Taiki Takahashi, Masters student Tokuda Shinsukue and others published a new paper in PloS one

Tsurugizawa, T.,Tokuda, S., Harada, T., Takahashi, T., & Sadato, N. (2016). Pharmacological and expectancy effects of a low amount of alcohol drinking on outcome valuation and risk perception in males and females. PloS one, 11, 4, e0154083.


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.

PDF paper download here: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0154083

Ph.D. program graduate Yoko Kitakaji and Associate Professor Susumu Onuma published a book chapter

Kitakaji, Y., Onuma, S. (2016). Even Unreliable Information Disclosure Makes People Cooperate in a Social Dilemma: Development of the “Industrial Waste Illegal Dumping Game”. In Kaneda, T., Kanegae, H., Toyoda, Y., & Rizzi, P., Simulation and Gaming in the Network Society, Springer, pp. 369-385.


This study explores whether information disclosure can cause cooperation in a social dilemma, even when people can disseminate false information. In the past, illegal dumping increased in Japan despite the strengthening of penalties and surveillance laws, due to practical limitations in monitoring and surveillance. To resolve this, the tracking sheet used to trace the trading and processing of the waste must be traceable, in order to detect illegal dumping. This means that manifests must be written precisely in order to be effective, but if maintaining a tracking log has some function other than surveillance, this may not be the case. To examine this issue, we used the “Industrial Waste Illegal Dumping game” (Ohnuma S, Kitakaji Y. Simure-syon ando geimingu (Stud Simul Gaming) 17(1):5–16, 2007) which simulates the disposal of industrial waste and is structured as a social dilemma with asymmetry of information. In this study we utilized two conditions: a disclosure and a control (need not disclose) condition. Under the disclosure condition, players had to enter the amount of commission or disposal in the landfill but did not have to fill in the correct amount. Although other players could read the report, they did not know who performed illegal dumping or how much they contributed. Therefore, this disclosure did not have an effective surveillance function and could not help detect noncooperation. However, the results showed that the amount of illegal dumping was reduced, and information about payoffs was actually shared more in the disclosure condition than in the control condition. Moreover, players collected and shared their information more in the disclosure condition than in the control condition. The study thus indicates that the function of disclosure is not surveillance, but information sharing which is essential for voluntary cooperation.

Chapter download link: http://link.springer.com/chapter/10.1007/978-981-10-0575-6_26

Assoc. Prof. Taiki Takahashi and others published a new paper in Proceedings of ECCS 2014

Mori, S., Hino, M., Hisakado, M., & Takahashi, T. (2015). Detection of Non-self-correcting Nature of Information Cascade. Proceedings of ECCS 2014, Springer International Publishing, 1-10.


We propose a method of detecting non-self-correcting information cascades in experiments in which subjects choose an option sequentially by observing the choices of previous subjects. The method uses the correlation function C(t) between the first and the t+1-th subject’s choices. C(t) measures the strength of the domino effect, and the limit value climtC(t) determines whether the domino effect lasts forever (c>0) or not (c=0). The condition c>0 is an adequate condition for a non-self-correcting system, and the probability that the majority’s choice remains wrong in the limit t is positive. We apply the method to data from two experiments in which T subjects answered two-choice questions: (i) general knowledge questions (Tavg=60) and (ii) urn-choice questions (T=63). We find c>0 for difficult questions in (i) and all cases in (ii), and the systems are not self-correcting.

PDF paper download here: https://arxiv.org/abs/1507.07265