeconomics of empathy. METHODS: We assessed morning cortisol levels with LC/MS (liquid chromatography-mass spectrometry) and ESQ in healthy male and female university students. CONCLUSIONS: Results indicate clear sex differences between brain types: i.e. E-type males and S-type females (participants with atypical cognitive styles) have significantly higher cortisol levels than S-type males and E-type females (participants with typical cognitive styles). Implications for the role of sex in social adaptation of autistic patients are discussed.