1. References McDermott, K.B. (1996). The persistence of false memories in list recall. Journal of Memory and Language, 35, 212-230. Miller, M.B., & Wolford, G.L. (1999). Theoretical Commentary: the role of criterion shift in false memory. Psychological Review, 106, 398-405. Nelson, D.L., McEvoy, C.L., & Schreiber, T.A. (1998). The University of South Florida word association, rhyme, and word fragment norms. http://w3.usf.edu/FreeAssociation/ Schacter, D.L., Israel, L., & Racine, C. (1999). Suppressing false recognition in younger and older adults: The distinctiveness heuristic. Journal of Memory and Language, 40, 1-24. Stretch, V., & Wixted, J.T. (1998). On the difference between strength- based and frequency-based mirror effects in recognition memory. Journal of Experimental Psychology: Learning, Memory, and Cognition, 18, 681-690. Toglia, M.P., Neuschatz, J.S., & Goodwin, K.A. (1999). Recall accuracy and illusory memories: When less is more. Memory, 7, 233-256. Wickens, T.D., & Hirshman, E. (2000). False memories and statistical decision theory: Comment on Miller and Wolford (1999) and Roediger and McDermott (1999). Psychological Review, 107, 377-383. Wixted, J.T., & Stretch, V. (2000). The case against a criterion-shift account of false memory. Psychological Review, 107, 368-376. Experiment 1 Predictions  Decision-based model  False recognition should be affected by blocking in pure lists, but not mixed lists  Memory-based model  False recognition should be affected by blocking in both pure and mixed lists equally The Effect of Blocking Study List Presentation on False Recognition Jason Arndt & Karen Lee (Correspondence to jarndt@middlebury.edu) Middlebury College Abstract Two experiments examined the effect of presenting study items blocked by theme or with themes randomly intermixed on semantic false recognition. In the first experiment, we examined the influence of manipulating this variable within and between lists. In our second experiment, we collected recognition memory confidence ratings. In Experiment 1, true and false recognition levels were higher in the blocked condition in pure lists, but not mixed lists. In Experiment 2, ROC analyses suggested that levels of memory strength supporting false recognition were greater when themes were presented blocked. While the results of Experiment 1 can be explained by decision- based theories of false recognition, the results of Experiment 2 are beyond the scope of pure decision-based explanations, and necessitate the appeal to memory-based mechanisms. Conclusions  Differential pattern of false recognition across pure and mixed lists is consistent with decision-based accounts of false recognition (e.g., Miller & Wolford, 1999; Schacter, et al., 1999)  Differential pattern of hits across pure and mixed lists suggests ambiguity between memory- and decision-based explanations  ROC analyses consistent with memory-based explanation, and inconsistent with decision-based explanation (e.g., Wickens & Hirshman, 2000; Wixted & Stretch, 2000)  Results support prior reports (McDermott, 1996; Toglia, Neuschatz, & Goodwin, 1999) that blocking leads to greater memory strength for studied and lure items. However, this generality may not extend to cases where blocking is manipulated within study lists. Experiment 2 Predictions Decision-Based Model Memory-Based Model Confidence Ratings Memory ModelDecision Model Random Criteria Blocked Criteria Experiment 1 HitsLure False Alarms Experiment 2 Old vs. NewLures d a Blocked: 1.47 Random: 1.28 d a Blocked: 0.74 Random: 0.52 Theoretical Background  Decision-based models propose that false recognition levels change because participants alter the level of information required to endorse test items as studied (e.g., Hirshman, 1995; Miller & Wolford, 1999).  Memory-based models propose that false recognition levels change because the level of evidence in memory for unstudied items is affected by study conditions (e.g., Wickens & Hirshman, 2000; Wixted & Stretch, 2000). Within- vs. Between-List Designs  Decision-based and memory-based theories of false recognition can be evaluated by comparing the effects of an independent variable across within- and between-list manipulations of a variable (Schacter, et al., 1999).  Participants are free to adopt different decision strategies across conditions in a between-lists design.  Participants maintain a single decision strategy across conditions in within-lists designs (Stretch & Wixted, 1998).  Therefore, if false recognition differs across conditions in a between-lists design, but those differences are not evident when the same conditions are manipulated within lists, decision-based models are supported.  Memory-based models propose that false recognition is caused by the properties of encoded memory representations.  Memory-based models expect that false recognition differences should replicate across the two designs. Experiment 1 (N = 32)  Materials: 96 sets of ten items (referred to as themes henceforth) from Nelson, McEvoy, and Schreiber (1998)  All items in a given theme produced a single item (the lure item) in free association with a nonzero probability  Theme items:chirp, sparrow, bluejay, canary, feathers, nest, pigeon, robin, parrot, pelican  Lure item: bird  Four study lists, each study list composed of 12 themes  Blocking manipulated within subjects  Blocked themes: theme items presented in immediate succession  Random themes: theme items intermixed with other themes  List Composition manipulated within subjects  Pure lists contained themes presented all in blocked or random format  Mixed lists contained 6 themes presented blocked and 6 themes randomly intermixed with one another  Test lists composed of studied items, lures associated with studied items, a comparable set of unstudied theme items, and lure items related to unstudied themes Experiment 2 (N = 72)  Blocking manipulated within subjects, but only in pure lists  Participants asked to provide confidence ratings (1 = positive old; 6 = positive new) for each test item judgment  Test lists composed of studied items, lures associated with studied items, a comparable set of unstudied theme items, and lure items related to unstudied themes Models and Confidence Ratings  Decision-based model  Evidence in memory for lures same across blocked and random presentation lists  Confidence ratings produced by two sets of criteria (one for random lists, one for blocked lists)  Memory-based model  Blocked presentation produces a greater increment in evidence for lures than random presentation  Confidence ratings produced by a single set of criteria