We designed a Japanese version of the Smartphone Dependence Scale (J-SDS) for university students,
and assessed its validity and reliability. For development of this scale, we initially selected
43 preliminary items based on previous studies of Internet and mobile phone dependence. Each
response was scored using a Likert scale (0, 1, 2, 3), with higher scores indicating greater dependence.
After administering the preliminary scale to 149 university students, the final 29 items
were selected according to exploratory factor analysis. The final scale consisted of 5 factors: 1)
craving and withdrawal, 2) overuse and tolerance, 3) virtual life orientation, 4) disturbance of
concentration in class, and 5) physical symptoms. Reliability coefficient (Cronbach’s alpha) values
for the 5 factors and total J-SDS were 0.87, 0.87, 0.76, 0.77, 0.69, and 0.92, respectively. We then
summed the Likert scores for each item to provide a quantitative overall smartphone dependence
score, with higher scores indicating greater dependence. The J-SDS score became significantly
higher with longer hours of smartphone use (p < 0.001). Our results suggest that the J-SDS is a reliable
and valid scale for screening university students who may be at risk of developing smartphone
dependence.