By combining a typical advice taking paradigm with a source monitoring task, the presented research investigates people’s ability to discriminate between their own self-generated initial estimates and advice from different advisor sources. In a laboratory experiment (N = 154), participants first provided their own calorie estimates for a number of different food items. Afterward, participants received advice on the calorie estimates from two different advisor sources of varying quality labeled as expert and lay advisors. Finally, participants completed a classic source monitoring task. In this task, participants indicated the source of the presented calorie estimates (own self-generated initial estimate, expert advisor estimate, lay advisor estimate or new estimate). Consistent with previous memory literature, the behavioral results indicate both better item and source memory for people's own self-generated initial estimate than for the external advice. However, using multinomial modeling that allows a separate measurement of memory and guessing processes, the modeling results reveal a complex guessing pattern. The presented work offers novel and fine-grained insights into the role of memory and guessing influences in advice taking.