Frequency encoding of token and type information.

Two experiments examined how attention to stimulus attributes affects knowledge of frequency of occurrence. In Experiment 1, orienting tasks were used to direct subjects' attention to either the category membership or the initial letters of words. In Experiment 2, subjects' attention to words, category membership, and initial letters was directed with explicit instructions. The results of these two experiments suggest that attention to specific stimulus attributes may be necessary to initiate the encoding of frequency information. We discuss the implications of these results for claims that the encoding of frequency of occurrence is automatic.