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.     

Imagery encoding and false recognition errors: Examining the role of imagery process and imagery content on source misattributions

Imagery encoding effects on source-monitoring errors were explored using the Deese-Roediger-McDermott paradigm in two experiments. While viewing thematically related lists embedded in mixed picture/word presentations, participants were asked to generate images of objects or words (Experiment 1) or to simply name the items (Experiment 2). An encoding task intended to induce spontaneous images served as a control for the explicit imagery instruction conditions (Experiment 1). On the picture/word source-monitoring tests, participants were much more likely to report "seeing" a picture of an item presented as a word than the converse particularly when images were induced spontaneously. However, this picture misattribution error was reversed after generating images of words (Experiment 1) and was eliminated after simply labelling the items (Experiment 2). Thus source misattributions were sensitive to the processes giving rise to imagery experiences (spontaneous vs deliberate), the kinds of images generated (object vs word images), and the ways in which materials were presented (as pictures vs words).     

When plausibility manipulations work: An examination of their role in the development of false beliefs and memories

In the current study we examined whether prevalence information and imagery encoding influence participants' general plausibility, personal plausibility, belief, and memory ratings for suggested childhood events. Results showed decreases in general and personal plausibility ratings for low prevalence events when encoding instructions were not elaborate; however, instructions to repeatedly imagine suggested events elicited personal plausibility increases for low-prevalence events, evidence that elaborate imagery negated the effect of our prevalence manipulation. We found no evidence of imagination inflation or false memory construction. We discuss critical differences in researchers' manipulations of plausibility and imagery that may influence results of false memory studies in the literature. In future research investigators should focus on the specific nature of encoding instructions when examining the development of false memories.     

来源检测对表象引发的错误记忆的影响

采用“学习-再认”模式,考察来源检测对表象引发的错误记忆的影响。结果发现,在再认任务中,正确再认观察项目与想象项目的反应时差异不显著,但在源检测中,正确再认观察项目显著快于正确再认想象项目; 再认时与源检测时的错误再认率差异不显著,但对想象项目的错误再认率显著高于对观察项目。这表明,表象会导致错误记忆发生,提高来源检测操纵并不能够削弱表象引发的错误记忆。根据研究结果提出“表象激活混淆假设”,认为人们虽然使用表象的信息表征方式,却无法获取与之联系的激活路径,容易混淆表象激活的来源。表象激活混淆是表象引发错误记忆的机制。     

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.     

Encoding strategy affects false recall and recognition: Evidence from categorical study material

The present research investigated memory vulnerability to distortions. Different encoding strategies were used when categorized lists were studied. The authors assumed that an imagery strategy would be responsible for decreasing false memories more than a word-whispering strategy, which is consistent with the model of semantic access and previous research in the Deese-Roediger-McDermott paradigm (the DRM paradigm; Deese, 1959; Roediger & McDermott, 1995). A normative study of category lists and 4 experiments were conducted to verify the memory vulnerability to different encoding strategies (imagery, word-whispering, control). Half of subjects recalled and half recognized previously studied words. The results revealed a marked reduction in false recognition and recall after imagery encoding, relative to after word-whispering encoding.     

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.     

Source misattributions and false recognition errors: Examining the role of perceptual resemblance and imagery generation processes

In three experiments, we examine the extent to which participants’ memory errors are affected by the perceptual features of an encoding series and imagery generation processes. Perceptual features were examined by manipulating the features associated with individual items as well as the relationships among items. An encoding instruction manipulation was included to examine the effects of explicit requests to generate images. In all three experiments, participants falsely claimed to have seen pictures of items presented as words, committing picture misattribution errors. These misattribution errors were exaggerated when the perceptual resemblance between pictures and images was relatively high (Experiment 1) and when explicit requests to generate images were omitted from encoding instructions (Experiments 1 and 2). When perceptual cues made the thematic relationships among items salient, the level and pattern of misattribution errors were also affected (Experiments 2 and 3). Results address alternative views about the nature of internal representations resulting in misattribution errors and refute the idea that these errors reflect only participants’ general impressions or beliefs about what was seen.     

Source memory errors associated with reports of posttraumatic flashbacks: a proof of concept study

Flashbacks are involuntary, emotion-laden images experienced by individuals with posttraumatic stress disorder (PTSD). The qualities of flashbacks could under certain circumstances lead to source memory errors. Participants with PTSD wrote a trauma narrative and reported the experience of flashbacks. They were later presented with stimuli from flashback and non-flashback parts of their narrative, mixed with foils from the narrative of another participant, and judged whether they belonged to their own narrative. They also reported whether stimuli elicited a flashback during this recognition test. Overall reporting a flashback at test was associated with significantly better recognition performance. Flashbacks were occasionally reported to foil stimuli, which were then likely to be wrongly attributed to the person's own narrative. This provides proof of concept of a cognitive mechanism that could potentially account for some cases of false trauma memories.     

Role of response imagery on stimulus recognition*

This experiment investigated the role of response imagery on recognition of stimulus terms following associative training. Ss learned to associate 12 high-imagery or low-imagery responses with trigram stimuli by the study-associative matching procedure. Half the pairs were consistently paired and half were re-paired anew on each trial. Following associative training, Ss were given a stimulus recognition and an associative matching task The results indicated that the probability of stimulus recognition, given correct associative matching, was greater when the responses were high-imagery rather than low-imagery. In contrast, no rehable response imagery effects were found for the probability of stimulus recognition, given incorrect associative matching. It was argued that the locus of the response imagery effect was primarily during retrieval rather than during encoding.     

Conjunction errors in recognition memory: modality-free errors for older adults but not for young adults

A dual-process theory of memory was applied to processes in normal aging, with a focus on recognition errors in the feature-conjunction paradigm (i.e., false recognition of blackbird after studying parent words blackmail and/or jailbird). Study repetition was manipulated so that some parent words occurred once and others occurred three times. Age-related differences on hit scores occurred for two experiments. The results for feature and conjunction conditions showed repetition effects but no age-related differences when participants were uninformed of the lures (Experiment 1). However, age-related differences emerged when the retrieval of modality source information created a way to evade conjunction errors (Experiment 2). In the second experiment, study repetition decreased errors for the young adults but increased errors for the older adults, and young adults were better able than older adults to avoid conjunction errors when the parent words had been repeated. For older adults, the conjunction errors were modality-free. The results provide additional evidence that older adults experience difficulty in recollecting aspects of a study experience, and the results from groups of young adults required to respond quickly on the tests provide converging evidence for this conclusion.     

The effect of presentation format and encoding strategy on associative memory distortion

IntroductionPrevious studies using semantically related words revealed more accurate memory when the items were encoded visually rather than auditorily and when mental images were created during encoding. However, how the level of memory distortion is affected by the creation of different mental imagery formats or by techniques that should suppress generation of mental images has rarely been investigated.ObjectiveThe aim of the present studies was to investigate the ways in which the encoding strategy affects the accuracy of memory reports for two presentation formats of semantically related words: verbal and pictorial.MethodIn experiment 1, the participants were asked to memorize either pictures or their verbal equivalents (words) from the same category, using one of two encoding strategies: uttering the words or counting backwards. In experiment 2, pictorially or auditory presented material was encoded together with the creation of either visual or auditory mental images of the items. The results of the experimental groups were compared to control groups that received no specific instruction.ResultsHigher levels of false recognition, together with lower rates of correct recognition, were observed for words, presented either visually or auditory, relative to pictures. Moreover, self-generation of additional code during the processing of information favored the reduction of false recognitions.ConclusionEncoding strategies that engaged dual coding reduced false recognition. The results are discussed within the distinctiveness heuristic phenomenon.