There are two types of errors made in feeling-of-knowing (FOK) studies: a commission error occurs when a subject answers a question incorrectly, and an omission error occurs when a subject fails to provide an answer for a given question. A subject makes a commission error if he or she responds to the following question, "In which city does the Cotton Bowl take place?" with the response "Houston." If a subject responded, "I don't know," that would be an error of omission. Similar studies imply that the FOK distribution properties of both of these types of errors are the same. In two studies at separate universities, the FOK for errors of commission and omission were conducted. In both, the FOK rank order was reliably higher for errors of commission, in spite of the fact that subjects were informed that the items they were judging were answered incorrectly. These results suggest that the type of error made during recall is an important parameter in the feeling of knowing and that type of error may also add validity to subsequent tests of recognition memory for non-recalled items. (CM)