Functional assessment of hikikomori behaviors: Functional types and psycho-behavioral factors.

Hikikomori is a condition of prolonged social withdrawal (at least six months) characterized by not working or attending school, not socializing outside one's home, and staying at home on most days except for solitary outings. Currently, there are no adequate tools for the assessment of individual differences in hikikomori functions. This study involved the development of the Hikikomori Functional Assessment Scale (HFAS), which quantitatively assesses the perceived functions of hikikomori. Three data samples were collected at different time periods and included 490 participants with hikikomori and 251 without hikikomori. An item pool was analyzed resulting in 17 items and three factors: intrapersonal-positive (pursuing activities and self-stimulatory behaviors), intrapersonal-negative (alleviating discomfort), and social-negative (avoiding social interactions) reinforcement. The HFAS showed good internal consistency reliability, moderate-to-good test-retest reliability, acceptable construct validity, and good criterion-related validity. Furthermore, social-negative reinforcement correlated positively with measures of depressive symptoms and subjective social functioning impairment and negatively with adaptive behavior and quality of life. Intrapersonal-negative reinforcement was weakly correlated with most of the related scales, and intrapersonal-positive reinforcement showed no significant correlations. Future studies are needed to confirm the consistency of functional assessment results with those of the HFAS, using behavioral observations by researchers and clinicians, and follow the changes in hikikomori functioning longitudinally.