Aging and the misinformation effect: a neuropsychological analysis

Older adults' susceptibility to misinformation in an eyewitness memory paradigm was examined in two experiments. Experiment 1 showed that older adults are more susceptible to interfering misinformation than are younger adults on two different tests (old-new recognition and source monitoring). Experiment 2 examined the extent to which processes associated with frontal lobe functioning underlie older adults' source-monitoring difficulties. Older adults with lower frontal-lobe-functioning scores on neuropsychological tests were particularly susceptible to false memories in the misinformation paradigm. The authors' results agree with data from other false memory paradigms that show greater false recollections in older adults, especially in those who scored poorly on frontal tests. The results support a source-monitoring account of aging and illusory recollection.     

Recollection can be weak and familiarity can be strong

The remember-know procedure is widely used to investigate recollection and familiarity in recognition memory, but almost all of the results obtained with that procedure can be readily accommodated by a unidimensional model based on signal-detection theory. The unidimensional model holds that remember judgments reflect strong memories (associated with high confidence, high accuracy, and fast reaction times), whereas know judgments reflect weaker memories (associated with lower confidence, lower accuracy, and slower reaction times). Although this is invariably true on average, a new 2-dimensional account (the continuous dual-process model) suggests that remember judgments made with low confidence should be associated with lower old-new accuracy but higher source accuracy than know judgments made with high confidence. We tested this prediction--and found evidence to support it--using a modified remember-know procedure in which participants were first asked to indicate a degree of recollection-based or familiarity-based confidence for each word presented on a recognition test and were then asked to recollect the color (red or blue) and screen location (top or bottom) associated with the word at study. For familiarity-based decisions, old-new accuracy increased with old-new confidence, but source accuracy did not (suggesting that stronger old-new memory was supported by higher degrees of familiarity). For recollection-based decisions, both old-new accuracy and source accuracy increased with old-new confidence (suggesting that stronger old-new memory was supported by higher degrees of recollection). These findings suggest that recollection and familiarity are continuous processes and that participants can indicate which process mainly contributed to their recognition decisions.     

The effects of initial testing on false recall and false recognition in the social contagion of memory paradigm

In three experiments, participants studied photographs of common household scenes. Following study, participants completed a category-cued recall test without feedback (Exps. 1 and 3), a category-cued recall test with feedback (Exp. 2), or a filler task (no-test condition). Participants then viewed recall tests from fictitious previous participants that contained erroneous items presented either one or four times, and then completed final recall and source recognition tests. The participants in all conditions reported incorrect items during final testing (a social contagion effect), and across experiments, initial testing had no impact on false recall of erroneous items. However, on the final source-monitoring recognition test, initial testing had a protective effect against false source recognition: Participants who were initially tested with and without feedback on category-cued initial tests attributed fewer incorrect items to the original event on the final source-monitoring recognition test than did participants who were not initially tested. These data demonstrate that initial testing may protect individuals’ memories from erroneous suggestions.     

Individual differences in working memory capacity affect false memories for missing aspects of events

Recently, Gerrie, Belcher, and Garry (2006) found that, when participants watch an event with parts missing, they falsely claim to have seen the missing parts--but they were more likely to claim they had seen less crucial parts than more crucial parts. Their results fit with a source-monitoring framework (SMF; Johnson, Hashtroudi, & Lindsay, 1993) explanation of false memories. In this paper we used individual differences in working memory capacity (WMC) to examine the SMF explanation of false memories for missing aspects of events. An accumulating body of research suggests that WMC is strongly related to controlling attention, including the ability to distinguish between sources of information. The primary purpose of the present study was to examine whether people with larger WMC are better able to ward off false memories for missing information than those with a smaller WMC. We showed that higher WMC reduced false recognition of crucial information, but did not change false recognition of noncrucial information. Additionally, we found that WMC had little effect on participants' subjective experience of true and false recognition of events, regardless whether the information was crucial or not. These results provide further evidence that people's WMC is related to their source-monitoring ability.     

Individual differences in working memory capacity affect false memories for missing aspects of events

Recently, Gerrie, Belcher, and Garry (2006) found that, when participants watch an event with parts missing, they falsely claim to have seen the missing parts—but they were more likely to claim they had seen less crucial parts than more crucial parts. Their results fit with a source-monitoring framework (SMF; Johnson, Hashtroudi, & Lindsay, 1993) explanation of false memories. In this paper we used individual differences in working memory capacity (WMC) to examine the SMF explanation of false memories for missing aspects of events. An accumulating body of research suggests that WMC is strongly related to controlling attention, including the ability to distinguish between sources of information. The primary purpose of the present study was to examine whether people with larger WMC are better able to ward off false memories for missing information than those with a smaller WMC. We showed that higher WMC reduced false recognition of crucial information, but did not change false recognition of noncrucial information. Additionally, we found that WMC had little effect on participants’ subjective experience of true and false recognition of events, regardless whether the information was crucial or not. These results provide further evidence that people's WMC is related to their source-monitoring ability.     

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.     

The influence of decision criteria upon remembering and knowing in recognition memory.

One may recognise an item as 'old' on basis of a recollective experience or by a feeling of familiarity without specific recollection. The former is called a 'remember' judgement; the latter a 'know' judgement. It has been claimed that remember and know responses reflect qualitatively distinct components of recognition memory, and not just derive from gradual differences in perceived trace strength or subjective certainty (i.e. remember judgments include memories of which one is more confident). Nonetheless, the present study examined the possibility that the distinction does relate to decision criteria placed upon a single familiarity axis (see Donaldson, 1996; Hirshman & Master, 1997). To this purpose, two groups of subjects were compared: one, which was instructed to be very conservative in their old-new judgements, while the other group was stimulated to be very lenient instead. Remember hit rates increased with more lenient criteria, whereas know hit rates did not, but false alarm rates did. While remember sensitivity was equal in the two groups, know sensitivity was lower with liberal criteria. Also it correlated with overall response bias. This lends support to the possibility that subjects not only apply an old-new decision criterion, but also set a remember-know criterion, which is affected in a similar way by liberal versus conservative instructions.     

When the half-full glass is appraised as half empty and memorised as completely empty: mood-congruent true and false recognition in depression is modulated by salience

Since the 1980s a large body of empirical effort has been devoted to mood-congruent memory (MCM) biases in clinical depression. Whereas there is broad, albeit not unequivocal, evidence that depressive patients retain negative-valenced memory items better than neutral material, few studies have investigated false memories in depression. In a pilot study we gathered support for both enhanced true and false memory for emotional material in depression. The present study aimed to extend these preliminary findings. In view of investigations suggesting that arousing and meaningful stimuli have facilitated access to memory, personal salience was considered a moderator for MCM. In the present study 21 depressed and 22 healthy participants were presented six false memory lists dealing with neutral, negative, and positive themes. At recognition, each item had to be appraised for its degree of valence subsequent to an old-new judgement. Pre-categorised and subjective valence did not discriminate groups. However, relative to controls depressed patients showed both more veridical as well as false recognition for items that concurrently elicited higher salience ratings in patients. In contrast, group differences in recognition performance did not significantly affect salience ratings. Results indicate that salience modulates MCM and may account for discrepancies in the literature.     

Explorations in the social contagion of memory

Four experiments examined social influence on the development of false memories. We employed the social contagion paradigm: A subject and a confederate see scenes and then later take turns recalling items from the scenes, with the confederate erroneously reporting some items that were not present in the scenes; on a final test, the subject reports these suggested items when instructed to recall only items from the scenes. The first two experiments showed that the social contagion effect persisted when subjects were explicitly warned about the possibility that confederates' responses might induce false memories and when they were tested via source-monitoring tests that explicitly gave the choice of attributing suggested items to the other person. Levels of false recall and recognition increased with the number of times the misleading information was suggested (Experiment 3), and subjects were more likely to incorporate the erroneous responses of an actual confederate on a recognition/source test as compared with those of a simulated confederate (Experiment 4). Collectively, the data support the claim that false memories may be transmitted between people and reveal critical factors that modulate the social contagion of memories.     

Inducing and reducing false memories: a Swedish version of the Deese-Roediger-McDermott paradigm

Participants tend to falsely remember a nonpresented critical word after having studied a list of the word's primary associates. We present here a Swedish version of the Deese-Roediger-McDermott paradigm, which provides a tractable method of experimentally inducing and investigating such illusory memories. In Experiment 1 it was demonstrated that the constructed stimulus material induced highly reliable false-recall and false-recognition effects, and, moreover, that veridical and false memories were associated with a similar phenomenological experience of remembering. The results from Experiment 2 indicated that the susceptibility to false recognition can be substantially reduced when participants are explicitly required to monitor the sources of their memories. These findings are consistent with predictions derived from the source-monitoring framework.     

Using recall to reduce false recognition: diagnostic and disqualifying monitoring

Whether recall of studied words (e.g., parsley, rosemary, thyme) could reduce false recognition of related lures (e.g., basil) was investigated. Subjects studied words from several categories for a final recognition memory test. Half of the subjects were given standard test instructions, and half were instructed to use recall to reduce false recognition. Manipulation checks indicated that the latter instructions did elicit a recall-to-reject strategy. However, false recognition was selectively reduced only when all the words from a category could be recalled (Experiment 1). When longer categories were used, thereby minimizing exhaustive recall, a recall-to-reject strategy was ineffective at reducing false recognition (Experiment 2). It is suggested that exhaustively recalling a category allowed subjects to disqualify the lure as having occurred, analogous to recall-to-reject demonstrations in other tasks. In contrast, partially recalling a category did not help to diagnose the lure as nonstudied. These findings constrain theories of recall-based monitoring processes.     

The nature of memory processes underlying recognition judgments in the process dissociation procedure

The hypothesis is tested that the memory processes involved in recognition judgments in the process dissociation procedure are the same as those involved in standard source-monitoring tasks. It is shown how source-monitoring response categories can be mapped onto process dissociation response categories. On the basis of this observation, an experiment was conducted in which it was possible to compare, using a multinomial modeling approach, the parameters representing memory processes in the process dissociation procedure with those involved in source monitoring. For the two different encoding conditions realized, the results are compatible with the hypothesis that the same processes are involved in source monitoring and in recognition judgments in the process dissociation procedure. Implications for the interpretation of the model’s parameters are discussed.     

Associative false recognition occurs without strategic criterion shifts

In the DRM (Deese/Roediger and McDermott) false memory paradigm, subjects studied lists of words associated with nonpresented critical words. They were tested in one of four instructional conditions. In a standard condition, subjects were not warned about the DRM Effect. In three other conditions, they were told to avoid false recognition of critical words. One group was warned before study of the lists (affecting encoding and retrieval processes), and two groups were warned after study (affecting only retrieval processes). Replicating prior work, the warning before study considerably reduced false recognition. The warning after study also reduced false recognition, but only when critical items had never been studied; when critical items were studied in half the lists so that subjects had to monitor memory for their presence or absence, the warning after study had little effect on false recognition. Because warned subjects were trying to avoid false recognition, the high levels of false recognition in the latter condition cannot be due to strategically guessing that critical test items were studied. False memories in the DRM paradigm are not caused by such liberal criterion shifts.     

Effects of free and forced retrieval instructions on false recall and recognition.

One hundred undergraduates heard 6 lists of 14 words that were each associated with 1 of 6 central concepts not on the lists (the DRMRS procedure). The participants were instructed to recall as many words as possible (free retrieval) or to fill all 14 spaces (forced retrieval) and were subsequently given a recognition test. False recall and recognition of the critical central concepts were higher with forced than with free retrieval instructions, but correct recall and recognition were not affected. Confidence was lower for false than for correct recall and recognition. Confidence was also lower with forced than with free retrieval instructions for false recall but not for false recognition. The DRMRS procedure easily elicited false memories, but confidence judgments helped more in detecting them in recall than in recognition. Theoretical and applied implications are discussed.     

Source misattributions may increase the accuracy of source judgments

Misattribution of remembered information from one source to another is commonly associated with false memories, but we demonstrate that it also may underlie memories that accord with past events. Participants imagined drawings of objects in four different locations. For each, a drawing of a similarly shaped object was seen in the same location, a different location, or not seen. When tested on memory for objects' origin (seen/imagined) and location, more false "seen" responses, but also more correct location responses, were given to imagined objects if a similar object had been seen, versus not seen, in the same location. We argue that misattribution of feature information (e.g., shape, location) from seen objects to similar imagined ones increased false memories of seeing objects but also increased correct location memories, provided the misattributed location matched the imagined objects' location. Thus, consistent with the source-monitoring framework, imperfect source-attribution processes underlie false and true memories.     

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.     

The effect of study modality on false recognition

A number of previous studies have shown that false recognition of critical items in the Deese/Roediger-McDermott paradigm is reduced when study items are presented visually rather than auditorily; however, this effect has not been uniformly demonstrated. We investigated three potential boundary conditions of the effect of study modality in false recognition. Experiments 1 and 2 showed no reduction in false recognition following visual study presentation when the yes-no recognition test was not preceded by a recall test. Experiment 3 showed that visual study presentation can reduce false recognition without a preceding recall test, if the recognition test uses remember-know instructions. The order of the recognition test items did not influence the effect of visual study presentation on false recognition in Experiment 1. In general, the data imply that distinctive processing at study can reduce false memory in recognition if the test demands draw attention to the dimension of distinctive processing.     

False recognition in women with a history of childhood emotional neglect and diagnose of recurrent major depression

While previous research has suggested that adults with a history of childhood sexual abuse may be more prone to produce false memories, little is known about the consequences of childhood neglect on basic memory processes. For this reason, the authors investigated how a group of women with a history of childhood emotional neglect (CEN) and diagnosed with recurrent Major Depressive Disorder (MDD) performed on the Deese–Roediger–McDermott paradigm in comparison to control groups. The results indicated that women with MDD and CEN were actually less prone to produce false memories relative to both women with MDD but no CEN and healthy women without MDD and any form of childhood maltreatment. These findings were explained in terms of the inability to extract/retrieve gist memories that support false recognition of critical lures, an explanation that seems to fit well with emerging MRI findings linking childhood neglect to reduced volume of brain regions associated to memory function.     

The corrective effects of warning on false memories in the DRM paradigm are limited to full attention conditions

Effects of attention control and forewarning on the activation and monitoring of experimentally induced false memories in the Deese/Roediger-McDermott paradigm were investigated in a young adult sample (N=77). We found that reducing the degree of attention during encoding led to a decrease in veridical recall and an increase in non-presented critical lure intrusions. This effect could not be counteracted by a forewarning instruction. However, these findings did not emerge in a (retrieval supportive) recognition task. It seems that divided attention increases false recall when attention control and forewarning have to compete for limited cognitive resources in a generative free recall as opposed to a retrieval supportive recognition task. Forewarning instructions do not always protect young adults against experimentally induced false memories.     

Trauma-related and neutral false memories in war-induced Posttraumatic Stress Disorder

Recent models of cognition in Posttraumatic Stress Disorder (PTSD) predict that trauma-related, but not neutral, processing should be differentially affected in these patients, compared to trauma-exposed controls. This study compared a group of 50 patients with PTSD related to the war in Bosnia and a group of 50 controls without PTSD but exposed to trauma from the war, using the DRM method to induce false memories for war-related and neutral critical lures. While the groups were equally susceptible to neutral critical lures, the PTSD group mistakenly recalled more war-related lures. Both false and correct recall were related more to depression than to self-rated trauma. Implications for accounts of false memories in terms of source-monitoring are discussed.