<P> Retroactive interference (RI) is a phenomenon that occurs when newly learned information interferes with and impedes the recall of previously learned information . RI is a result of decreased recall of the primary studied functions due to the learning and recall of succeeding functions . RI is a classic paradigm that was first officially termed by Muller . These memory research pioneers demonstrated that filling the retention interval (defined as the amount of time that occurs between the initial learning stage and the memory recall stage) with tasks and material caused significant interference effects with the primary learned items . </P> <P> As compared to proactive interference, retroactive interference may have larger effects because of the fact that there is not only competition involved, but also unlearning . </P> <P> Briggs (1954) study modeled McGeoch's work on interference by setting the stage for a classic design of retroactive interference . In his study participants were asked to learn 12 paired associates to a criterion of 100% . To ensure parsimony, these pairs can be labeled as A-B -, A-B -...A-B (also called AB / AC paradigm). Briggs used a "modified free recall" technique by asking participants to recall an item when cued with B. Over multiple anticipation trials, participants learned B items through the prompt of B items . After perfecting Ai - B learning, participants were given a new list of paired associates to learn; however B items were replaced with C items (now given a list of A-C -, A-C -...A-C). As the learning of A-C pairs increased, the learning of A-B pairs decreased . Eventually recalling the Ci items exceeded the recall of the B items, representing the phenomenon of retroactive interference . A significant part of Briggs (1954) study was that once participants were tested after a delay of 24 hours the Bi responses spontaneously recovered and exceeded the recall of the Ci items . Briggs explained the spontaneous recovery illustration as an account of A-B items competing with A-C items or, as McGeoch would define it: "a resultant (of) momentary dominance". </P> <P> J.M. Barnes and B.J. Underwood (1959) expanded Briggs (1954) study by implementing a similar procedure . The main difference in this study, however, was that unlike Briggs (1954) "modified free recall" (MFR) task where participants gave one item responses, Barnes and Underwood asked participants to give both List 1 and List 2 responses to each cued recall task . Participants' ability to recall both items was termed "modified modified free recall" (MMFR) technique . Equivocally to Briggs (1954) results, RI occurred when C recalled responses gradually came to exceed B responses . Barnes and Underwood argued that because there was "unlimited recall time" to produce multiple item responses, the fact that A-C responses still trumped A-B responses represented an account of unlearning . </P>

Define the distinction between proactive and retroactive interference