What does a person in a "TOT" state know that a person in a "don't know" state doesn't know

The purpose of this study was to examine the significance of Brown and McNeill's (1966) findings regarding the "tip of the tongue" (TOT) phenomenon, A modified version of their procedure was used with 56 Ss. Although their findings that Ss in a TOT state can detect parts and properties of the missing word were generally replicated, a division of the TOT state into a variety of substates showed correct detection rate to vary greatly, depending on the substate involved. In addition, correct detection of partial information was demonstrated even when S declared he had no knowledge of the selected word (don't know). It was suggested that a distinction be made between information detection based on knowledge of the characteristics common to the class of items of which the target is a member ("class detection") and detection based on knowledge of characteristics specific to the target in question ("differential detection"). Both class and differential detection were found to obtain in TOT states as well as in the don't know state. Some theoretical and methodological implications were suggested