Development and validation of a plateau experience psychometric to investigate the effect of shinrin-yoku on depression

A proposed direction for transpersonal psychology is the development of empirical research within the field, specifically in assessing the effects of transpersonal practices. The areas of self-actualisation, peak experience and flow have been subjected to research predominantly using psychometrics, however a range of theoretical and methodological issues within these concepts are evident. An alternate concept for future research was advocated by Maslow through his concept of self-transcendence, characterised by the plateau experience, yet in the past forty years, this concept has remained relatively obscure. This paper advocates further research into the plateau experience, through initially defining the concept, progressing to discuss the development of a plateau experience psychometric (PLEX), and using the PLEX within a validation study investigating the effects of shinrin-yoku (forest air breathing/bathing).