Psychonomic Bulletin & Review 2000, 7 (2), 354-359 Direct versus indirect tests ofmemory: Directed forgetting meets the generation effect COUN M. MAcLEOD and KAREN A. DANIELS University ofToronto, Scarborough, Ontario, Canada Subjects read 20 words and generated 20 others from defInitions during a 40-item study phase. Pro­ duction ofeach word was followed by an instruction to remember or to forget that word. In free recall, a direct test ofmemory, words that had been generated were recalled much betterthan words that had been read. The remember-forget instructional manipulation affected read words but not generated words. In speeded word reading, an indirect test of memory, all studied words showed priming, but read words showed more priming than generated words. Here, the effect of remember versus forget instructions appeared only for generated words. These dissociations ofa direct and an indirect test in­ dicate that two powerful encoding manipulations affect separable processes to which these tests are differentially sensitive. The prevalent lay view ofremembering rests on the con­ have come to be called priming effects. As reviewed by scious recollection ofpast episodes. Yet even over 100 years Richardson-Klavehn and Bjork, the combined evidence ago, in his ground-breaking empirical studies, Ebbinghaus from amnesic and normal subjects reveals a number of (1885/1964) distinguished two ways ofremembering: "in­ trends, of which we will highlight two. First, direct tests voluntary recollection" and "voluntary recollection." This generally are more influenced than are indirect tests by se­ distinction can be seen as a precursorto the current concepts mantic elaboration during encoding (Graf & Mandler, ofimplicit and explicit memory (Graf& Schacter, 1985), as 1984; Jacoby & Dallas, 1981), although exceptions do differentiated by two classes ofmemory tests. Indirect tests exist (Graf& Schacter, 1985). Second, a shift in modality reveal the influence ofmemory through facilitation ofper­ from study phase to test phase (e.g., from auditory to vi­ formance in the absence ofconscious recollection; in con­ sual) has little effect on direct measures yet sharply atten­ trast, direct tests require the conscious recollection ofpre­ uates priming on indirect measures (Bassili, Smith, & vious information. As illustrations, intentionally trying to MacLeod, 1989; Roediger & Blaxton, 1987), although ex­ recollect references that we wish to cite in an article consti­ ceptions exist here as well (Jacoby & Dallas, 1981). tutes a direct use of memory, whereas fluently using the It should be noted, however, that despite such strikingdis­ many features ofour word processors without realizing that sociations between direct and indirect tests, there also are memory is being tapped is an indirect use ofmemory. significant parallel effects. As illustrations, repetition of A variety ofdissociations in performance have been ob­ stimuli appears to facilitate performance on both types of served between direct and indirect tests, suggesting that test (Jacoby & Dallas, 1981; but see Challis & Sidhu, 1993), these two ways of using memory are quite different (see and same-context responses are significantly more effec­ Richardson-Klavehn & Bjork, 1988; Roediger & McDer­ tive than are different-context responses in aiding reten­ mott, 1993, for reviews). Studies of amnesia have made tion on both types oftest (Graf& Schacter, 1985). especially important contributions. Despite their frequently Roediger (1990) has offered a transfer-appropriate pro­ catastrophic failure on direct tests ofmemory, amnesics cessing account ofthe pattern ofresults seen on direct ver­ can show normal performance on indirect tests ofmemory sus indirect tests (see also MacLeod & Masson, 1997, in (Graf& Schacter, 1985; Graf, Shimamura,& Squire, 1985; press; Masson & MacLeod, 1992). Here, indirect tests are Warrington & Weiskrantz, 1970). These unconscious ef­ seen as relying on the fluent replaying ofthe encoding of fects in indirect tests-usually expressed as a benefit con­ stimuli, typically emphasizing perceptual components of ferred on subsequent processing by previous processing- their initial analysis. Direct tests typically rely more on any elaborative encoding done during study, emphasizing se­ mantic/conceptual processing that went beyond simply an­ alyzing the stimulus in context. Thus, a modality change This research was supported by Natural Sciences and Engineering Re­ search Council ofCanada Grant A7459, and formed the senior honors from study to test should disrupt recovery of the initial thesis ofK.A.D., who is now at the Georgia Institute ofTechnology. We perceptual analysis, affecting primarily indirect tests, thank Monica Ghosal and Shelley Hodder for their assistance in col­ whereas semantic elaboration at encoding should enhance lecting the data, and Barbara Basden, John Gardiner, Pierre Perruchet, conceptual processing, affecting primarily direct tests, as and Henry Roediger III, for their helpful comments during the review process. Correspondence should be addressed to C. M. MacLeod, Divi­ has been shown repeatedly.l sion of Life Sciences, University of Toronto, Scarborough, ON, MIC Our goal was to explore the direct-indirect test distinc­ IA4 Canada (e-mail: [email protected]). tion further by manipulating two powerful encoding vari- Copyright 2000 Psychonomic Society, Inc. 354 DIRECTED FORGETTING AND GENERATION 355 abies: directed forgetting and generation versus reading. that required subjects to provide words in response to de­ These variables are particularly ofinterest because they per­ finitions-presumably a more conceptual indirect test­ mit us to investigate the separate effects ofinitial percep­ although only under the item method. Thus, the most gen­ tual/conceptual encoding and of subsequent rehearsal on eral conclusion emerging now from the directed forgetting direct versus indirect tests. In what follows, we will con­ literature is that there ordinarily is not an R-F difference on sider the literature relating to each ofthese issues in tum indirect tests ofmemory, although as yet there are only a before describing in detail the purpose ofour study. few relevant studies. It also appears to be the case that in­ direct tests can be very sensitive to what otherwise might Directed Forgetting seem to be minor changes over experiments. Over the past 30 years, it has been well established that Two other points regarding directed forgetting studies stimuli accompanied by an instruction to forget ordinarily are especially relevant. First, as Basden et al. (1993) have show reduced retention relative to those accompanied by argued (see also MacLeod, 1998, 1999), the operative mech­ an instruction to remember (for recent reviews, see John­ anism in directed forgetting appears to differ as a function son, 1994; MacLeod, 1998). Known as directed forget­ of the method of delivery of the instructions. In the list ting, this phenomenon can be seen as a proper subset of method, F words appear to be encoded as well as R words, the more general phenomenon of intentional forgetting, but inhibited from retrieval. In contrast, in the item method, which spans social psychology, psychology and the law, F words appear to be rehearsed less and hence are not as animal cognition, and a variety ofother domains (see the well encoded. In our study, we used the item procedure recent book edited by Golding & MacLeod, 1998). Yet by because we wished to focus on directed forgetting due to far the majority ofthe directed forgetting work in the mem­ selective rehearsal. ory literature has exclusively examined performance on Second, in a study by Golding, Long, and MacLeod direct tests of memory, primarily recall and recognition. (1994) that examined recall only, we found that the ability It is worth noting at the outset that directed forgetting to forget information on cue was a function of the relat­ can be realized in either of two ways. Under the item edness ofstudied items. Subjects studied a list containing method, each individual item presented for study is as­ some semantically related successive words (e.g., crab­ signed its own instruction, usually displayed just after the leg) and some unrelated successive words (e.g., cheese­ item. Under the list method, a single instruction is pre­ fire, constructed from the related pairs cheese-cake and sented after each halfofthe list ofitems, with one halfof camp-fire). Using the item method, successive words the list to be forgotten and the other half to be remem­ sometimes received the same instruction, sometimes dif­ bered. The item method produces a larger remember­ ferent instructions. Although recall was best when both forget (R-F) difference than does the list method in both words in a pair were given a remember cue (i.e., the R-R recall and recognition; indeed, the list method generally condition), we also found good recall ofsemantically re­ does not produce a reliable R-F difference in recognition lated word pairs in the R-F condition, much better than (see, e.g., MacLeod, 1999). when the first word ofthe pair was an F word. We inter­ Does directed forgetting affect performance on indirect preted this finding as suggesting that compliance with an tests as well? The picture is not clear: The answer seems instruction to forget a word is difficult when that word im­ to depend both on the particular indirect test employed mediately follows an R word to which it is semantically and the method ofdelivering the instructions to