Exchanges of group-based favours: Ingroup bias in the prisoner's dilemma game with minimal groups in Japan and New Zealand

Japanese ( N  = 48) and New Zealander ( N  = 55) participants were first assigned to one of two minimal groups, and then played a prisoner's dilemma game twice with an ingroup member and twice with an outgroup member. In one of the two games they played with an ingroup (or outgroup) member, participants and their partner knew one another's group memberships (mutual-knowledge condition). In the unilateral-knowledge condition, only the participants knew the group membership of their partner, but the partner did not know the group membership of the participant. Ingroup bias in cooperation emerged only in the mutual-knowledge condition in both countries; in the unilateral-knowledge condition no ingroup bias emerged. Mediational analyses found that, in accord with predictions, cooperation in the mutual-knowledge condition is mediated by expectation of the partner's cooperation. Ingroup bias in the mutual-knowledge condition emerged only among those who identified with the ingroup. Results provide support for a group heuristics account of ingroup favouritism in the minimal group. According to this account, participants who face minimal groups activate an ecologically adaptive heuristic of unilaterally cooperating with members of the same group, expecting indirect repayment from others in the same group.     

Spatiotemporal variations of alpha and sigma band EEG in the waking-sleeping transition period

The aim of this study is to evaluate the spatiotemporal variation of alpha and sigma band EEGs during the waking-sleeping transition or hypnagogic period. Power and coherence from 7 EEG channels (Fp1, F7, Fz, C3, Pz, T5, O1) were studied using EEG records of the period of 5 min. before the onset of Stage 1 to 24 min. after the onset of Stage 1. The EEG spectra were computed for 4 frequency bands (alpha 1: 8.0-9.0 Hz, alpha 2: 9.5-11.0 Hz, alpha 3: 11.5-12.5 Hz, and sigma: 13.0-15.0 Hz). The power of alpha 1 and 2 bands initially started to decrease before the onset of Stage 1. Principal component analysis of the coherence yielded Generalized and Localized Components in each band. The Generalized Component was widespread across scalp areas, while the Localized Component was a restricted local area. The Generalized Components of alpha 1 and 2 bands reached stable levels of NREM sleep about 1 min. after the onset of Stage 1. The component of sigma band reached a stable level of NREM sleep about 0.6 min. before the onset of Stage 2, while the component of alpha 3 band reached a stable level of NREM sleep about 3.4 min. after the onset of Stage 2. These results suggest that the alpha-sigma band EEG structures during the waking-sleeping transition period may not be uniform across EEG bands and that the hypnagogic EEG changes may start before the onset of Stage 1 and continue for several minutes after the onset of Stage 2.     

The Factor Structure of the Forms of Self-Criticising/Attacking & Self-Reassuring Scale in Thirteen Distinct Populations

There is considerable evidence that self-criticism plays a major role in the vulnerability to and recovery from psychopathology. Methods to measure this process, and its change over time, are therefore important for research in psychopathology and well-being. This study examined the factor structure of a widely used measure, the Forms of Self-Criticising/Attacking & Self-Reassuring Scale in thirteen nonclinical samples (N?=?7510) from twelve different countries: Australia (N?= 319), Canada (N?= 383), Switzerland (N?= 230), Israel (N?=?476), Italy (N?=?389), Japan (N?=?264), the Netherlands (N?=?360), Portugal (N?=?764), Slovakia (N?=?1326), Taiwan (N?=?417), the United Kingdom 1 (N?=?1570), the United Kingdom 2 (N?=?883), and USA (N?=?331). This study used more advanced analyses than prior reports: a bifactor item-response theory model, a two-tier item-response theory model, and a non-parametric item-response theory (Mokken) scale analysis. Although the original three-factor solution for the FSCRS (distinguishing between Inadequate-Self, Hated-Self, and Reassured-Self) had an acceptable fit, two-tier models, with two general factors (Self-criticism and Self-reassurance) demonstrated the best fit across all samples. This study provides preliminary evidence suggesting that this two-factor structure can be used in a range of nonclinical contexts across countries and cultures. Inadequate-Self and Hated-Self might not by distinct factors in nonclinical samples. Future work may benefit from distinguishing between self-correction versus shame-based self-criticism.     

Acquisition of the Meaning of the Word Orange Requires Understanding of the Meanings of Red,Pink, and Purple: Constructing a Lexicon as a Connected System

This research investigated how children build up the language-specific system of the color lexicon, examining factors that play important roles for the construction of an adult-like color lexicon. We had 3-, 4-, and 5-year-old Japanese-speaking children and adults (n = 20, 18, 19, and 19, respectively) produce names for 93 color swatches. The results showed that children of all ages were able to apply most of the chromatic words to the colors close to the center of each category, but even 5-year-olds struggle to delineate the boundaries between the words. Furthermore, the model analyses revealed that broad-covering and high-frequency words are mapped to the center of the lexical category earlier. However, cross-individual consistency in adults' use contributed most strongly for the adult-like boundary delineation. The results suggest that the process of system construction consists of at least two steps (i.e., mapping words to their category center and finding appropriate boundaries between neighboring words), with the quantity and the quality of the input contributing differently to the steps.