Jason D. Ozubko

Production benefits both recollection and familiarity

In three experiments, we investigated the roles of recollection and familiarity in the production effect—the finding that words read aloud are remembered better than words read silently. Experiment 1, using the remember/know procedure, and Experiment 2, using the receiver operating characteristic procedure, converged in demonstrating that production enhanced both recollection and familiarity. Experiment 3 supported the role of recollection by demonstrating that specific episodic information—that is, whether a word had been studied aloud or silently—was stronger for items studied aloud. These findings fit with an explanation of the production effect as hinging on two factors: greater recollection of distinctive information from the study episode, and more familiarity due to greater attention allocated to the material studied aloud.

Production benefits learning: The production effect endures and improves memory for text

The production effect is the superior retention of material read aloud relative to material read silently during an encoding episode. Thus far it has been explored using isolated words tested almost immediately. The goal of this study was to assess the efficacy of production as a study strategy, addressing: (a) whether the production benefit endures beyond a short session, (b) whether production can boost memory for more complex material, and (c) whether production transfers to educationally relevant tests. In Experiment 1 a 1-week retention interval was included, and a production effect was observed. In Experiment 2 a production effect was observed for both word pairs and sentence stimuli. In Experiment 3 educationally relevant essays were read and tested with a fill-in-the-blanks test: Memory was superior for questions that probed information that had been read aloud relative to information that had been read silently. We conclude that the production benefit is enduring and generalises to text and different test formats, indicating that production constitutes a worthwhile study strategy.

Directed forgetting of visual symbols: Evidence for nonverbal selective rehearsal

Is selective rehearsal possible for nonverbal information? Two experiments addressed this question using the item method directed forgetting paradigm, where the advantage of remember items over forget items is ascribed to selective rehearsal favoring the remember items. In both experiments, difficult-to-name abstract symbols were presented for study, followed by a recognition test. Directed forgetting effects were evident for these symbols, regardless of whether they were or were not spontaneously named. Critically, a directed forgetting effect was observed for unnamed symbols even when the symbols were studied under verbal suppression to prevent verbal rehearsal. This pattern indicates that a form of nonverbal rehearsal can be used strategically (i.e., selectively) to enhance memory, even when verbal rehearsal is not possible.

Remembered study mode: Support for the distinctiveness account of the production effect

The production effect is the finding that words spoken aloud at study are subsequently remembered better than are words read silently at study. According to the distinctiveness account, aloud words are remembered better because the act of speaking those words aloud is encoded and later recovery of this information can be used to infer that those words were studied. An alternative account (the strength-based account) is that memory strength is simply greater for words read aloud. To discriminate these two accounts, we investigated study mode judgements (i.e., “aloud”/”silent”/”new” ratings): The strength-based account predicts that “aloud” responses should positively correlate with memory strength, whereas the distinctiveness account predicts that accuracy of study mode judgements will be independent of memory strength. Across three experiments, where the strength of some silent words was increased by repetition, study mode was discriminable regardless of strength—even when the strength of aloud and repeated silent items was equivalent. Consistent with the distinctiveness account, we conclude that memory for “aloudness” is independent of memory strength and a likely candidate to explain the production effect.

Forgetting Patterns Differentiate Between Two Forms of Memory Representation

For decades, there has been controversy about whether forgetting is caused by decay over time or by interference from irrelevant information. We suggest that forgetting occurs because of decay or interference, depending on the memory representation. Recollection-based memories, supported by the hippocampus, are represented in orthogonal patterns and are therefore relatively resistant to interference from one another. Decay should be a major source of their forgetting. By contrast, familiarity-based memories, supported by extrahippocampal structures, are not represented in orthogonal patterns and are therefore sensitive to interference. In a study in which we manipulated the postencoding task-interference level and the length of the delay between study and testing, we provide direct evidence in support of our representation theory of forgetting. Recollection and familiarity were measured using the remember/know procedure. We show that the causes of forgetting depend on the nature of the underlying memory representation, which places the century-old puzzle of forgetting in a coherent framework.

Remembering Makes Evidence Compelling: Retrieval from Memory Can Give Rise to the Illusion of Truth.

The illusion of truth is traditionally described as the increase in perceived validity of statements when they are repeated (Hasher, Goldstein, & Toppino, 1977). However, subsequent work has demonstrated that the effect can arise due to the increased familiarity or fluency afforded by repetition and not necessarily to repetition per se. We examine the case of information retrieved from memory. Recently experienced information is expected to be subsequently reexperienced as more fluent and familiar than novel information (Jacoby, 1983; Jacoby & Dallas, 1981). Therefore, the possibility exists that information retrieved from memory, because it is subjectively re-experienced at retrieval, would be more fluent or familiar than when it was first learned and would thus lead to an increase in perceived validity. Using a method to indirectly poll the perceived truth of factual statements, our experiment demonstrated that information retrieved from memory does indeed give rise to an illusion of truth. The effect was larger than when statements were explicitly repeated twice and was of comparable size to when statements were repeated 4 times. We conclude that memory retrieval is a powerful method for increasing the perceived validity of statements (and subsequent illusion of truth) and that the illusion of truth is a robust effect that can be observed even without directly polling the factual statements in question.

The mixed truth about frequency effects on free recall: Effects of study list composition

The mixed-list paradox is the finding that high-frequency words show a recall advantage in blocked lists, but that this advantage is reversed or nullified in mixed lists. We argue that this paradox has been poorly defined. Specifically, researchers should investigate random and alternating lists separately. We examine blocked, random, and alternating lists in our experiment. We hypothesize that a low-frequency recall advantage could arise due to asymmetrically strong links between low- and high-frequency words. Supporting our hypothesis, a lowfrequency recall advantage is observed in the random list, as is an asymmetry of association. In the alternating list, no recall advantage is observed, and neither is any asymmetry of association. Our results offer a clear challenge to future research to (1) consider the associations between word frequencies and (2) consider random and alternating lists separately.

The similarities (and familiarities) of pseudowords and extremely high-frequency words: Examining a familiarity-based explanation of the pseudoword effect.

The pseudoword effect is the finding that pseudowords (i.e., rare words or pronounceable nonwords) give rise to more hits and false alarms than words. Using the retrieving effectively from memory (REM) model of recognition memory, we tested a familiarity-based account of the pseudoword effect: Specifically, the pseudoword effect arises because pseudowords lack distinctive semantic meanings. Because semantics can differentiate orthographically similar words (e.g., horse vs. house), by lacking distinctive semantics, pseudowords have greater interitem similarity than words, and hence more familiarity, which gives rise to the pseudoword effect. Across two sets of simulations, we demonstrate that this account explains the pseudoword effect in addition to accounting for why the pseudoword effect is absent when irregular nonwords are compared with words. Furthermore, our modeling efforts suggest a novel experiment that leads us to the discovery of a new concordant effect. Namely, extremely high-frequency words behave like pseudowords (giving rise to more hits and false alarms than high-frequency words) and also have less distinctive semantics than high-frequency words. We conclude that our work provides strong evidence in favor of the familiarity-based accounts of the pseudoword effect. We discuss the implications of our research with regard to various issues surrounding the pseudoword effect and REM model.

The disruptive effects of processing fluency on familiarity-based recognition in amnesia.

Amnesia leads to a deficit in recollection that leaves familiarity-based recognition relatively spared. Familiarity is thought to be based on the fluent processing of studied items compared to novel items. However, whether amnesic patients respond normally to direct manipulations of processing fluency is not yet known. In the current study, we manipulated processing fluency by preceding each test item with a semantically related or unrelated prime item, and measured both recollection and familiarity using a remember-know recognition procedure. In healthy controls, enhancing processing fluency increased familiarity-based recognition responses for both old and new words, leaving familiarity-based accuracy constant. However, in patients with MTL damage, enhancing fluency only increased familiarity-based recognition responses for new items, resulting in decreased familiarity-based recognition accuracy. Importantly, this fluency-related decrease in recognition accuracy was not due to overall lower levels of performance or impaired recollection of studied items because it was not observed in healthy subjects that studied words under conditions that lowered performance by reducing recollection. The results indicate that direct manipulations of processing fluency can disrupt familiarity-based discrimination in amnesia. Potential accounts of these findings are discussed.

Super Memory Bros.: Going from mirror patterns to concordant patterns via similarity enhancements

When memory is contrasted for stimuli belonging to distinct stimulus classes, one of two patterns is observed: a mirror pattern, in which one stimulus gives rise to higher hits but lower false alarms (e.g., the frequency-based mirror effect) or a concordant pattern, in which one stimulus class gives rise both to higher hits and to higher false alarms (e.g., the pseudoword effect). On the basis of the dual-process account proposed by Joordens and Hockley (2000), we predict that mirror patterns occur when one stimulus class is more familiar and less distinctive than another, whereas concordant patterns occur when one stimulus class is more familiar than another. We tested these assumptions within a video game paradigm using novel stimuli that allow manipulations in terms of distinctiveness and familiarity (via similarity). When more distinctive, less familiar items are contrasted with less distinctive, more familiar items, a mirror pattern is observed. Systematically enhancing the familiarity of stimuli transforms the mirror pattern to a concordant pattern as predicted. Although our stimuli differ considerably from those used in examinations of the frequency-based mirror effect and the pseudoword effect, the implications of our findings with respect to those phenomena are also discussed.