In signal detection theory (SDT), sensitivity measure d′ is popular, but its usages presuppose a equal-variance Gaussian model. This study showed that the value d′, which is estimated by the well-known formula, d′=Z(H)-Z(F), is strongly affected by the value of variance of sensation of a signal stimulus. That is, d′ is an inadequate sensitivity measure when the equal-variance Gaussian model does not hold. Hence, estimation of variance of a signal stimulus is prerequisite for SDT. It was shown by simulation that experimental estimations of the mean and variance of a signal stimulus were overestimated for 1AFC rating tasks, when category boundaries were not separated far enough. Overestimations were more salient for 1AFC yes/no tasks than for 1AFC rating tasks.

Recently, researchers in various fields such as anthropology, archaeology, history, neuroscience, and psychology have been collaborating on research projects to understand how civilizations were built. The purpose of this project is to reconstruct the past by integrating the findings in archaeology and those on human cognition and behavior. In this study, we are developing a cognitive map that indicates regional differences in human perception. Topic modeling for the abstracts of the Stroop test with the regions of author affiliations revealed that the topic proportions related to the task were high in North-Central America. In contrast, the topic proportions related to clinical research were high in Europe. Moreover, a meta-analysis using regions as a moderator showed that the effect sizes of the Stroop test were larger in Asia than those in Europe and North America. These results indicate regional differences in human executive functions. The relevance of human cognition to the distribution of tools, myths, and folk tales that have been created by people to date will be discussed.

Human uniqueness is often attributed to highly sophisticated cognitive ability. Through comparative studies with humans and non-human animals, especially our closest evolutionary relatives, behaviors not demonstrated by any non-human animals are considered unique to humans, and this inaction is then explained as arising due to a lack of necessary background cognitive abilities. However, even if non-human animals do not demonstrate a certain behavior, it is too early to say they cannot. There has been accumulating evidence that non-human animals do have the necessary cognitive bases for certain complex behaviors, yet still do not perform these in their everyday lives. By introducing some examples of chimpanzees’ social and cultural behaviors, I propose four hypotheses to explain their inaction, three of which are more focused on motivational than cognitive restrictions. This paper mainly discusses, from a motivational perspective, why certain behaviors do not manifest themselves despite evidence for their cognitive foundations.

Ethnoarchaeological research can elucidate the relationship between the body, objects, and technology and is expected to become increasingly important in future archaeology. This paper presents findings from continuous research on pottery production and individual potters in a pottery village in Thailand. A quantitative analysis of pottery sizes and shapes and motion analysis of the potters were conducted. The results show that skilled potters maintain stable movements in the long term. This indicates one aspect of the nature of motor habits, which were developed through long-term repetitive training. The findings also reveal the acquisition process of motor habits, social and individual learning in pottery making, unintentional mutual imitation, and interaction between humans and tools. These results are based on archaeological and anthropological perspectives; however, the findings are also relevant to the field of psychology.

Synesthesia is a phenomenon in which sensory inputs trigger additional percepts or cognitive processes. This article outlines a method to conduct psychological experiments with synesthetes. However, synesthesia is a subjective conscious experience possessed by only a small percentage of people, therefore, various difficulties arise when treating synesthesia as a subject of empirical psychological research. Consequently, we introduce definitions of synesthesia and the methods of objective measurement of synesthesia in psychological research proposed in previous studies. We further discuss various individual differences among synesthetes.

This note is a short report on the activities of the Young Researchers Committee of the Japanese Psychonomic Society (JPS). As the highlighted activity of the committee, we have held the oral session of the annual meeting of JPS both face-to-face and online formats nine times. We also have promoted interactive activities across the country through social networking services. By introducing public applications, we have tried to organize our committee with diverse members. We will continue to develop new activities to target a broader range of young or early-career researchers.

The Japanese Psychonomic Society Research Committee for Developing Teaching Materials was founded in 2012 to respond to social needs such as the promotion of science education. Researchers in various fields including psychology, education, and Virtual Reality have gathered to develop teaching materials of psychology using interactive technology. As a major topic in recent years, psychology will be introduced into the Public and Ethics in the subject area of Civics in high schools from the 2022 academic year, and there is an increasing need for methodologies to understand the relationship with society as one’s own affair. Therefore, this research committee planned a lecture titled “The Future of Psychology, Ethics, and Technology” at the 41st Annual Meeting of the Japanese Psychonomic Society, and discussed the connection between psychology and ethics in education and the impact of recent digital technology on psychology and ethics.