Participants in this study were not reading under normal screening conditions. It may be that their alertness, concentration, and decision thresholds were affected by the knowledge that this study was a controlled laboratory experiment in which their decisions would be recorded and used in a study, and that the balance between cancer and normal cases was artificial. Because their assessments of the mammographic cases in this retrospective observer study would not affect patient care, their decisions could be different from those in an actual clinical setting. This effect has been described, among others, by Gur et al. [25]. However, the reading conditions in the with-CAD and without-CAD sessions were similar, and therefore the observed effect on detection performance can be attributed solely to the use of the interactive CAD system. Because we performed LROC analysis, decision thresholds did not affect study results.