The relationship between delay discounting and Internet addiction: A systematic review and meta-analysis

•Delay discounting can be used as an appropriate outcome to measure impulsivity in individuals with Internet addiction.•Judicious use of analysis methods is recommended.•The modes of administration need to be concerned.•The male predominance and task-related variables have significant impacts on discounting rate. To estimate the difference in delay discounting (DD) between subjects with Internet addiction (IA) and those without as well as to identify significant variables involved in DD. Using the keywords related to IA (e.g., “excessive Internet use”, “Internet dependence”) AND “delayed reward discounting” OR “delay discounting” OR “temporal discounting” OR “delayed gratification” OR time discounting OR intertemporal choice OR impulsive choice, the PubMed, Embase, and PsycINFO databases were searched from inception to June 2020 for English articles with comparison between subjects with IA and those without. Effect sizes were calculated by group means from the k value or area under the curve (AUC). The random-effects models were used. Fourteen studies in total were eligible for the current meta-analysis that involved 696 subjects with IA (mean age = 22.71) and 2,394 subjects without (mean age = 21.91). Subjects with IA had a steeper DD rate (g = 1.10, 95% CI: 0.57–1.64; p ≤ 0.01) compared with that in those without. Regarding DD data, the difference between k value and AUC was significant (p k). Additionally, the estimation of DD by the paper-and-pencil task was larger than that by the computerized task (p IA). The percentage of men and task variables were significantly associated with the DD rate (all p