People are more likely to judge repeated information as true compared to new information. This so-called truth effect can be mainly attributed to the experienced fluency during the processing of repeated (vs. novel) information and is substantially moderated by the retention interval length between information presentations. In the present research, we systematically manipulated (a) the repetition status of the presented information and (b) the length of the retention interval between first exposure and the judgment phases within participants. During the judgment phases, we measured response times from the information onset until participants provided a binary judgment (“true” vs. “false”). This allowed us to analyze our data using a hierarchical diffusion modeling approach to estimate effects of repetition on specific cognitive processes during truth evaluations. Our results indicate that information repetition results in faster encoding and enhanced speed of information accumulation supporting the veracity of a statement – both of which are reduced with increased interval length.