Kawaii (a Japanese word meaning “cute”) things are popular because they produce positive feelings. However, their effect on behavior remains unclear. In this study, three experiments were conducted to examine the effects of viewing cute images on subsequent task performance. In the first experiment, university students performed a fine motor dexterity task before and after viewing images of baby or adult animals. Performance indexed by the number of successful trials increased after viewing cute images (puppies and kittens; M ± SE = 43.9±10.3% improvement) more than after viewing images that were less cute (dogs and cats; 11.9±5.5% improvement). In the second experiment, this finding was replicated by using a non-motor visual search task. Performance improved more after viewing cute images (15.7±2.2% improvement) than after viewing less cute images (1.4±2.1% improvement). Viewing images of pleasant foods was ineffective in improving performance (1.2±2.1%). In the third experiment, participants performed a global–local letter task after viewing images of baby animals, adult animals, and neutral objects. In general, global features were processed faster than local features. However, this global precedence effect was reduced after viewing cute images. Results show that participants performed tasks requiring focused attention more carefully after viewing cute images. This is interpreted as the result of a narrowed attentional focus induced by the cuteness-triggered positive emotion that is associated with approach motivation and the tendency toward systematic processing. For future applications, cute objects may be used as an emotion elicitor to induce careful behavioral tendencies in specific situations, such as driving and office work.

According to sociometer theory, self-esteem serves as a barometer of the extent to which individuals are socially included or excluded by others. We hypothesized that trait self-esteem would be related to social pain responsiveness, and we used functional magnetic resonance imaging to experimentally investigate this potential relationship. Participants ( n = 26) performed a cyberball task, a computerized game of catch during which the participants were excluded from the game. Participants then rated the degree of social pain experienced during both inclusion in and exclusion from the game. Individuals with lower trait self-esteem reported increased social pain relative to individuals with higher trait self-esteem, and such individuals also demonstrated a greater degree of dorsal anterior cingulate cortex activation. A psychophysiological interaction analysis revealed a positive connectivity between the dorsal anterior cingulate and prefrontal cortices for the lower trait self-esteem group, and a corresponding negative connectivity for the higher trait self-esteem group. Heightened dorsal anterior cortex activity and a corresponding connection with the prefrontal cortex might be one possible explanation for the greater levels of social pain observed experienced by individuals with low trait self-esteem.

The relationship between memory enhancement and fast (13–16 Hz) versus slow (10–13 Hz) spindle activity during sleep was investigated. Standard polysomnographic recordings were conducted during an adaptation, control nonlearning, and learning night. Automatic spindle detection and measurement was utilized with visual confirmation. Participants slept in individual, temperature-controlled bedrooms in a sleep laboratory. Twelve healthy student volunteers (9 women and 3 men, mean age: 22.3 years) participated. On the learning night, participants completed a presleep learning session on a modified version of mirror-tracing task followed by a postsleep test session. No learning or test sessions were performed on the adaptation and nonlearning nights. Tracing time was reduced by 6.4 seconds (20.6% ± 2.07%) from the presleep to the postsleep session. Mean amplitude and duration of fast spindles was greater on the learning night than on the nonlearning night (both P values < 0.05). Skill improvement and fast-spindle activity were positively correlated (density [r = 0.76, P < 0.01 ], amplitude [r = 0.69, P < 0.05], and duration [r = 0.67, P < 0.05]). Significant correlations between fast-spindle activity and mirror-tracing performance were also evident for the nonlearning night. There was no significant relationship between mirror-tracing performance and slow-spindle activity on any night. The thalamocortical network underlying fast-spindle generation may contribute to or reflect plasticity during sleep.

People feel psychological pain when they are excluded, and this pain is often attenuated when emotional support is received. It is therefore likely that a specific neural mechanism underlies the detection of social exclusion. Similarly, specific neural mechanisms may underlie the beneficial effects of emotional support. Although neuroimaging researchers have recently examined the neural basis of social pain, there is presently no agreement as to which part of the anterior cingulate cortex (ACC) is involved in the perception and modulation of social pain. We hypothesized that activity in those brain regions that are associated with social pain would be correlated with decrements in social pain induced by emotional support. To examine the effects of emotional support on social pain caused by exclusion, we conducted an fMRI study in which participants played a virtual ball-tossing game. Participants were initially included and later excluded from the game. In the latter half of the session from which participants were excluded, participants received emotionally supportive text messages. We found that emotional support led to increased activity in the left lateral/medial prefrontal cortices and some temporal regions. Those individuals who experienced greater attenuation of social pain exhibited lower ventral ACC and higher left lateral prefrontal cortex activation. These results suggest that the ventral ACC underlies social pain, and that emotional support enhances prefrontal cortex activity, which in turn may lead to a weakened affective response.

‘Kawaii’ is one of the most popular words in contemporary Japan and is recognized as representative of Japanese pop culture. It is often translated into English as ‘cute’, but a subtle difference of nuance seems to exist between the two words. In this article, a framework for research on kawaii from a behavioural science perspective is put forward. After introducing the dictionary definition, history and current usage of kawaii, this article reports survey results of Japanese students and office workers about their attitudes towards kawaii. These findings and past psychological and behavioural science research lead to a two-layer model that consists of kawaii as an emotion and kawaii as a social value. This model postulates that the basis of kawaii is a positive emotion related to the social motivation of watching for and staying with preferable persons and objects, which is typically observed in affection towards babies and infants, but not limited to them. This culturally non-specific, biological trait has been appreciated and fostered in Japan by certain characteristics of Japanese culture. Because previous research on cuteness has been almost exclusively associated with infant physical attractiveness and baby schema, using the relatively fresh, exotic word ‘kawaii’ may be helpful to describe this broader psychological concept.

The present study examined the first-night effect during the sleep-onset period using the 9 electroencephalogram stage scoring system. After a week of monitoring sleep-wake habits with sleep diaries and wrist actigraphy, polysomnography recording was made for 3 consecutive nights. Participants slept in their own private, individual, temperature-controlled bedroom in a sleep laboratory at the university. Eleven healthy student volunteers (5 women and 6 men, 21 to 25 years old, mean 22.7 years) who had no experience sleeping in a laboratory participated in the study. N/A The electroencephalogram during the sleeponset period was scored manually for every 5-second epoch into 9 electroencephalogram stages. Latencies of the electroencephalogram stages were delayed on the first night, especially during the alpha-wave intermittent stages. The average time of the alpha-wave train, intermittent (> 50%) and the electroencephalogram flattening stage increased on Night 1. Stage changes among these stages also increased on Night 1. In contrast, stage changes between the alpha-wave intermittent stage (< 50%) and the thetawave stage increased on Night 3. Alpha-wave activity increased on Night 1, demonstrating that the activity of the wake-promoting system during the sleep-onset period was enhanced on the first night. From the second to the third night, the alpha-wave intermittent stage jumped to the theta-wave stage, omitting electroencephalogram flattening, suggesting that the electroencephalogram flattening stage is unlikely to appear during stable sleep-onset period. This is the first study to demonstrate the detail of the first-night effect during the sleep-onset period.