Memory illusions: false recall and recognition in adults with Asperger's syndrome

As persons on the autistic spectrum are known not to use semantic features of word lists to aid recall, they might show diminished susceptibility to illusory memories that typically occur with lists of associated items. Alternatively, since such individuals also have poor source monitoring, they might show greater susceptibility. The authors found that adults with Asperger's syndrome (n = 10) recalled similar proportions of a nonpresented strong associate of the study list items, compared with controls (n = 15). In Experiment 2, rates of true and false recognition of study list associates did not differ significantly between Asperger (n = 10) and control (n = 10) participants. Moreover, the Asperger participants made fewer remember and more know judgments than controls for veridical but not for false recognitions. Thus, deficits found in some aspects of memory in people with Asperger's syndrome do not affect their susceptibility to memory illusions.     

False memories in women with self-reported childhood sexual abuse: an empirical study

Although controversy exists about the validity of memories of childhood abuse, little is known about memory function in individuals reporting childhood abuse. This study assessed memories for previously presented words, including the capacity for false memory of critical lures not actually present in the word list, in 63 subjects, including abused women with posttraumatic stress disorder (PTSD), abused women without PTSD, and men and women without abuse or PTSD. Abused women with PTSD had a higher frequency of false recognition memory of critical lures (95%) than abused women without PTSD (78%), nonabused women without PTSD (79%), or nonabused men without PTSD (86%). PTSD women also showed poorer memory for studied words and increased insertions of non-studied words other than critical lures. These findings are consistent with a broad range of memory alterations in abused women with PTSD.     

What is the connection between true and false memories? The differential roles of interitem associations in recall and recognition.

Veridical memory for presented list words and false memory for nonpresented but related items were tested using the Deese/Roediger and McDermott paradigm. The strength and density of preexisting connections among the list words, and from the list words to the critical items, were manipulated. The likelihood of producing false memories in free recall varied with the strength of connections from the list words to the critical items but was inversely related to the density of the interconnections among the list words. In contrast, veridical recall of list words was positively related to the density of the interconnections. A final recognition test showed that both false and veridical memories were more likely when the list words were more densely interconnected. The results are discussed in terms of an associative model of memory, Processing Implicit and Explicit Representations (PIER 2) that describes the influence of implicitly activated preexisting information on memory performance.     

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.     

Caffeine increases false memory in nonhabitual consumers

Insight into caffeine's equivocal effects on memory can be derived from work suggesting both emotional arousal and psychosocial stress increase false memory rates without increasing veridical memory. This study investigated how a range of caffeine doses affect veridical and false memory formation in nonhabitual consumers. A double-blind, repeated-measures design with caffeine (0 mg, 100 mg, 200 mg, 400 mg caffeine) was used to examine memory using the Deese-Roediger-McDermott (DRM) paradigm. Results showed that caffeine modulated arousal levels, peaking at 200 mg and returning to near baseline levels at 400 mg. Main effects of caffeine demonstrated higher critical lure recall and recognition ratings (i.e., false memory) as a function of dose, again peaking at 200 mg. Those who showed the highest arousal increases as a function of caffeine also tended to produce the highest false recall and recognition rates. Veridical memory was not affected. Results demonstrate that consumption of as little as 100 mg of caffeine elicits reliable inverted-U shape changes in arousal and, in turn, false memories in individuals who do not habitually consume caffeine.     

The effects of social pressure on false memories

The present experiments were designed to examine the effects of social pressure on false memories. Participants studied lists created to elicit false memories and then worked in conjunction with virtual confederates on a recognition memory task. In Experiment 1, participants worked with one or two confederates to complete multiple study-test trials. On the group tests, participants were implicitly pressured to recognize words that did not appear on the studied lists. Experiment 2 was implemented similarly, but utilized a presumably more difficult recognition test involving one long study phase followed by one long test phase. After the purported group tests in both experiments, participants completed surprise individual recognition tests. In both experiments, social pressure influenced participants' responses on group recognition tests and subsequent individual recognition tests. Furthermore, the results indicated that social pressure affected both veridical memories and false memories.     

False memory in a short-term memory task

The Deese/Roediger-McDermott (DRM; Roediger & McDermott, 1995) paradigm reliably elicits false memories for critical nonpresented words in recognition tasks. The present studies used a Sternberg (1966) task with DRM lists to determine whether false memories occur in short-term memory tasks and to assess the contribution of latency data in the measurement of false memories. Subjects studied three, five, or seven items from DRM lists and responded to a single probe (studied or nonstudied). In both experiments, critical lures were falsely recognized more often than nonpresented weak associates. Latency data indicated that correct rejections of critical lures were slower than correct rejections of weakly related items at all set sizes. False alarms to critical lures were slower than hits to list items. Latency data can distinguish veridical and false memories in a short-term memory task. Results are discussed in terms of activation-monitoring models of false memory.     

Are trauma victims susceptible to "false memories"?

Laboratory studies using word-list paradigms have provided evidence that nontraumatized individuals falsely recall or recognize events that never occurred. In the present study, H. L. Roediger and K. B. McDermott's false-memory paradigm (1995) was utilized to examine possible source monitoring deficits in individuals with PTSD. Traumatized individuals with PTSD were compared with traumatized individuals without PTSD and with nontraumatized control participants. Participants heard lists of related words (e.g., bed, night) that were associates of a critical nonpresented word (e.g., sleep) and were given immediate free recall and later recognition tests. Traumatized participants with and without PTSD generated more false recalls of critical nonpresented words than did nontraumatized participants. False recall was related to trait anxiety and PTSD severity. The results are consistent with a general source-monitoring deficit in trauma-exposed individuals.     

Traumatic memories of war veterans: not so special after all

Several authors have argued that traumatic experiences are processed and remembered in a qualitatively different way from neutral events. To investigate this issue, we interviewed 121 Croatian war veterans diagnosed with posttraumatic stress disorder (PTSD) about amnesia, intrusions (i.e., flashbacks and nightmares), and the sensory qualities of their most horrific war memories. Additionally, they completed a self-report scale measuring dissociative experiences. In contrast to what one would expect on the basis of theories emphasizing the special status of traumatic memories, amnesia, and high frequency intrusions were not particularly typical for our sample of traumatized individuals. Moreover, traumatic memories were not qualitatively different from neutral memories with respect to their stability and sensory qualities. The severity of PTSD symptoms was not significantly correlated with dissociative experiences. Our findings do not support the existence of special memory mechanisms that are unique to experiencing traumatic events.     

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.     

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.     

Overgeneral memory extends to pictorial retrieval cues and correlates with cognitive features in posttraumatic stress disorder

Individuals with posttraumatic stress disorder (PTSD) show overgeneral memory (OGM) when retrieving autobiographical memories to word cues. We investigated whether OGM extends to picture cues and whether it is related to PTSD symptoms and cognitions. Trauma survivors with (n = 29) and without (n = 26) PTSD completed the standard Autobiographical Memory Test (AMT) and a novel picture version. Compared to the no-PTSD group, the PTSD group showed OGM in both test versions. Pictures facilitated specific memory retrieval, but this effect was no longer significant when verbal intelligence or depressive symptoms were controlled. OGM correlated with PTSD symptoms and perceived self-change; with intrusive memories, their perceived "nowness," responses to intrusions (thought suppression, rumination, dissociation), and negative interpretations of symptoms.     

Remembering Words Never Presented: False Memory Effects in Dementia of the Alzheimer Type

Thirty-five young adults, 35 older adults and 29 individuals with dementia of the Alzheimer’s type studied lists of semantically related words (e.g., thread, pin, sewing) that converged on a non-presented lure (needle). Compared to the young adults, older adults remembered (recall and recognition tests) fewer studied items but falsely remembered more non-presented lures. Memory for studied items was lower in the DAT group compared to normal elders. The DAT group did recall some non-presented lures, although unlike the older adults, recall of non-presented lures was not elevated compared to veridical memory. Similar to the normal elders, the DAT group showed increased susceptibility to false recognition of non-presented lures. Susceptibility to false recognition did not vary as a function of disease severity.     

How similar is false recognition to veridical recognition objectively and subjectively?

Three recognition memory experiments were conducted using modified Deese-Roediger-McDermott (DRM) and DRM paradigms. In Experiment 1, the reaction time (RT) of the false alarms to critical nonpresented words (false memory) was compared with the RT of hits to the critical presented words and with the RT of hits to the studied list words (true memory). The RT of the false alarms to the critical nonpresented words was significantly longer than that of the hits to the critical words and than that of the studied list words. In Experiment 2, in addition to RT, participants' confidence level was measured on a 4-point scale for a yes or no response. Confidence rating was significantly higher for the hits to the critical presented words and to the list words than for the false alarms to the critical non-presented words. Experiment 3 further showed that how similar false memory experience was to that of true memory was a function of retention size (number of lists of words retained in memory). In all three experiments, the participants' recognition RTs distinguished false memory from veridical memory, and in Experiments 2 and 3, so did their confidence ratings. Therefore, false memory and veridical memory differ at both the objective and the subjective levels. The results are consistent with a single familiarity dimension model of recognition memory.     

Dividing attention lowers children's but increases adults' false memories

The present study examined the impact of divided attention on children's and adults' neutral and negative true and false memories in a standard Deese/Roediger-McDermott paradigm. Children (7- and 11-year-olds; n = 126) and adults (n = 52) received 5 neutral and 5 negative Deese/Roediger-McDermott word lists; half of each group also received a divided attention task. The results showed that divided attention affected children's and adults' false memory levels differently but did not alter true memory differently. Our results revealed a developmental shift in that divided attention lowered children's false memory rates but increased adults' false memory rates, regardless of the nature of the material (i.e., neutral or negative). Our study indicates that manipulations that target conscious processing (e.g., divided attention) result in marked qualitative and quantitative differences between children's and adults' false memories but not true memories.     

The role of associative strength in children's false memory illusions

The effects of associative strength on rates of 7- and 11-year-old children's true and false memories were examined when category and Deese-Roediger-McDermott (DRM) lists were used to cue the same critical lure. Backward associative strength (BAS) was varied such that the category and DRM lists had the same strength (DRM=category), DRM lists had more BAS (DRM>category), or category lists had more BAS (DRM<category). If BAS drives children's false memories then BAS, not the type of relation across items in a list, should determine false memory production. The results confirmed this prediction using both recall and recognition measures: (1) both true and false memories increased with age, (2) true memory was better for category than DRM lists but there were no differences for false memory, and (3) at all ages, false memories varied predictably with changes in BAS but were unaffected by list-type manipulations. These findings are discussed in the context of models of false memory development.     

Serial position-dependent false memory effects*

ABSTRACT

Evidence for false recognition within seconds of encoding suggests that semantic-associative influences are not restricted to long-term memory, consistent with unitary memory accounts but contrary to dual store models. The present study sought further relevant evidence using a modified free recall converging associates task where participants studied 12-item lists composed of 3 semantically distinct quartets (sublists) related to a separate, non-presented theme word (i.e., words 1–4/theme1, 5–8/theme2, and 9–12/theme3). This list construction permits assessment of false recall errors from each sublist, and, particularly, the primacy and recency sublists that have been linked to long- and short-term memory stores. Experiment 1 tested immediate free recall for items. Associative false memories were evident from all sublists, however, significantly less so from the recent sublist, which also showed the highest levels of veridical memory. By inserting a brief (3?s) distractor prior to recall, Experiment 2 selectively reduced veridical memory and increased false memory for the recent sublist while leaving the primacy sublist unaffected. These recall results converge with prior evidence indicating the immediacy of false recognition, and can be understood within a unitary framework where the differential availability of verbatim features and gist-based cues affect memory for primacy and recency sublists.     

Psychopathic personality traits are linked to reduced false memories for negative events

Individuals scoring high on psychopathic personality traits process emotional material to a different extent than individuals with few psychopathic traits. Evidence exists that these individuals have impaired emotional memory. The question arises whether this emotional memory impairment has ramifications for the production of emotional false memories. In the present study, we investigated the production of false and true memories for emotional events in a community sample (N = 120) of individuals varying in psychopathic traits (evaluated with the Psychopathic Personality Inventory–Revised [PPI-R] questionnaire). The fearless dominance (FD) component of psychopathy interacted with the emotional impact of to-be-remembered events in the production of false memories, showing fewer negative false memories with increasing levels of FD. At the subjective level, negative false memories were not perceived as vivid memory experiences in high FD individuals. Concerning true memories, higher scores in cold-heartedness were related to fewer true memories for neutral and negative (but not positive) events. These results show that individuals with high psychopathy traits – in particular, FD – do not have a general emotional memory impairment but they process negative material in a different way than individuals with low psychopathic traits and thus are less susceptible to producing false memories for negative events.     

Overgeneral autobiographical memory recollection in Iranian combat veterans with posttraumatic stress disorder

This study examined the recollection of autobiographical material in memory among Iranian military veterans with and without posttraumatic stress disorder (PTSD), and healthy non-trauma-exposed control subjects. Participants completed the Autobiographical Memory Test, Autobiographical Memory Interview (counterbalanced), Impact of Event Scale-Revised, Beck Depression Inventory-II, Wechsler Memory Scale-III and Wechsler Adult Intelligence Scale-Revised. The PTSD group generated fewer specific episodic and semantic details of autobiographical memory compared to the non-PTSD and control groups. Working memory did not significantly moderate the relationship between PTSD diagnosis and reduced autobiographical memory specificity but did moderate the relationship between PTSD diagnosis and semantic recall; semantic memory recall was not significantly related to working memory ability for those with PTSD but was related to working memory ability for trauma survivors without PTSD. While the data provide some support for the expectation that higher working memory ability is associated with an increased ability to retrieve specific memories (i.e. semantic memory recall in those without PTSD), the findings are also consistent with the view that for those with PTSD the demands on working memory required for affect regulation cancel out this influence of working memory in augmenting access to specific memories.     

Fantasy proneness, but not self-reported trauma is related to DRM performance of women reporting recovered memories of childhood sexual abuse

Extending a strategy previously used by , we administered a neutral and a trauma-related version of the Deese-Roediger-McDermott paradigm to a sample of women reporting recovered (n=23) or repressed memories (n=16) of childhood sexual abuse (CSA), women reporting having always remembered their abuse (n=55), and women reporting no history of abuse (n=20). We found that individuals reporting recovered memories of CSA are more prone than other participants to falsely recalling and recognizing neutral words that were never presented. Moreover, our study is the first to show that this finding even held when trauma-related material was involved. Correlational analyses revealed that fantasy proneness, but not self-reported traumatic experiences and dissociative symptoms were related to false recall and false recognition.