The Role of Decision Processes in Conscious Recollection

Dual-process models of recognition memory posit a rapid retrieval process that produces a general sense of familiarity and a slower retrieval process that produces conscious recollections of prior experience. The remember/know paradigm has been used to study the subjective correlates of these two processes, with remember judgments assumed to index conscious recollection and know judgments assumed to index familiarity. Recently, a two-criterion signal detection model has been proposed as an alternative account of this paradigm. This model assumes only a single memory process with a criterion separating remember from know responses. This report presents an empirical test of the model's critical prediction that manipulations that influence criterion placement should influence both remember and know judgments. An experiment confirmed this prediction, demonstrating that subjects who were told that 70% of the test items were study items produced more remember and know responses than subjects who were told that 30% of the test items were study items.

Administration of dehydroepiandrosterone (DHEA) enhances visual-spatial performance in postmenopausal women

The current article examines the effect of administering dehydroepiandrosterone (DHEA) on visual-spatial performance in postmenopausal women (N = 24, ages 55-80). The concurrent reduction of serum DHEA levels and visual-spatial performance in this population, coupled with the documented effects of DHEA's androgenic metabolites on visual-spatial performance, suggests that DHEA administration may enhance visual-spatial performance. The current experiment used a double-blind, placebo-controlled crossover design in which 50 mg of oral DHEA was administered daily in the drug condition to explore this hypothesis. Performance on the Mental Rotation, Subject-Ordered Pointing, Fragmented Picture Identification, Perceptual Identification, Same-Different Judgment, and Visual Search tasks and serum levels of DHEA, DHEAS, testosterone, estrone, and cortisol were measured in the DHEA and placebo conditions. In contrast to prior experiments using the current methodology that did not demonstrate effects of DHEA administration on episodic and short-term memory tasks, the current experiment demonstrated large beneficial effects of DHEA administration on Mental Rotation, Subject-Ordered Pointing, Fragmented Picture Identification, Perceptual Identification, and Same-Different Judgment. Moreover, DHEA administration enhanced serum levels of DHEA, DHEAS, testosterone, and estrone, and regression analyses demonstrated that levels of DHEA and its metabolites were positively related to cognitive performance on the visual-spatial tasks in the DHEA condition.

Evidence that episodic memory impairment during tobacco abstinence is independent of attentional mechanisms

Previous studies have demonstrated reductions in episodic memory during nicotine withdrawal. However, these studies have been unable to dissociate memory reductions from losses in attention associated with tobacco abstinence. In the present study, the authors sought to determine whether episodic memory reduction is a primary effect of nicotine withdrawal during tobacco abstinence. Heavy smokers were tested when smoking normally and following 24 hrs of abstinence. Participants were tested with a recognition memory task in which items were studied under full and divided attention conditions. Forward digit span and backward digit span were also included as control measures. Withdrawal was associated with a reduction in memory performance that was independent of attention at encoding. The authors conclude that impairment of episodic memory is a primary effect of nicotine withdrawal during tobacco abstinence. Further research is required to determine if this is associated with continued use of tobacco and cessation failures.

Oral contraceptives and androgenicity: influences on visuospatial task performance in younger individuals

The current study investigated whether the androgenic activity of oral contraceptives (OC) mediates performance on sexually dimorphic cognitive tasks in 155 younger individuals. Participants were categorized by hormonal contraceptive use (user vs. nonuser) and the androgenic activity of each OC (OC generation). OC generation was determined based on previous research in which users are grouped based on the type of progestin contained in each OC. Cognitive tasks included the mental rotation task (MRT) and a recognition memory task. In addition, we examined the correlates of both menstrual cycle phase and OC use, such as mood, premenstrual syndrome, depression, blood pressure, and body fat using standardized measures. The main result was that OC androgenicity influenced MRT performance. Second generation OCs are the most androgenic. Thus, MRT performance was best in these OC users as compared to third generation users, Yasmin users and nonusers. On the other hand, Yasmin, a newer generation of OC, contains an "antiandrogenic" progestin, dropirenone. Yasmin users not only performed more poorly on the MRT in comparison to second and third generation pill users, but they performed significantly worse than OC nonusers. Results show that the androgenic activity in OCs influences MRT performance in the presence of static estrogen levels. Overall, the resulting pattern is consistent with a broad range of results demonstrating that visuospatial performance may be enhanced in women who are exposed to androgenic treatments. Furthermore, visuospatial performance is hindered with the introduction of antiandrogenic preparations.

Lower blood pressure correlates with poorer performance on visuospatial attention tasks in younger individuals

The relationship between low blood pressure and cognitive function among younger individuals is not fully understood. While a number of studies have examined hypertensive and hypotensive individuals, particularly in older populations, little attention has been devoted to healthy, young populations. We tested 105 healthy young individuals whose blood pressure levels naturally fell in the below normal-to-normal range. Our primary finding was a positive relation between blood pressure and cognition, as measured by two visuospatial attention tasks. This relation appears to be specific to visuospatial skills, as no relationship was observed between recognition memory and blood pressure. We discuss possible explanations for this positive relationship, such as structural neural mechanisms, and how they apply to the overall blood pressure-cognition relationship.

Midazolam amnesia and short-term/working memory processes

We examined whether midazolam impairs short-term/working memory processes. We hypothesize that prior dissociations in midazolam's effects on short-term/working memory tasks and episodic memory tasks arise because midazolam has a larger effect on episodic memory processes than on short-term/working memory processes. To examine these issues, .03 mg/kg of participant's bodyweight of midazolam was administered in a double-blind placebo-controlled within-participant design. Performance on the digit span and category generation/recall tasks was examined. The results of Experiment 1 demonstrated that: (1) midazolam impaired performance on the digit span task; (2) midazolam did not impair performance on the category generation task; (3) midazolam impaired performance on the category recall task; and (4) midazolam's effect on category recall was four times as large as its effect on digit span. The results of Experiment 2 demonstrated that midazolam did not impair digit span performance when the digit span task was administered at a later time. These results suggest that midazolam can impair short-term/working memory processes, but these effects are substantially smaller than midazolam's effect on episodic memory processes. Moreover, they demonstrate that conscious awareness of materials during study is not sufficient to produce episodic memory.

Combined pharmacological and electrophysiological dissociation of familiarity and recollection

Dual-process theories of recognition memory hypothesize separate underlying familiarity and recollection processes, but the necessity of multiple processes is debated. Previous research has suggested that scalp-recorded event-related brain potentials (ERPs) may index the activity of separate familiarity and recollection processes. Other research indicates that the amnestic drug midazolam impairs recollection more than familiarity. Here, we used a convergent pharmacological and electrophysiological approach to manipulate and monitor human brain activity and provide evidence for separate processes. Midazolam selectively influenced the putative ERP-correlate of recollection but not the putative ERP-correlate of familiarity. Under control conditions (saline), subjects' accuracy correlated with the recollection-related but not the familiarity-related ERP component, suggesting that recollection was dominant in driving memory. The opposite pattern was observed under midazolam administration, suggesting that when recollection fails, subjects may leverage familiarity to compensate. Thus, in contrast to perspectives holding that familiarity represents the default process, these results suggest that recollection was dominant until its impairment unveiled the influence of familiarity.

Episodic representations support early semantic learning: evidence from midazolam induced amnesia

Current controversy exists regarding the role of episodic representations in the formation of long-term semantic memories. Using the drug midazolam to induce temporary amnesia we tested participants' memories for newly learned facts in a semantic cue condition or an episodic and semantic cue condition. Following midazolam administration, memory performance was superior in the episodic and semantic condition, suggesting early semantic learning is supported by episodic representations.

Metamemory without the memory: are people aware of midazolam-induced amnesia?

RATIONALE

Midazolam is a benzodiazepine which produces a dense anterograde amnesia, while permitting relatively well-preserved short-term memory, semantic retrieval, and other higher cognitive functions. Given these preserved abilities, we were interested in whether or not participants given midazolam would be aware of this anterograde amnesia.

METHOD

In the present experiment, participants were given midazolam in one testing session and a saline placebo in another. Participants provided judgments-of-learning (JOLs) immediately following study of cue-target pairs. During the test phase of the experiment, confidence levels and feeling-of-knowing (FOK) judgments were collected.

RESULTS

Although cued recall performance was substantially impaired in the midazolam condition, mean JOLs were unaffected, indicating participants had little insight into their impairment during the study phase. Participants were relatively accurate in confidence levels and FOK judgments in the midazolam condition.

CONCLUSION

When studying items under the influence of midazolam, participants are unaware that their memory will be impaired. Implications for clinical practice and pharmacological studies of amnesia are discussed.

The effect of midazolam on implicit and explicit memory in category exemplar production and category cued recall

Transfer-appropriate processing theory (Roediger, Weldon, & Challis, 1989) proposes that dissociations between performance on explicit and implicit memory tests arise because these tests often rely on different types of information processing (e.g., perceptual processing vs conceptual processing). This perspective predicts that implicit and explicit memory tasks that rely primarily on conceptual processing should show comparable results, not dissociations. Numerous studies have demonstrated such similarities. It is, however, possible that these results arise from explicit memory contamination of performance on implicit memory tasks. To address this issue, an experiment was conducted in which participants were administered the sedative midazolam prior to study. Midazolam is known to create a temporary, but dense, period of anterograde amnesia. The effects of blocking stimulus materials by semantic category at study and generation at study were investigated on category exemplar production and category-cued recall. The results of this study demonstrated a dissociation of the effects of midazolam on category exemplar production and category-cued recall. Specifically, midazolam reduced the effect of blocking stimulus materials in category-cued recall, but not in category exemplar production. The differential effect of midazolam on explicit and implicit memory is at odds with transfer-appropriate processing theory and suggests that theories of memory must distinguish the roles of different types of conceptual processing on implicit and explicit memory tests.

Evidence that androgenic and estrogenic metabolites contribute to the effects of dehydroepiandrosterone on cognition in postmenopausal women

Prior studies of the effects of dehydroepiandrosterone (DHEA) on cognition have produced complex and inconsistent results. We hypothesize that these results may arise, in part, because of DHEA's metabolism into estrogens and androgens that produce opposing effects on cognition. Our study administered 50 mg of oral DHEA daily for 4 weeks in a placebo-controlled crossover design to six postmenopausal women. We measured blood levels of androgens (total testosterone, free testosterone, DHEA, DHEAS), estrogens (estradiol, estrone), and cognitive performance on recognition memory, perceptual identification, digit span memory, and visual attentional vigilance under both drug and placebo conditions. Multiple regression models incorporating the factors of age and body mass index (BMI) were used to ascertain the relation between sex steroids and cognitive performance. Our results demonstrated that estrogens produced a positive effect on recognition memory, while androgens produced a negative effect. This pattern reversed in perceptual identification with estrogens producing a negative effect and androgens producing a positive effect. In addition, BMI produced a negative effect on digit span memory, age produced a negative effect on perceptual identification, and androgens produced a negative effect on visual attentional vigilance. These results help, in part, to explain DHEA's complex effects on cognition. The diverse effects of sex steroids across tasks underscore the importance of identifying the specific cognitive mechanisms influenced by sex steroids and emphasizes that one should not expect sex steroids to produce homogeneous effects across cognitive tasks.

The effect of tobacco abstinence on recognition memory, digit span recall, and attentional vigilance

This article examines the effects of tobacco abstinence on recognition memory, digit span recall, and visual attentional vigilance. The results demonstrated that abstinence impaired recognition memory discrimination (ad libitum d' =.85, abstinent d' =.64), recognition memory hit rates (ad libitum =.60, abstinent =.54), accuracy of target detection in attentional vigilance (ad libitum =.99, abstinent =.97), and speed of target detection in attentional vigilance (ad libitum = 662 ms, abstinent = 687 ms). Abstinence did not impair digit span recall (ad libitum =.55, abstinent =.56). These results are consistent with the hypotheses that tobacco abstinence impairs episodic memory and sustained attention. They also suggest that some, but not necessarily all, short-term memory processes may not be influenced by tobacco abstinence.

Ordinal Process Dissociation and the Measurement of Automatic and Controlled Processes

The process-dissociation equations (L. Jacoby, 1991) have been applied to results from inclusion and exclusion tasks to derive quantitative estimates of the influence of controlled and automatic processes on memory. This research has provoked controversies (e.g., T. Curran & D. Hintzman, 1995) regarding the validity of specific assumptions underlying the process-dissociation equations. In this article, the author explores the conclusions one can draw about the ordinal relations between automatic and controlled processes across experimental conditions from results in the inclusion and exclusion tasks. Given relatively neutral assumptions, this article presents and proves 6 theorems that allow investigators to draw conclusions about the ordinal relations between automatic and/or controlled processes across experimental conditions. An illustrative example is presented, and the current approach is compared with the original process-dissociation framework.

Midazolam amnesia and retrieval from semantic memory: Developing methods to test theories of implicit memory

Studies of organic anterograde amnesia have been central to the development of theories of implicit memory. Pharmacological amnesia provides an additional method for exploring implicit memory, allowing for the experimental manipulation of amnesia and the testing of more participants. A significant concern with pharmacological amnesia is whether its cognitive effects are specific to explicit memory. The current research examines the effects of the benzodiazepine, midazolam, on retrieval from semantic memory and encoding in explicit memory. We focus on midazolam because it holds significant advantages over other benzodiazepines in inducing pharmacological amnesia and prior research suggests it may be useful for testing theories of implicit memory. Our results demonstrate that midazolam does not impair accuracy of retrieval from semantic categories, even when it produces anterograde amnesia for retrieved category items on a later recall test. These results suggest ways midazolam can be used to help test theories of implicit memory.

The effect of midazolam on conscious, controlled processing: Evidence from the process-dissociation procedure

The benzodiazepine midazolam produces a dense anterograde amnesia. Recent findings (see, e.g., Hirshman, Passannante, & Arndt, 2001) have demonstrated that midazolam produces larger impairments on explicit memory tests such as free recall and recognition memory than on implicit memory tests such as perceptual identification and free association. Such findings suggest that midazolam impairs conscious, controlled memory processes. In the present experiments, we used Jacoby's (1991, 1998) process-dissociation procedure to examine this hypothesis. Our results demonstrate that midazolam increases the production of old items on the exclusion task and reduces the production of old items on the inclusion task. Moreover, generation effects, hypothesized to arise from conscious processes, are reduced by midazolam on both tasks. Analyses using both independence and redundancy models of the process-dissociation procedure confirm the conclusion that midazolam impairs conscious memory processes.

A paradoxical dissociation in the effects of midazolam on recollection and automatic processes in the process dissociation procedure

This study used midazolam-induced amnesia to explore the plausibility of the estimates provided by the process dissociation procedure (PDP), which is designed to estimate the contributions of recollection (R) and automatic (A) processes to implicit memory performance. In a double-blind, placebo-controlled, within-subject design with 24 participants, single midazolam doses were administered intravenously, and word stem completion performance was used to calculate PDP estimates. A dissociation was observed such that midazolam decreased R but increased A estimates relative to placebo. Given that a manipulation that induces amnesia would not be expected to facilitate a memory process, these results add to the accumulating body of evidence suggesting that PDP estimates are not always theoretically plausible. Such evidence raises important questions about the use of the PDP.

The effect of dehydroepiandrosterone (DHEA) on recognition memory decision processes and discrimination in postmenopausal women

In this article, the theoretical distinction between recognition memory decision and discrimination processes is used to explore the effect of dehydroepiandrosterone (DHEA) in postmenopausal women. DHEA is an adrenal steroid that diminishes with aging. It has enhanced memory in laboratory animals. An 8-week placebo-controlled, double-blind experiment in which 30 women (ages 39-70) received a 50-mg/day oral dose of DHEA for 4 weeks demonstrated that DHEA made subjects more conservative (i.e., less likely to call test items "old") in their recognition memory decisions and enhanced recognition memory discrimination for items presented briefly. The former result may reflect an empirical regularity (Hirshman, 1995) in which recent strong memory experiences make participants more conservative. The latter result may reflect the effect of DHEA on visual perception, with consequent effects on memory. These results suggest the methodological importance of focusing on decision processes when examining the effects of hormones on memory.

Midazolam amnesia and conceptual processing in implicit memory

Prominent theories of implicit memory (D. Schacter, B. Church, & J. Treadwell, 1994) emphasize the dominant role of perceptual processing in mediating priming on perceptual implicit memory tests. Examinations of the effects of conceptual processing on perceptual implicit memory tests have produced ambiguous results. Although a number of investigations (e.g., J. Toth & R. Hunt, 1990) have demonstrated that variations in conceptual processing affect priming on perceptual implicit memory tests, these effects may arise because of the contaminating effects of explicit memory. The current experiment examined this controversy using midazolam, a benzodiazepine that produces a dense, albeit temporary, anterograde amnesia when injected prior to study. The experiment examined whether the effects of generation found on the implicit memory test of perceptual identification were affected by a midazolam injection prior to study. Results demonstrated that midazolam substantially diminished generation effects in free and cued recall, as well as overall performance on these tests, but had no detectable effect on the generation effect in perceptual identification.

False memories and statistical decision theory: comment on Miller and Wolford (1999) and Roediger and McDermott (1999)

In an analysis of H. L. Roediger and K. B. McDermott's (1995) false-memory paradigm, M. B. Miller and G. L. Wolford (1999) argued that falsely recognized items occur because a bias toward calling such items "old" is created by their membership in a studied category. This interpretation was contested by Roediger and McDermott (1999). The authors of this article approach this issue as a statistical decision problem and observe that an explanation of false memory based on stored strengths and one based on decision process can have identical implications for data. Problems with equivalent formal models of this type can frequently be resolved by looking at the effects of other variables on the fitted estimates. The authors illustrate this analysis by examining the effects of presentation duration on the parameter estimates produced by models that instantiate the 2 explanations. Although the question remains open, the storage-based interpretation was found to be somewhat more plausible.

Using ROC curves to test models of recognition memory: the relationship between presentation duration and slope

Many theories of memory predict that the slope of the z-transformed receiver-operating characteristic (ROC) curve should decrease with increases in the memory strength of old items. While several prior studies have failed to demonstrate this effect, the results of two experiments demonstrate that increasing presentation duration can reduce the slope of the z-transformed ROC curve. These results raise questions about the generality of prior results and of dual-process theories designed to accommodate those results. We close by emphasizing that determining the experimental circumstances that affect whether or not the slope of the z-transformed ROC curve decreases will provide important constraints on theories of recognition memory.

The effect of midazolam on implicit memory tests

Substantial empirical evidence exists suggesting that there are distinct forms of explicit and implicit memory. However, methodological problems have hampered attempts to identify the nature of the information processing underlying these forms of memory. These problems include the contamination of performance on implicit memory tests by explicit memory processes, as well as a host of difficulties inherent in correlational approaches that involve amnesiac subjects. In this paper we attempt to explore whether midazolam, a benzodiazepine used in surgical anesthesia, might be useful for studying implicit memory. Specifically, we attempt to determine whether midazolam produces selective effects on explicit, as opposed to implicit, memory. We focus on midazolam because of prior studies demonstrating that benzodiazepines do not affect implicit memory and because its rapid pharmacokinetics ensure that sedative effects are minimized when testing occurs at relatively short retention intervals. The results of an experiment using free recall, fragment completion and perceptual identification tests suggest that midazolam diminishes memory in implicit and explicit memory tests, although the diminution is proportionally larger in explicit memory. These results constrain the inferences that may be drawn when midazolam is used to explore implicit memory.

The effect of midazolam on the modality-match effect in implicit memory

Prominent theories of implicit memory claim that perceptual processes play a central role in implicit memory. The modality-match effect, the finding that priming is greater when the modality of stimulus presentation matches at study and test, provides the central evidence for these approaches. In this paper we use the benzodiazepine, midazolam, to explore the nature of the modality-match effect in implicit memory. We compared the modality-match effect in a midazolam and a saline (i.e., a placebo) condition. Our experimental results demonstrate that the modality-match effect is diminished substantially in a midazolam condition even though components of priming are preserved. Given the empirically-validated assumption that midazolam minimizes explicit memory, these results suggest that there exist components of implicit memory that are not mediated by perceptual processes and raise questions about the generality of prominent theories of implicit memory.

On the logic of testing the independence assumption in the process-dissociation procedure

The process-dissociation procedure is designed to provide quantitative estimates of the influence of explicit and implicit memory in a variety of tasks. The procedure relies on the assumption that these two forms of memory produce independent influences on performance. Prior investigators have attempted to test this assumption by determining whether the parameter representing the influence of implicit memory (denoted A) is constant across experimental conditions. I argue that the constancy of A cannot provide an appropriate test of the independence assumption, because (1) the prediction of constancy can be generated without the assumption of independence, obviating the need to posit independence; and (2) the constancy of A does not necessarily imply independence, even if one assumes that a dependency hypothesis, supplemented by ancillary assumptions (Curran & Hintzman, 1995), predicts differences in A. I close by emphasizing that we can test the independence assumption by using standard procedures that compare the fit of a model that assumes independence with the fit of a model that assumes dependence.

Dual-mode presentation and its effect on implicit and explicit memory

We empirically investigated whether the auditory and visual subsystems mediating priming interact. We examined the hypothesis that processing in the visual subsystem during an implicit memory test permits access to memories in the auditory subsystem that were stored concurrently with visual memories. We did so by comparing priming in visual perceptual identification following both visual and auditory presentation (multimodal priming), only visual presentation (within-modality priming), or only auditory presentation (cross-modality priming). We focused on the comparison between multimodal and within-modality priming because multimodal priming should be larger than within-modality priming under our hypothesis. However, multimodal priming was approximately equal to within-modality priming in four experimental conditions. These results are consistent with the view that there is limited interaction between the visual and auditory subsystems mediating priming.

Predicting the future and reconstructing the past: a Bayesian characterization of the utility of subjective fluency

The subjective sense of fluency with which an item can be perceived or remembered is proposed to be a vital cue in making decisions about the future memorability and the nature of our past experience with that stimulus. We first outline a number of cases in which such perceptual or retrieval fluency influences judgments both about our own future performance and our likely past experience, and then present a Bayesian analysis of how judgments of recognition--deciding whether or not a currently viewed item was studied at a particular point in the past--may incorporate information about the perceptual fluency of that item. Using a simple mathematical model, we then provide an interpretation of certain enigmatic phenomena in recognition memory.

Modeling the conscious correlates of recognition memory: reflections on the remember-know paradigm

Understanding how memory processes contribute to the conscious experience of memory is central to contemporary cognitive psychology. Recently, many investigators (e.g., Gardiner, 1988) have examined the remember-know paradigm to understand the conscious correlates of recognition memory. A variety of studies have demonstrated that variables have different effects on remember and know responses, and these findings have been interpreted in the context of dual-process models of recognition memory. This paper presents a single-process model of the remember-know paradigm, emphasizing the dependence of remember and know judgments on a set of common underlying processes (e.g., criterion setting). We use this model to demonstrate how a single-process model can give rise to the functional dissociations presented in the remember-know literature. We close by detailing procedures for testing our model and describing how those tests may facilitate the development of dual-process models.

The sensory match effect in recognition memory: perceptual fluency or episodic trace?

The sensory match effect in recognition memory refers to the finding that recognition is better when the sensory form in which an item is tested is the same as that in which it was studied. This paper examines the basis for the sensory match effect by manipulating whether a studied fragmented picture is tested with the same or a complementary set of fragments in a recognition memory test (Experiment 1) and in a fragment-identification test (Experiment 2). Assuming that fragment identification is a direct measure of perceptual fluency, we expected identical patterns of results across the two tests if perceptual fluency accounted for the sensory match effect in recognition memory. Instead, recognition memory showed a robust overall sensory match effect (the same fragmented image was recognized better than the complementary image), whereas fragment identification showed no overall sensory match effect (the same fragmented image was identified no better than the complementary fragmented image). Experiments 3 and 4 combined the two responses and showed that the basis for the sensory match effect in recognition memory was a subject's ability to recognize the matching fragments in the absence of conceptual information (when the test stimulus could not be identified), supporting the idea that the episodic trace of the sensory code is responsible for the sensory match effect in recognition memory. Experiment 5 demonstrated that subjects are able to use this sensory code as the sole basis for recognition memory.

Decision processes in recognition memory: criterion shifts and the list-strength paradigm

This article focuses on decision processes in recognition memory. It begins with investigation of the hypothesis that the measured criterion increases systematically with the memorability of old items. Three experiments using the list-strength paradigm, and a review of the prior literature, present results consistent with this hypothesis. Several psychological models of criterion placement are examined, generating different predictions about the relative sizes of criterion shifts for strong and weak items. A range model, in which criterion placement depends on the estimated range of the old and new distributions, predicts that criterion shifts should be larger for weak items; this result emerges in a reanalysis of prior studies. The general discussion elaborates on how a focus on criterion placement can explain the mirror effect (Glanzer, Adams, Iverson, & Kim, 1993) and provides a framework for testing Shiffrin, Ratcliff, and Clark's (1990) claims about why null effects of list strength occur with repetition.

Decision processes in recognition memory: criterion shifts and the list-strength paradigm

This article focuses on decision processes in recognition memory. It begins with investigation of the hypothesis that the measured criterion increases systematically with the memorability of old items. Three experiments using the list-strength paradigm, and a review of the prior literature, present results consistent with this hypothesis. Several psychological models of criterion placement are examined, generating different predictions about the relative sizes of criterion shifts for strong and weak items. A range model, in which criterion placement depends on the estimated range of the old and new distributions, predicts that criterion shifts should be larger for weak items; this result emerges in a reanalysis of prior studies. The general discussion elaborates on how a focus on criterion placement can explain the mirror effect (Glanzer, Adams, Iverson, & Kim, 1993) and provides a framework for testing Shiffrin, Ratcliff, and Clark's (1990) claims about why null effects of list strength occur with repetition.

Dissociations among implicit and explicit memory tasks: the role of stimulus similarity

This article compares the effect of picture fragmentation level at study on performance on a variety of implicit and explicit memory tests. Consistent with previous research, a moderately fragmented study picture produced the most learning on the implicit memory task of picture fragment completion (Experiment 1) and speeded picture identification (Experiment 4). In contrast, an intact study picture produced the most learning on the implicit memory task of naming intact pictures (Experiment 3). These results suggest that performance on 2 implicit memory tasks can be dissociated by differences in visual similarity between the study and test forms of a stimulus. More surprising, parallel effects were observed in recognition memory. Recognition memory was best when fragmentation levels of the study and test pictures matched (Experiment 2) or were comparable (Experiment 1). In contrast to many results in the literature, recognition memory was acutely sensitive to surface form differences. We discuss the results in terms of 2 types of study-test similarity-stimulus similarity and process similarity.

Dissociations among implicit and explicit memory tasks: the role of stimulus similarity

This article compares the effect of picture fragmentation level at study on performance on a variety of implicit and explicit memory tests. Consistent with previous research, a moderately fragmented study picture produced the most learning on the implicit memory task of picture fragment completion (Experiment 1) and speeded picture identification (Experiment 4). In contrast, an intact study picture produced the most learning on the implicit memory task of naming intact pictures (Experiment 3). These results suggest that performance on 2 implicit memory tasks can be dissociated by differences in visual similarity between the study and test forms of a stimulus. More surprising, parallel effects were observed in recognition memory. Recognition memory was best when fragmentation levels of the study and test pictures matched (Experiment 2) or were comparable (Experiment 1). In contrast to many results in the literature, recognition memory was acutely sensitive to surface form differences. We discuss the results in terms of 2 types of study-test similarity-stimulus similarity and process similarity.

Examining a processing tradeoff explanation of proactive interference

Burns (1989) claims that proactive interference effects occur in paired-associate learning because of tradeoffs in relational and response-specific processing. Consistent with this claim, Burns demonstrated that free recall of critical-list responses is better in the interference condition than in the control condition. Burns's processing tradeoff explanation predicts that the occurrence of this reverse-interference effect should be positively correlated with the occurrence of traditional interference effects. We present several experiments whose results are inconsistent with this prediction. We hypothesize that the reverse-interference effect is a list-length effect. The results of a final experiment, contrasting the predictions of the list-length and processing tradeoff explanations, support the list-length explanation.

Perceptual interference improves explicit memory but does not enhance data-driven processing

Nairne (1988) has recently demonstrated that interfering with the perceptual processing of an item at study improves later memory for that item. Nairne hypothesized that interfering with perceptual processes induces a data-driven generation process that enhances the representation of visual information. Using a variant of Nairne's procedure, we both replicated his original findings and tested his hypothesis that enhanced data-driven processing causes the current effect. The results of studies using free recall and perceptual identification tests were inconsistent with Nairne's hypothesis. We consider several alternative interpretations in the General Discussion.

Perceptual interference improves explicit memory but does not enhance data-driven processing

Nairne (1988) has recently demonstrated that interfering with the perceptual processing of an item at study improves later memory for that item. Nairne hypothesized that interfering with perceptual processes induces a data-driven generation process that enhances the representation of visual information. Using a variant of Nairne's procedure, we both replicated his original findings and tested his hypothesis that enhanced data-driven processing causes the current effect. The results of studies using free recall and perceptual identification tests were inconsistent with Nairne's hypothesis. We consider several alternative interpretations in the General Discussion.