A paired-associates list with 8 unique items and 8 confusable twinned stimuli, was administered to 50 Ss by the anticipation method. Responses were 5 common nouns, highly integrated and discriminable, and prelearned by Ss. Unique items were learned in an all-or-nothing fashion, but twin items were learned in 2 steps, association and stimulus discrimination, each of which was all-or-nothing. A discontinuous multiple-process model, based on strategy-selection theory, was shown to fit the data.