The effective sample comprised 261 college students. Participants completed a web survey using the Smartphone Addiction Scale-Short Version (measuring PSU), Social and Process Smartphone Use Scale, and Intolerance of Uncertainty Scale-Short Form. The survey was administered twice, with approximately one month separating two measurement waves. In this paper, the measures of intolerance of uncertainty and social/non-social smartphone use from Time 1 and the PSU score from Time 2 were used. Correlation analyses showed that intolerance of uncertainty and both social and non-social smartphone use are related to Time 2 levels of PSU.

In a structural equation model, intolerance of uncertainty was positively associated with non-social smartphone use, but not with social smartphone use. Non-social smartphone use was related to Time 2 PSU severity. Mediation analysis showed that only non-social smartphone use mediated the relationship between intolerance of uncertainty and levels of PSU. The study contributes to PSU research by demonstrating that intolerance of uncertainty and PSU are associated, and that non-social smartphone use may drive that relationship. This study emphasizes the need to understand the potential causes for excessive technology use.