In 2018, Japan introduced a plea bargaining system called “Japanese plea bargaining.” This system offers rewards for the provision of information about another person's crime. While the potential risk of false statements has been noted, there have been few actual cases, and a thorough examination has not been conducted. Therefore, this study conducted two experiments to examine the variables that influence the decision-making of those who are offered rewards for information. Experiment 1 demonstrated the impact of the informant's guilt or innocence on decision-making, with a higher acceptance rate reported in cases of guilt. Experiment 2 demonstrated the influence on decision-making of the association between the guilt or innocence of the informant and the degree of intimacy between the accused and the informant. In both experiments, when the informant was innocent, a certain number of offers were accepted, highlighting the likelihood of false statements and the associated risk of wrongful conviction in Japanese plea bargaining.

The Dark Triad is widely associated with antisocial behaviors. This study investigated whether the three facets of the Dark Triad prospectively predict psychological intimate partner violence (IPV) perpetration, and whether these effects are mediated by higher experiences of ostracism, an extra-relational factor. We focused on psychological IPV in romantic and marital relationships and conducted two three-wave longitudinal surveys over 6 months. We recruited 1,021 romantically involved individuals in Study 1 and 1,608 married individuals in Study 2. Across the studies, Machiavellianism, psychopathy, and narcissism at Time 1 were significantly positively correlated with psychological IPV perpetration at Time 3 respectively, and ostracism at Time 2 was significantly positively associated with psychological IPV perpetration at Time 3. Furthermore, the latent cross-lagged effects model indicated that Machiavellianism and psychopathy prospectively predicted psychological IPV perpetration at Time 3 through higher experiences of ostracism at Time 2 in both romantic and marital relationships. These results suggest the need for considering everyday experiences outside of intimate relationships for the prevention and intervention of IPV.

“Setsunasa” is one of the typical emotions in Japan and is an important concept that contributes to the construct of sadness. However, it remains unclear to what extent these two concepts are similar, and whether “setsunasa” possesses unique characteristics that distinguish it from sadness. This study examined the conceptual similarities and differences between sadness and setsunasa through three surveys. Study 1 employed features associated with sadness, and Study 2 used functional words related to sadness to investigate differences in ratings between sadness and setsunasa. Study 3 focused on actual emotional experiences, examining the intensity of emotions depending on the context, as well as their relationships with other emotional concepts and states related to sadness. The results of the three studies indicated that sadness and setsunasa share similarities but also exhibit notable differences. The findings suggest, furthermore, that sadness is predominantly characterized as a negative emotion, whereas setsunasa possesses qualities of a mixed emotion. Further investigation of setsunasa may elucidate the cultural characteristics of emotional experiences among the Japanese people.

This study aimed to develop a Japanese version of the Online Moral Disengagement Scale (J-OMD) and refine its reliability and validity. A total of 406 students, aged 15 to 18 years, participated in Study 1, which assessed structural validity, measurement invariance, internal consistency, and criterion-related validity of the translated scale. Confirmatory factor analysis indicated that, similar to the original English version, the J-OMD had a one-factor structure and demonstrated measurement invariance across genders. The scale exhibited strong internal consistency and criterion-related validity, showing positive correlations with traditional moral disengagement and internet trolling. Study 2 evaluated test-retest reliability over a 1-month interval with 157 of the participants. Test-retest reliability was moderate. These findings suggest that the J-OMD is a reliable and valid measure of online moral disengagement among Japanese students.

Police officers must strike a delicate balance between extracting crucial information from victims of sexual violence to solve cases and providing them with necessary psychological care. This study examined whether officers' self-perceptions of their attitudes during victim interviews aligned with victims' perceptions and investigated how these perceptions impacted the acquisition of essential information for case resolution. The current study analyzed 122 paired datasets comprising victims of sexual assaults and the corresponding police officers who interviewed them between October 2017 and December 2018. A categorical exploratory factor analysis identified a common factor, “appropriate attitude,” reflecting officers' concern for victims. A moderate intraclass correlation between the factor scores was found. The results from the actor-partner interdependence model indicated that victims who reported being properly cared for by officers were more likely to provide the details about their victimized experiences and influence officers' perceptions of whether they obtained essential information for their investigation, compared with those who did not report feeling cared for.

Stuttering is a speech disorder and adults who stutter (AWS) often suffer from psychological symptoms. Although psychological interventions have been implemented with AWS, qualitative and quantitative synthesis of the resulting evidence is lacking. Therefore, we conducted a systematic review and exploratory multilevel meta-analysis of psychological interventions for AWS. Twenty-four studies were included in the review, and data from the 13 selected studies were synthesized, from which the standardized mean difference in pre-post comparisons was appropriately estimated (n = 311, 85 effect sizes). Cognitive behavioral therapy (n = 191, 53 effect sizes) or mindfulness and/or acceptance interventions (n = 94, 22 effect sizes) were used with AWS in most of the synthesized studies. Overall, psychological interventions were efficacious in ameliorating psychological symptoms for AWS (ĝ = 0.63, 95% CI [0.49, 0.76]). Furthermore, significant interaction effects between outcome and intervention types were observed. We also found that effects of mental rehearsal, which was specifically developed in Japan, were explained by long intervention duration. Implications for psychological interventions for AWS are discussed.