The two-high-threshold (2HT) model of recognition memory assumes that people make memory errors because they fail to retrieve information from memory and make a guess, whereas the continuous unequal-variance (UV) model and the low-threshold (LT) model assume that people make memory errors because they retrieve misleading information from memory. We explored the nature of memory errors by comparing guessing and memory performance. In 2 experiments, participants studied lists of words followed by a test in which each trial was preceded by a cue indicating the probability that the trial would have a studied word. Participants first guessed whether or not the word would be studied, and then they saw the word and responded again. When the response that was more likely according to the cue was the correct response, participants made more errors after attempting to remember the word than in their initial guesses. This suggests that participants made errors because they retrieved misleading information even when they could guess the correct response on the basis of the probability cue. We also compared the models in terms of their ability to fit ROC functions using parametric bootstrap procedures to correct for model mimicry. These analyses supported both the UV and LT models over the 2HT model.