Imagery encoding effects on memory in the DRM paradigm: A test of competing predictions

In three experiments the effects of imagery encoding and test format on false memory rates in the Deese–Roediger–McDermott (DRM) paradigm were examined. After generating images of individual items (Experiment 1) or integrated subsets (Experiment 2), all of which were embedded in thematically related lists, participants were surprised by a recognition memory test or one of three kinds of source tests. As predicted by a distinctive encoding hypothesis, generating individual images led to better accuracy on presented items, and better monitoring of critical lures, than generating integrated images (Experiments 1 and 2). However, both kinds of imagery encoding led to fewer endorsements of critical lures compared to a non‐imagery encoding condition (Experiment 3). Imagery encoding effects were also independent of test format. The implications of these findings for the use of DRM‐false memory rates in debates about the use of guided imagery techniques are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

True and false memory for colour names versus actual colours: Support for the visual distinctiveness heuristic in memory for colour information

In a colour variation of the Deese–Roediger–McDermott (DRM) false memory paradigm, participants studied lists of words critically related to a nonstudied colour name (e.g., “blood, cherry, scarlet, rouge … ”); they later showed false memory for the critical colour name (e.g., “red”). Two additional experiments suggest that participants generate colour imagery in response to such colour-related DRM lists. First, participants claim to experience colour imagery more often following colour-related than standard non-colour-related DRM lists; they also rate their colour imagery as more vivid following colour-related lists. Second, participants exhibit facilitative priming for critical colours in a dot selection task that follows words in the colour-related DRM list, suggesting that colour-related DRM lists prime participants for the actual critical colours themselves. Despite these findings, false memory for critical colour names does not extend to the actual colours themselves (font colours). Rather than leading to source confusion about which colours were self-generated and which were studied, presenting the study lists in varied font colours actually worked to reduce false memory overall. Results are interpreted within the framework of the visual distinctiveness hypothesis.     

Boundaries of the relation between conscious recollection and source memory for perceptual details

The relation between conscious recollection and source memory for perceptual details was investigated in three experiments that combined the remember-know paradigm with a multidimensional source monitoring test. Experiment 1 replicated that source memory for perceptual details is better in the case of "remember" than "know" judgments. Experiment 2 showed that the relation between "remember" judgments and source memory for perceptual details is diminished by a semantic orienting task during encoding. Experiment 3 demonstrated that "remember" judgments are related to enhanced source memory for specific and unique kinds of perceptual source information, whereas memory for incomplete and global perceptual source information does not differentiate between "remember" and "know" judgments. The results show that the attentional focus during encoding and the specificity of retrieved source information form boundary conditions for the use of source memory for perceptual details as a basis of "remember" judgments.     

错误记忆的自我参照效应：易化的作用

采用DRM范式,设置三种参照对象条件（自我、他人和中性参照）,考察错误记忆是否存在自我参照效应。结果发现：（1）与正确记忆一样,错误记忆中亦存在自我参照效应;（2）无论是正确记忆还是错误记忆,自我参照条件下的回忆成分均显著多于他人参照和中性参照,但熟悉性成分在三种不同参照对象条件下没有显著差异;（3）当词表中学习项目由分组呈现变为随机呈现时,错误记忆的自我参照效应仍稳定存在。结果揭示,自我参照效在促进正确记忆的同时,亦可易化错误记忆效应。     

表象编码对基于词表的错误记忆的影响

采用DRM范式,探讨不同表象编码时间和不同表象编码加工程度对基于词表的错误记忆的影响。在学习阶段,被试对呈现的词进行记忆。在测试阶段,被试在每个词列表学习结束后立即对该词列表进行自由回忆,分心任务结束后进行再认测试。实验结果发现：（1）被试在5秒编码条件下的错误记忆率显著低于3秒编码条件下的错误记忆率;（2）在5秒表象编码时间条件下,深加工组被试的错误记忆率显著低于浅加工组。这说明在较长的编码时间里,时间越长记住的细节信息越多,错误记忆率越低;加工程度越深,错误记忆率越低。     

表象编码对基于词表的错误记忆的影响

采用DRM范式,探讨不同表象编码时间和不同表象编码加工程度对基于词表的错误记忆的影响。在学习阶段,被试对呈现的词进行记忆。在测试阶段,被试在每个词列表学习结束后立即对该词列表进行自由回忆,分心任务结束后进行再认测试。实验结果发现：（1）被试在5秒编码条件下的错误记忆率显著低于3秒编码条件下的错误记忆率;（2）在5秒表象编码时间条件下,深加工组被试的错误记忆率显著低于浅加工组。这说明在较长的编码时间里,时间越长记住的细节信息越多,错误记忆率越低;加工程度越深,错误记忆率越低。     

Medial prefrontal cortex supports source memory for self-referenced materials in young and older adults

Behavioral evidence suggests that young and older adults show a benefit in source memory accuracy when processing materials in reference to the self. In the young, activity within the medial prefrontal cortex supports this source memory benefit at study. In this investigation, we examined whether the same neural regions support this memory benefit in both age groups. Using fMRI, we scanned participants while they studied and retrieved pictures of objects paired with one of three scenes (source) under self-reference and other-reference conditions. At the time of study, half of the items were presented once and half twice, allowing us to match behavioral performance between the groups. Both groups showed equivalent source accuracy benefits for objects encoded self-referentially. Activity in the left dorsal medial prefrontal cortex supported subsequent source memory in both age groups for the self-referenced relative to the other-referenced items. At the time of test, source accuracy for both the self- and other-referenced items was supported by a network of regions including the precuneus in both age groups. At both study and test, little in the way of age differences emerged, suggesting that when they are matched on behavioral performance, young and older adults engage similar regions in support of source memory when processing materials in reference to the self; however, when we did not match performance, age differences in functional recruitment were prevalent. These results suggest that by capitalizing on preserved processes (self-referential encoding), older adults can show improvement in memory for source details that they would typically not remember well, relative to the young.     

Backward associative strength determines source attributions given to false memories

Source attributions for falsely remembered material were investigated in two experiments. A male and a female speaker each presented either an entire word list or half of the items from each of multiple Deese-Roediger-McDermott (DRM) lists commonly used in this paradigm. In the latter condition the tendency of each list half to activate a nonpresented, critical list theme item was manipulated. All of the list halves differed in backward associative strength (BAS), and each was presented by one or the other of the two speakers. In these correlated conditions, when critical items were falsely recognized (Experiments 1 and 2) or recalled (Experiment 2), source attributions were more frequently made to the speaker of the list items with the higher average BAS. This source attribution effect appears to result from the binding of list item source characteristics to activated critical items during encoding, as opposed to being the result of a biased retrieval process. The results are interpreted as consistent with an activation/monitoring account of false memory in the DRM paradigm.     

Measuring the activation level of critical lures in the Deese-Roediger-McDermott paradigm

In four experiments, the activation level in memory of critical lures was assessed after encoding Deese-Roediger-McDermott (DRM) lists. The results demonstrated that studying longer, 14-item lists resulted in superadditive priming of the lures because they were more available in memory than truly studied items. Studying shorter DRM lists resulted in activation levels of the lures that was similar to studied items. Collectively, the results suggest that a first stage in creating false memories with the DRM paradigm is making the critical lures highly available in memory during list encoding. Moreover, the results suggest that false memories are likely to have occurred at the time a list is studied by a mechanism such as an implicit associative response, but a monitoring phase at retrieval is acknowledged that could be used to avoid them. Other theoretical accounts are also considered.     

Reducing bias in frequency judgment by improving source monitoring

A common finding in judgment and decision making is that people's frequency judgments often fail to map onto objective frequencies. The present research examined the possibility that one source of bias in frequency judgment is attributable to people's inability to screen out irrelevant memory traces. We used a two-list source-monitoring paradigm to investigate whether frequency judgments are influenced by "extra-experimental" experiences and whether enhancing source monitoring improves judgment accuracy. Across four experiments we found: (1) frequency judgments regarding one list were biased by the second, (2) manipulating encoding between lists improved source monitoring and resulted in more accurate judgments, (3) manipulating item context between lists improved source monitoring and resulted in more accurate judgments, but only when the context was item specific, and (4) manipulating simple-background context between lists was ineffective at improving source monitoring.     

Test-induced priming of false memories

Of interest was whether prior testing of related words primes false memories in the Deese/Roediger-McDermott (DRM) paradigm. After studying lists of related words, subjects made old-new judgments about zero, three, or six related items before being tested on critical nonpresented lures. When the recognition test was self-paced, prior testing of list items led to faster false recognition judgments, but did not increase the rate of false alarms to lures from studied lists. Critically, this pattern changed when decision making at test was speeded. When forced to respond quickly—presumably precluding the use of monitoring processes—clear test-induced priming effects were observed in the rate of false memories. The results are consistent with an activation-monitoring explanation of false memories and support that retrieving veridical memories can be a source of memory error.     

Reduced effects of pictorial distinctiveness on false memory following dynamic visual noise

High levels of false recognition for non-presented items typically occur following exposure to lists of associated words. These false recognition effects can be reduced by making the studied items more distinctive by the presentation of pictures during encoding. One explanation of this is that during recognition, participants expect or attempt to retrieve distinctive pictorial information in order to evaluate the study status of the test item. If this involves the retrieval and use of visual imagery, then interfering with imagery processing should reduce the effectiveness of pictorial information in false memory reduction. In the current experiment, visual-imagery processing was disrupted at retrieval by the use of dynamic visual noise (DVN). It was found that effects of DVN dissociated true from false memory. Memory for studied words was not influenced by the presence of an interfering noise field. However, false memory was increased and the effects of picture-induced distinctiveness was eliminated. DVN also increased false recollection and remember responses to unstudied items.     

Schematic knowledge changes what judgments of learning predict in a source memory task

Source monitoring can be influenced by information that is external to the study context, such as beliefs and general knowledge (Johnson, Hashtroudi, & Lindsay, 1993). We investigated the extent to which metamnemonic judgments predict memory for items and sources when schematic information about the sources is or is not provided at encoding. Participants made judgments of learning (JOLs) to statements presented by two speakers and were informed of the occupation of each speaker either before or after the encoding session. Replicating earlier work, prior knowledge decreased participants’ tendency to erroneously attribute statements to schematically consistent but episodically incorrect speakers. The origin of this effect can be understood by examining the relationship between JOLs and performance: JOLs were equally predictive of item and source memory in the absence of prior knowledge, but were exclusively predictive of source memory when participants knew of the relationship between speakers and statements during study. Background knowledge determines the information that people solicit in service of metamnemonic judgments, suggesting that these judgments reflect control processes during encoding that reduce schematic errors.     

Pictorial encoding effects and memory confusions in the Deese-Roediger-McDermott paradigm: evidence for the activation of spontaneous imagery

The purpose of the experiments reported in this paper was to examine the possible role of spontaneous imagery and list-specific cues on pictorial encoding effects induced by the Deese-Roediger-McDermott (DRM) task. After viewing pictures and words referring to thematically related materials, by way of a picture/word source-judgement task, participants were asked to remember the way in which these materials were presented. Participants reported "seeing" pictures of items that were presented as words, an effect predicted by the imaginal activation hypothesis in its suggestion that incidental images experienced during encoding will later be mistaken as memories for pictures. Whether participants made the same picture misattributions on related lures (or non-presented related items) depended on the way in which the lures' respective thematic lists were experienced during encoding (Experiments 1 and 2), pointing to the effects of list-specific cues in picture/word judgements. These findings have intriguing implications for interpretations of picture-encoding effects induced by the DRM task. The findings also speak to the use of DRM false-memory rates when marshalling evidence against the use of imagery in applied settings.     

The effects of divided attention at study and test on false recognition: A comparison of DRM and categorized lists

Three experiments investigated the effects of divided attention at encoding and retrieval on false recognition. In Experiment 1, participants studied word lists in either full or divided attention (random number generation) conditions and then took part in a recognition test with full attention. In Experiment 2, after studying word lists with full attention, participants carried out a recognition test with either full or divided attention. Experiment 3 manipulated attention at both study and test. We also compared Deese/Roediger-McDermott (DRM) and categorized lists, due to recent claims regarding the locus of false memories produced by such lists (Smith, Gerkens, Pierce, & Choi, 2002). With both list types, false "remember" responses were reduced by divided attention at encoding and increased by divided attention at retrieval. The findings suggest that the production of false memories occurs as a result of the generation of associates at encoding and failures of source monitoring retrieval. Crucially, this is true for both DRM and categorized lists.     

Pictorial encoding effects and memory confusions in the Deese–Roediger–McDermott paradigm: Evidence for the activation of spontaneous imagery

The purpose of the experiments reported in this paper was to examine the possible role of spontaneous imagery and list-specific cues on pictorial encoding effects induced by the Deese-Roediger-McDermott (DRM) task. After viewing pictures and words referring to thematically related materials, by way of a picture/word source-judgement task, participants were asked to remember the way in which these materials were presented. Participants reported “seeing” pictures of items that were presented as words, an effect predicted by the imaginal activation hypothesis in its suggestion that incidental images experienced during encoding will later be mistaken as memories for pictures. Whether participants made the same picture misattributions on related lures (or non-presented related items) depended on the way in which the lures’ respective thematic lists were experienced during encoding (Experiments 1 and 2), pointing to the effects of list-specific cues in picture/word judgements. These findings have intriguing implications for interpretations of picture-encoding effects induced by the DRM task. The findings also speak to the use of DRM false-memory rates when marshalling evidence against the use of imagery in applied settings.     

Modality effect in false recognition: evidence from Chinese characters

Using the Deese/Roediger‐McDermott (DRM) false memory method, Smith and Hunt ( 1998 ) first reported the modality effect on false memory and showed that false recall from DRM lists was lower following visual study than following auditory study, which led to numerous studies on the mechanism of modality effect on false memory and provided many competing explanations. In the present experiment, the authors tested the modality effect in false recognition by using a blocked presentation condition and a random presentation condition. The present experiment found a modality effect different from the results of the previous research; namely, false recognition was shown to be greater following visual study than following auditory study, especially in the blocked presentation condition rather than in the random presentation condition. The authors argued that this reversed modality effect may be due to different encoding and processing characteristics between Chinese characters and English words. Compared with English words, visual graphemes of critical lures in Chinese lists are likely to be activated and encoded in participants' minds, thus it is more difficult for participants to discriminate later inner graphemes from those items presented in visual modality. Hence visual presentation could lead to more false recognition than auditory presentation in Chinese lists. The results in the present experiment demonstrated that semantic activation occurring during the encoding and retrieve phases played an important role in modality effect in false recognition, and our findings might be explained by the activation‐monitoring account.     

Generation and mnemonic encoding induce a mirror effect in the DRM paradigm

Encoding tasks that increase memory accuracy are appealing from both practical and theoretical perspectives. Within the Deese/Roediger-McDermott (DRM) paradigm, we found that generating list words from anagrams (relative to reading) produced a mirror effect: enhanced recognition of studied words coupled with a reduction in false recognition. Signal detection analyses suggest that the increase in correct recognition was due to enhanced item-specific encoding of the list words, whereas the reduction in false recognition was due to enhanced strategic monitoring at test (i.e., a distinctiveness heuristic), rather than to reduced relational encoding at study. Further support for a distinctiveness heuristic account was obtained using both "theme judgment" instructions and within-group conditions. In our final experiment, we replicated this mirror effect using a purely mnemonic (self-referential) encoding task, showing that extra perceptual cues are not necessary to induce participants to adopt a successful memory-improvement strategy at test.