How daily alternative behaviors' expected value shapes problematic smartphone use? An ecological momentary assessment...

With the global rise in smartphone use, problematic smartphone use (PSU) has emerged as a critical mental health concern. While reinforcement pathology theory posits that a high expected value of alternative behaviors (EVAB; e.g., psychological rewards from social or physical activities) may mitigate addictive tendencies, no prior study has examined this hypothesis in daily life contexts. This study is the first to investigate the within-person dynamics of EVAB on PSU and its underlying mechanisms. Using ecological momentary assessment (EMA), 72 participants (M_age = 19.01 ± 0.93 years; 40 females) completed baseline measures of episodic future thinking (EFT) followed by 14 days of intensive longitudinal data collection (three daily reports), assessing EVAB, delay discounting, PSU, and screen time. Dynamic structural equation modeling (DSEM) revealed two key findings: First, momentary increases in EVAB predicted subsequent reductions in both PSU levels and screen time, mediated by decreased delay discounting (β = -0.032, HPD 95 % CI = [-0.051, -0.014]). Second, individual differences in EFT detail/vividness and mental imagery positively predicted daily EVAB, which in turn reduced PSU via lower delay discounting (β = -0.015, HPD 95 % CI = [-0.026, -0.006]; β = -0.012, HPD 95 % CI = [-0.022, -0.004]). These results provide the first empirical support for core hypotheses of reinforcement pathology theory in PSU research, elucidating the dynamic role of EVAB while offering novel theoretical and clinical insights. The findings emphasize that PSU interventions should target both within-person fluctuations in reinforcement valuation and between-person differences in future-oriented cognition.