In recent years, "lying flat" has been enthusiastically pursued by young people in China, and it is worth studying its cause and social impact. However, there is still a lack of measurement tools that can scientifically evaluate an individual's tendency for "lying flat." In this study, a 6-item "Lying Flat" Tendency Scale was developed and cross-validated for reliability and validity in different samples from China. The findings demonstrated that the scale showed good internal consistency in three different samples; both exploratory factor analysis and confirmatory factor analysis supported the single dimension model of the scale, indicating good construct validity; the LFTS total score was negatively correlated with the satisfaction of basic psychological needs, happiness index, and positive emotions, and was positively correlated with negative emotions; simultaneously, the LFTS total score was also significantly positively correlated with the choice of "lying flat" behavior in the simulated situation. These results show that the scale has good validity and reliability, and can be used as a measuring tool for subsequent empirical research. It will help to promote the development of empirical research on the phenomenon of "lying flat", help to understand the causes and consequences of "lying flat" more deeply, and also help to find effective ways to help young people break out of the "lying flat" dilemma.
Keywords: reliability; scale development; validity; “lying flat”.