In a special issue of the Journal of Memory and Lan- guage devoted to research on memory illusions, Roedi- ger (1996) provided a historical overview of errors in perception and memory. He defined a memory illusion as an instance in which a person���s report of a past event seriously deviates from the actual event. One striking ex- ample offered as evidence of a memory illusion was Deese���s (1959) finding of false recall in a list-learning paradigm. Deese presented subjects with lists of seman- tic associates to nonpresented critical words. For exam- ple, for the critical word needle, the presented list con- sisted of thread, pin, eye, sewing, sharp, point, pricked, thimble, haystack, pain, hurt, and injection. When the subjects were given a free recall test after each list���s pre- sentation, the nonpresented critical word was often erro- neously recalled more frequently than nonpresented but unrelated words. This procedure induced subjects to re- call specific words that were never presented in the lists. Beginning with Roediger and McDermott (1995), there has been a revival of interest in this paradigm for study- ing this false memory effect (e.g., McDermott, 1996 Payne, Elie, Blackwell, & Neuschatz, 1996 Read, 1996 Schacter, Verfaellie, & Pradere, 1996). Roediger and McDermott (1995) reported two exper- iments that replicated and extended Deese���s (1959) re- sult. In their first experiment, the subjects were read six of Deese���s lists that elicited the highest frequency of false recall. After each list was presented, the subjects were given a free recall test, followed by a recognition test after all of the lists were recalled. The recognition test was composed of studied words, nonstudied critical words (hereafter referred to as ���critical lures���), and non- studied unrelated words. Roediger and McDermott found that the critical lures were falsely recalled and recog- nized more frequently than were other nonstudied words. In their second experiment, Roediger and McDermott (1995) modified their procedure. Half of the subjects re- ceived a free recall test after each study list presentation, and half performed unrelated math problems instead. On the subsequent recognition test, the researchers made use of Tulving���s (1985) remember versus know judgment task. For any recognized word, the subjects had to indi- cate whether they specifically remembered the word���s occurrence at study (a remember judgment) or they merely knew the word had been presented in the absence of any specific recollection (a know judgment). Roediger and McDermott found that the study and recall condition led to more false recognitions of critical lures than did the study and math condition. However, the subjects in both conditions produced false alarms to the critical lures at rates that were comparable to the corresponding hit rates for studied words. Moreover, the results showed that recognized critical lures were often characterized as remembered in the remember versus know judgment task, especially in the study and recall condition. These observations led Roediger and McDermott to describe the false recognition effect as a ���powerful illusion of memory��� (p. 803). This illusion is all the more surpris- ing, they said, because it was observed under intentional learning conditions, with short retention intervals, in a list- learning laboratory procedure that normally produces few errors, and with professional memorizers (college students) as subjects. The primary purpose of the present research was to de- termine whether subjects could avoid creating false mem- ories in Roediger and McDermott���s (1995) false recogni- tion paradigm if they were forewarned about this memory 271 Copyright 1997 Psychonomic Society, Inc. Appreciation is expressed to Chun Luo for helpful comments on an earlier draft of this paper. This research was supported by a Wesleyan Grant in Support of Scholarship made to J.G.S. Correspondence should be addressed to J. G. Seamon, Department of Psychology, Wesleyan University, Middletown, CT 06459-0408 (e-mail: jsea- mon@ wesleyan.edu). Remembering words not presented in lists: Can we avoid creating false memories? DAVID A. GALLO, MEREDITH J. ROBERTS, and JOHN G. SEAMON Wesleyan University, Middletown, Connecticut Can subjects avoid creating false memories as outlined in Roediger and McDermott���s (1995) false recognition paradigm if they are forewarned about this memory illusion? We presented subjects with semantically related word lists, followed by a recognition test. The test was composed of studied words, semantically related nonstudied words (critical lures), and unrelated nonstudied words. One group of subjects was uninformed about the false recognition effect, a second group was urged to minimize all false alarms, and a third group was forewarned about falsely recognizing critical lures. Compared with the uninformed and cautious subjects, the forewarned subjects reduced their false alarm rate for critical lures, and they made remember and know judgments equally often for recog- nized studied words and critical lures. But forewarning did not eliminate the false recognition effect, as these subjects and those in the other groups made numerous false recognitions in this task. Psychonomic Bulletin & Review 1997, 4 (2), 271���276

272 GALLO, ROBERTS, AND SEAMON illusion. To our knowledge, no one has specifically de- termined whether this false memory effect can be di- minished or eliminated by the subjects��� knowledge, but prior research has asked whether different experimental conditions can influence this effect. For example, Mc- Dermott (1996, Experiment 2) gave subjects multiple study and recall tests with the same word lists presented in either a blocked or a random manner. She found that random presentation produced less false recall than blocked presentation, but both forms of presentation still yielded false recalls after multiple study���test trials or a final recall test given 24 h later. Payne et al. (1996) ob- served a similar effect, showing that recognition of crit- ical lures did not decrease over a 24-h retention interval. Finally, Read (1996) manipulated encoding instructions by having subjects memorize word order or engage in elaborative or maintenance rehearsal during list presen- tation. He found that all three encoding conditions yielded high levels of false recall for critical words, but the false recalls were lowest for the subjects who focused on word order. These studies indicate that the false mem- ory effect persists through multiple study and test trials (McDermott, 1996), a 24-h delay between study and test (McDermott, 1996 Payne et al., 1996), and elaborative or maintenance rehearsal during encoding (Read, 1996). But false memory for critical words is diminished when the words are randomized over lists (McDermott, 1996) or the subjects attempt to memorize word order at study (Read, 1996). Following those studies, the present research sought to determine whether the false recognition of critical lures could be attenuated or eliminated by the use of fore- warning instructions. Curiously, we found no published research on the effects of foreknowledge on perceptual or memory illusions. For perceptual illusions, such re- search may have been unnecessary Gregory (1987) noted that these illusions occur even when people know that they are perceiving an illusion. For example, we may know that the lines in the M��ller-Lyer illusion are equal in length, yet one line still appears to be longer than the other. Perceptual illusions fool us because perceptual processes work extremely rapidly and do not take every- thing that we know into account in the process of form- ing a percept (Gregory, 1987). Memory illusions also fool us, but they do so over a more extended time frame that includes study and test conditions. Memory illu- sions may thus provide greater opportunity than percep- tual illusions to be influenced by the subject���s knowl- edge. To the extent that foreknowledge can be used during encoding or retrieval to devise compensatory cognitive strategies, an illusion may be diminished or eliminated. The only statements we found about the effects of foreknowledge on false memory are located in two places in Roediger and McDermott���s (1995) research. One state- ment suggests that forewarning might be effective in minimizing the false recognition of critical lures, whereas the other statement suggests little effect of forewarning. For example, the authors noted that they dropped the only subject from their analysis who had no false recalls of the critical words because at the end of Experiment 2, when the subjects were asked if they ���knew what the ex- periment was about,��� this subject reported that ���she no- ticed that the lists seemed designed to make her think of a nonpresented word��� (p. 808). This subject may have adopted a strategy that permitted her to overcome the memory illusion. However, Roediger and McDermott also reported that ���informal demonstration experiments with groups of sophisticated subjects, such as wily grad- uate students who knew we were trying to induce false memories��� still produced a strong false memory effect (p. 812). To the extent that these subjects were fully in- formed about this memory illusion before study, this ob- servation suggests that forewarning will have a minimal effect on the false recognition of critical words. The present research tested these foreknowledge al- ternatives systematically by comparing groups of sub- jects with different instructional sets in a modified ver- sion of the Roediger and McDermott (1996, Experiment 2) paradigm. To the extent that this false memory effect is a memory illusion that functions like a perceptual illu- sion, foreknowledge of the effect may have little or no ef- fect on the recognition of critical lures. But if this memory illusion differs from perceptual illusions in that it allows greater opportunity for performance to be influenced by encoding or retrieval strategies, foreknowledge of the il- lusion should attenuate the effect to the extent that peo- ple can devise effective compensatory strategies. We presented subjects with blocked lists of semantically re- lated words for study, followed by a recognition test after all lists were presented. One group of subjects was unin- formed about the false recognition effect, a second group was urged to be cautious at the time of the recognition test to minimize all false alarms, and a third group was fore- warned of the specific illusion by a demonstration and instructions before study. On the basis of Roediger and McDermott���s findings, we hypothesized that the subjects in the uninformed condition would produce a strong false recognition effect. Subjects in the cautious and fore- warned groups provide novel test conditions, and, com- pared with the uninformed condition, they should pro- duce either a comparable or a diminished effect. METHOD Subjects The subjects were 48 Wesleyan University undergraduates who served as paid volunteers. None had participated in any related mem- ory research. Materials We used 16 of Roediger and McDermott���s 24 word lists for study and test words (see their appendix). Each list was composed of 15 as- sociates to a nonpresented critical word (i.e., a critical lure). Within a list, the order of the words was constant and the strongest associates to the critical lure normally occurred first. For example, the list asso- ciated with the critical lure sleep consisted of the following words: bed, rest, awake, tired, dream, wake, snooze, blanket, doze, slumber, snore, nap, peace, yawn, and drowsy. For counterbalancing purposes, the 16 lists were divided into two sets of 8 lists, labeled A and B. Half