Dual process theories conceive human thinking as an interplay between heuristic processes that operate automatically and analytic processes that demand cognitive effort. The interaction between these two types of processes is poorly understood. De Neys and Glumicic (2008) recently found that most of the time heuristic processes are successfully monitored. This monitoring, however, would not demand as many cognitive resources as the analytic thinking that is needed to solve reasoning problems. In the present study we tested the crucial assumption about the effortless nature of the monitoring process directly. Participants solved base-rate neglect problems in which heuristic and analytic processes cued a conflicting response or not. Half of the participants reasoned under a secondary task load. A surprise recall task was used as an implicit measure of whether the participants detected the conflict in the problems. Results showed that, even under load, base-rate recall performance was better for conflict problems than for no-conflict problems. Although participants made more reasoning errors under load, recall of the conflict problems was not affected by the working memory load. These findings support the claim about the successful and undemanding nature of the conflict detection process during thinking.