Application of the symbolic regression program AI-Feynman to psychology.

The discovery of hidden laws in data is the core challenge in many fields, from the natural sciences to the social sciences. However, this task has historically relied on human intuition and experience in many areas, including psychology. Therefore, discovering laws using artificial intelligence (AI) has two significant advantages. First, it makes it possible to detect laws that humans cannot discover. Second, it will help construct more accurate theories. An AI called AI-Feynman was released in a very different field, and it performed impressively. Although AI-Feynman was initially designed to discover laws in physics, it can also work well in psychology. This research aims to examine whether AI-Feynman can be a new data analysis method for inter-temporal choice experiments by testing whether it can discover the hyperbolic discount model as a discount function. An inter-temporal choice experiment was conducted to accomplish these objectives, and the data were input into AI-Feynman. As a result, seven discount function candidates were proposed by AI-Feynman. One candidate was the hyperbolic discount model, which is currently considered the most accurate. The three functions of the root-mean-squared errors were superior to the hyperbolic discount model. Moreover, one of the three candidates was more "hyperbolic" than the standard hyperbolic discount function. These results indicate two things. One is that AI-Feynman can be a new data analysis method for inter-temporal choice experiments. The other is that AI-Feynman can discover discount functions that humans cannot find.

Quantitative Cross-Cultural Similarities and Differences in Social Discounting for Gains and Losses.

Social discounting is when resource allocation decreases as social distance increases. Studies fitting different quantitative models to social discounting data have shown that a q-exponential function based on Tsallis' statistics best fits loss data, whereas a hyperbolic power function best fits gain data. However, a social discounting sign effect, where losses are discounted less than equivalent gains, has not been consistently found. This study fit four different quantitative social discounting models to gain and loss data for 40 United States (US) participants. We compared quantitative model fits to previous studies collected with Japanese and German participants to determine if (1) different quantitative social discounting models best fit loss and gain data, (2) US participants discounted less gains than Japanese participants, but not losses, and (3) US participants showed the sign effect. Results showed that the q-exponential function and the hyperbolic power function best fit median loss and gain data, respectively. There were no significant absolute differences between cultures for gains or losses, and US participants showed a robust sign effect. While most results for US participants were consistent with previous data, future cross-cultural social discounting studies are needed that manipulate sign as well as reward magnitude to determine best quantitative model fits. Social discounting results are also discussed in relation to their application to important health behaviors such as smoking and obesity.

A New Analysis on Self-Control in Intertemporal Choice and Mediterranean Dietary Pattern.

This paper completes Muñoz Torrecillas et al. (1) results and conclusions investigating the relationship between adherence to healthy dietary habits, specifically the Mediterranean Diet (hereinafter, MD), and impulsivity in intertemporal choices. Impulsivity can be defined as the strong preference for small immediate payoffs over larger delayed payoffs, and in the original study this behavior was captured by the parameter k (discount rate of the hyperbolic discount function), calculated using an automated scoring mechanism. Adherence to MD was measured by the KIDMED index and then grouped into three levels: high, medium, and low. While the authors observed that individuals in the high adherence group had the shallowest discounting and individuals in the low adherence group had the steepest discounting, the data were not statistically analyzed in depth. Therefore, the purpose of the present paper is to propose a preliminary quantitative model for this relationship and evaluate its significance. Tests revealed a significant interaction between adherence to MD and magnitude of delayed rewards when predicting discount rates. Specifically, the degree to which impulsivity decreases as adherence to MD increases is strongly influenced by delayed rewards of smaller magnitude. These findings are consistent with the authors' claims that healthy dietary habits may be closely linked with greater self-control when payoffs are small, and thus warrant further examination. The results do not indicate causality though, so future studies could also investigate the directions of this relationship as a means of developing behavioral interventions.

Self-Control in Intertemporal Choice and Mediterranean Dietary Pattern.

Background: The Mediterranean Diet (hereinafter MD) is considered a healthy dietary pattern. Adherence to this pattern can be assessed by means of the KIDMED test by which individuals are assigned an index and classified into three groups of adherence to MD: high, medium, and low. In addition, impulsivity or impatience in intertemporal choice has been defined as a strong preference for small immediate rewards over large delayed ones. Objective: This study examines the relationship between dietary habits, specifically Mediterranean dietary pattern, measured by the KIDMED index, and the exhibited impatience in intertemporal choices, by means of the parameter k (discount rate of the hyperbolic discount function). Methods: A sample of 207 university students answered a questionnaire based on two tests: the KIDMED test, to assess the degree of adherence to MD, and an intertemporal choice questionnaire, to assess impatience or impulsivity. Individuals were grouped depending on their KIDMED score and then the discount rate or impulsivity parameter was calculated for each group. Results: Discount rates were inversely related to the degree of adherence to MD. The values of overall k were 1.53, 1.91, and 3.71% for the groups exhibiting high, medium and low adherence to MD, respectively. We also found higher k-values for larger rewards (magnitude effect) in the three groups. Conclusion: High adherence to MD is related to less steep time discounting, which implies less impulsivity (more self-control) or lower discount rates. Conversely, low adherence to MD is related to steeper time discounting, which implies impulsivity or higher discount rates. These findings could be used to identify the target population where policy interventions are needed in order to promote healthier diet habits.

Testosterone promotes either dominance or submissiveness in the Ultimatum Game depending on players' social rank.

Endogenous testosterone promotes behaviours intended to enhance social dominance. However, recent research suggests that testosterone enhances strategic social behaviour rather than dominance seeking behaviour. This possibility has not been tested in a population whose members are known to vary in social status. Here, we explored the relationship between pre-existing social status and salivary testosterone level among members of a rugby team at a Japanese university, where a strong seniority norm maintains hierarchical relationships. Participants played a series of one-shot Ultimatum Games (UG) both as proposer and responder. Opponents were anonymised but of known seniority. We analysed participants' acquiescence (how much more they offered beyond the lowest offer they would accept). The results showed that, among the most senior participants, higher testosterone was associated with lower acquiescence. Conversely, higher testosterone among the lower-status participants was associated with higher acquiescence. Our results suggest that testosterone may enhance socially dominant behaviour among high-status persons, but strategic submission to seniority among lower-status persons.

Observed and Normative Discount Functions in Addiction and other Diseases.

The aim of this paper is to find a suitable discount function able to describe the progression of a certain addiction or disease under treatment as a discounting process. In effect, a certain indicator related to a disease decays over time in a manner which is mathematically similar to the way in which discounting has been modeled. We analyze the discount functions observed in experiments which study addictive and other problematic behaviors as well as some alternative hyperbola-like discount functions in order to fit the patience exhibited by the subject after receiving the treatment. Additionally, it has been experimentally found that people with addiction display high rates of discount (impatience) and preference reversals (dynamic inconsistency). This excessive discounting must be correctly modeled by a suitable discount function, otherwise, it can become a trans-disease process underlying addiction and other disorders. The (generalized) exponentiated hyperbolic discount function is proposed to describe the progression of a disease with respect to the treatment, since it maintains the property of inconsistency by exhibiting a decreasing discount rate after an initial period in which the opposite occurs.

Can quantum approaches benefit biology of decision making?

Human decision making has recently been focused in the emerging fields of quantum decision theory and neuroeconomics. The former discipline utilizes mathematical formulations developed in quantum theory, while the latter combines behavioral economics and neurobiology. In this paper, the author speculates on possible future directions unifying the two approaches, by contrasting the roles of quantum theory in the birth of molecular biology of the gene.

A note on the roles of quantum and mechanical models in social biophysics.

Recent advances in the applications of quantum models into various disciplines such as cognitive science, social sciences, economics, and biology witnessed enormous achievements and possible future progress. In this paper, we propose one of the most promising directions in the applications of quantum models: the combination of quantum and mechanical models in social biophysics. The possible resulting discipline may be called as experimental quantum social biophysics and could foster our understandings of the relationships between the society and individuals.

Relationship between Salivary Oxytocin Levels and Generosity in Preschoolers.

This study examined the association between salivary oxytocin (sOT) levels and generosity in preschoolers. Fifty preschoolers played two dictator games (DG) by deciding how to allocate 10 chocolates between themselves and another child, who was either from the same class as the participant (ingroup member), or an unknown child from another class (outgroup member). sOT levels were assessed in saliva collected from the children immediately prior to the DG tasks. While sOT levels were negatively associated with allocations made to both ingroup and outgroup members by boys, among girl sOT levels were positively related to allocations made to ingroup members, and unrelated to allocations made to outgroup members. These results suggest sex differences in the association between salivary oxytocin and generosity.

Pharmacological and Expectancy Effects of a Low Amount of Alcohol Drinking on Outcome Valuation and Risk Perception in Males and Females.

The high-dose, alcohol-induced influences on risk perception and loss aversion depend on sex. On the other hand, low-dose alcohol has less effect on risky behavior. However, the effect of low-dose alcohol on subjective valuation of gain or loss and also the effect of placebo (expectancy of alcohol) on risk perception have not been fully investigated. We investigated the effects of low-dose alcohol (0.02 g/100 ml blood alcohol concentration) and placebo effects on subjective risk perception and subjective valuation of uncertain gain and loss in females and males. Participants in the control group and the placebo group were served alcohol-free, wine-flavored beverage and participants of alcohol group were served wine (14% alcohol). The placebo group was not informed that the drink was not alcohol but the control group was informed. Then paper-pencil tasks for subjective risk perception and valuation of gain or loss were performed 45 min after drinking the beverage. The participants were asked to draw the line on a 180 mm scale for each question. The placebo effects as well as the low-dose alcohol effects were observed in subjective valuations of gain or loss. Except for effect of beverages, a gender difference was also observed for subjective likelihood. The females estimated a low-probability loss as more likely and estimated a high-probability gain as less likely than did the males. From the Stevens' law fitting analysis, the placebo, not alcohol, significantly induced the psychophysical effect of the subjective valuation of gain or loss. These results indicate that the psychological effects of expectancy of alcohol (placebo) could be a major factor in changing the subjective valuation of gain or loss over the pharmacological effects of a small amount of alcohol (like a glass of wine). Furthermore, these results also indicate that gender differences should be taken into account when investigating pharmacological or psychological effect on decision-making.

Cross-cultural comparisons of delay discounting of gain and loss.

OBJECTIVES: People generally tend to discount future outcomes in favor of smaller but immediate gains (i.e., delay discounting). The present research examined cultural similarities and differences in delay discounting of gain and loss between Chinese and Japanese, based on a q-exponential model of intertemporal choice. METHOD: Using a hypothetical situation, we asked 65 Japanese participants and 51 Chinese participants to choose between receiving (or paying) a different amount of money immediately or with a specified delay (1 week, 2 weeks, 1 month, 6 months, 1 year, 5 years, and 25 years). For each delay, participants completed a series of 40 binary choices for gain or loss. RESULTS: Regardless of cultures, the q-exponential model was the optimal model. Both impulsivity and time-inconsistency were higher for future gains than for future losses. In addition to the cultural similarities, Chinese participants discounted future gains and losses more steeply than did Japanese. In contrast, Japanese participants were more time-inconsistent in delay discounting than were Chinese, suggesting that the reduction in their subjective value depended relatively on delay.

Reinforcement learning in depression: A review of computational research.

Despite being considered primarily a mood disorder, major depressive disorder (MDD) is characterized by cognitive and decision making deficits. Recent research has employed computational models of reinforcement learning (RL) to address these deficits. The computational approach has the advantage in making explicit predictions about learning and behavior, specifying the process parameters of RL, differentiating between model-free and model-based RL, and the computational model-based functional magnetic resonance imaging and electroencephalography. With these merits there has been an emerging field of computational psychiatry and here we review specific studies that focused on MDD. Considerable evidence suggests that MDD is associated with impaired brain signals of reward prediction error and expected value ('wanting'), decreased reward sensitivity ('liking') and/or learning (be it model-free or model-based), etc., although the causality remains unclear. These parameters may serve as valuable intermediate phenotypes of MDD, linking general clinical symptoms to underlying molecular dysfunctions. We believe future computational research at clinical, systems, and cellular/molecular/genetic levels will propel us toward a better understanding of the disease.

Changes of micro-RNAs in asymptomatic subjects sensitized to Japanese cedar pollen after prophylactic sublingual immunotherapy.

Japanese cedar pollinosis is the predominant seasonal allergic rhinitis in Japan, and it has increased in prevalence during the past 10 years. Sublingual immunotherapy (SLIT) is considered a safe and effective treatment for pollinosis. Micro-RNAs (miRNAs) are a class of short single-stranded RNA molecules that posttranscriptionally silence gene expression and may mediate allergic immune responses. The aim of this study was to investigate the miRNA alteration in asymptomatic subjects sensitized to Japanese cedar pollen under prophylactic SLIT under part of a randomized, double-blind, placebo-controlled, multiple-center trial. Analysis was undertaken in 15 asymptomatic subjects sensitized to Japanese cedar pollen-specific IgE (ImmunoCAP class ≥2) who participated in 2013. The SLIT group (n = 6) received standardized Japanese cedar pollen extract and the placebo group (n = 9) received an inactive placebo for 5 months covering the cedar pollen season. Changes in serum miRNAs were measured by real-time quantitative polymerase chain reaction to determine whether SLIT had effects on profiles of circulating miRNA. Seven subjects in the placebo group developed pollinosis symptoms, whereas no subjects in the SLIT group did (p = 0.007). Serum hsa-miR-223 was significantly up-regulated in postseason compared with preseason samples. The hsa-let-7b was significantly more down-regulated in postseason than in preseason samples from the placebo group; however, no significant differences were observed in those from the SLIT group. A significant decrease in circulating let-7b was also observed in the subjects who developed symptoms. Prophylactic SLIT was effective in preventing the development of pollinosis. Alterations in miRNA expression occurred in asymptomatic, sensitized subjects during cedar pollen season.

Activity in the left auditory cortex is associated with individual impulsivity in time discounting.

Impulsivity dictates individual decision-making behavior. Therefore, it can reflect consumption behavior and risk of addiction and thus underlies social activities as well. Neuroscience has been applied to explain social activities; however, the brain function controlling impulsivity has remained unclear. It is known that impulsivity is related to individual time perception, i.e., a person who perceives a certain physical time as being longer is impulsive. Here we show that activity of the left auditory cortex is related to individual impulsivity. Individual impulsivity was evaluated by a self-answered questionnaire in twelve healthy right-handed adults, and activities of the auditory cortices of bilateral hemispheres when listening to continuous tones were recorded by magnetoencephalography. Sustained activity of the left auditory cortex was significantly correlated to impulsivity, that is, larger sustained activity indicated stronger impulsivity. The results suggest that the left auditory cortex represent time perception, probably because the area is involved in speech perception, and that it represents impulsivity indirectly.

Neuroeconomics of psychopathy: risk taking in probability discounting of gain and loss predicts psychopathy.

BACKGROUND: This study investigated the relationships between psychopathy and impulsive and risky decision making, by utilizing intertemporal and probabilistic choices for both gain and loss, in addition to the Iowa gambling task. METHODS: The Psychopathic Personality Inventory-Revised - a 154-item measure that assesses psychopathic traits by self-report - was used with a 4-point response scale to assess 113 undergraduate students from three Japanese universities. Participants' performance on the Iowa Gambling Task and four behavioral neuroeconomic tasks of discounting - delayed gain, delayed loss, uncertain gain, and uncertain loss - were estimated. RESULTS: Risky decisions in probability discounting of gain and loss were associated with psychopathy. Psychopathic traits had no relationship with performance on the Iowa Gambling and were not significantly related to delay discounting. CONCLUSIONS: Psychopathy is predicted by risky decision in probability discounting of gain and loss, but not strongly associated with future myopia. Implications of the present findings for neuroeconomics and neurolaw are discussed.

Toward a physical theory of quantum cognition.

Recently, mathematical models based on quantum formalism have been developed in cognitive science. The target articles in this special issue of Topics in Cognitive Science clearly illustrate how quantum theoretical formalism can account for various aspects of human judgment and decision making in a quantitatively and mathematically rigorous manner. In this commentary, we show how future studies in quantum cognition and decision making should be developed to establish theoretical foundations based on physical theory, by introducing Taketani's three-stage theory of the development of science. Also, implications for neuroeconomics (another rapidly evolving approach to human judgment and decision making) are discussed.