ABSTRACT
The challenge arose out of attempts by Murdock and Kahana (1993a) to modify the Theory of Distributed Associative Memory or TODAM model (Murdock, 1982) to account for the absence of a list-strength effect (LSE) in recognition (Ratcliff, Clark, & Shiffrin, 1990). A LSE was said to have occurred when after some items on a list were strengthened (either by lengthening study time or through repeated study), retrieval of the nonstrengthened items was harmed. Although Ratcliff et al. (1990) found that a LSE occurred in free and cued recall, standard recognition failed to produce a LSE. In other words, strengthening some items did not adversely affect the probability of recognizing the nonstrengthened items. This was troubling as the global memory models (Search of Associative Memory or SAM-Gillund & Shiffrin, 1984; MINERVA 2-Hintzman, 1984; the Matrix model-Pike, 1984; Humphreys, Bain, & Pike, 1989; and TODAM-Murdock, 1982) predicted that a LSE would occur in both recognition and recall. Of these models, Shiffrin, Ratcliff, and Clark (1990) were able to modify only the SAM model to account for the differing effects of list strength on recognition and recall.
