Recognition and recall in amnesics

Although there is considerable agreement that performance in direct memory tasks (e.g., recall, recognition) is more disrupted by amnesia than performance in indirect memory tasks (e.g., mirror reading, word completion), one may be able to further circumscribe the deficit within the domain of direct memory tasks. The present article explores whether recall is disproportionately disrupted by amnesia compared to recognition. If amnesia affects memory uniformly across different direct memory measures, recall of normal controls should not differ from the recall of amnesics when recognition scores of these two groups are equated. On the other hand, if recall is disproportionately disrupted, normal recall should be superior to amnesic recall even when recognition is equated. The present study equated amnesic recognition with that of controls by providing amnesics with 8 s of study time and normal subjects with 0.5 s. Amnesics with Korsakoff's syndrome, amnesics with other etiologies, and appropriate controls were examined. Normal recall was superior to amnesic recall even when no differences were found in recognition. The results further specify the selective nature of amnesia.     

The von Restorff effect and induced amnesia: production by manipulation of sound intensity.

When an outstanding item appears in an otherwise homogeneous list of items, the outstanding item is better remembered (the von Restorff effect), and items before and after it may be more poorly remembered (induced amnesia) than corresponding items in a control list. In the present experiments the outstanding item was a word presented as a loud shout among other words presented at normal conversational levels. In two experiments, large retrograde- and anterograde-induced amnesiae effects were demonstrated using a free-recall and a recognition task. In both experiments half of the subjects were told what to expect and were instructed to devise a strategy to eliminate induced amnesia. These instructions failed to eliminate the amnesiac effect. A third experiment was designed to demonstrate an empirical similarity between induced and clinical amnesia. In clinical retrograde (but not anterograde) amnesia, "lost" memories are sometimes recovered with time. Filled delays of 0, 30, or 120 sec interpolated between list presentation and recall demonstrated that induced retrograde amnesia disappeared at the longest delay but induced anterograde amnesia was unchanged. A fourth experiment eliminated some alternate interpretations of the effect.     

Can implicit measures detect source information in crime-related amnesia?

Participants who are asked to simulate amnesia for a mock crime have a weaker memory for this event when they have to give up their role as a feigner, than those who are not asked to feign memory loss. According to the source monitoring framework (SMF), this memory-undermining effect of simulating amnesia for a crime would be due to misattribution of the right source of information. However, we know that the content of self-generated information (e.g., feigned version of the crime) might be preserved and recognised over time as a result of elaborative cognitive processing. In the present study, we aimed to contrast these two explanations. We showed participants a mock crime video and we instructed them to either feign amnesia (simulators) or confess the mock crime (confessors). Next, a free recall memory test was administered. After one week, participants were asked to perform a personalised source monitoring task using the autobiographical Implicit Association Test (aIAT). As predicted, we found that simulators were able to discriminate the content of their self-generated feigned story of the crime from the original version. Moreover, simulators were quicker than confessors at the aIAT task. Practical and theoretical implications of our results are discussed.     

On the relationship between recall and recognition memory.

The relationship between recall and recognition has been a central topic for the study of memory. A test of alternative views about recall and recognition was arranged by studying amnesic patients. In amnesia, damage has occurred to a brain system important for declarative (conscious) memory, but skill learning, priming, and other forms of nonconscious memory are intact. Recall and recognition were found to be proportionately impaired in amnesic patients, and confidence ratings for the recognition judgments were commensurate with the level of impaired performance. The results are contrary to views that either recognition memory or associated confidence judgments are ordinarily supported significantly by nonconscious memory. The results favor the view that recall and recognition are related functions of declarative memory and equivalently dependent on the brain system damaged in amnesia.     

Traumatic memories and pseudomemories in posttraumatic stress disorder

Intrusive imagery was investigated in survivors of motor vehicle accidents with (a) posttraumatic stress disorder (PTSD) and accurate recall of the trauma, (b) PTSD and amnesia of the trauma, (c) no PTSD, or (d) control participants who simulated PTSD. Imagery was precipitated by presentation of an audiotape of a motor vehicle accident. Whereas the traumatic imagery of participants who had accurate recall of their trauma was consistent with third party accounts of the trauma, the imagery of amnesic participants was inconsistent with these accounts. Participants were then interviewed about cognitive and emotional aspects of their responses. All participants with PTSD and simulators reported similar levels of imagery detail, involuntariness, re-experiencing, and emotional response, and reported higher levels than participants with no PTSD. Findings are discussed in terms of cognitive and contextual factors that can mediate accurate and inaccurate traumatic imagery. © 1998 John Wiley & Sons, Ltd.     

Interidentity amnesia for neutral,episodic information in dissociative identity disorder

Interidentity amnesia is considered a hallmark of dissociative identity disorder (DID) in clinical practice. In this study, objective methods of testing episodic memory transfer between identities were used. Tests of both recall (interference paradigm) and recognition were used. A sample of 31 DID patients was included. Additionally, 50 control subjects participated, half functioning as normal controls and the other half simulating interidentity amnesia. Twenty-one patients subjectively reported complete one-way amnesia for the learning episode. However, objectively, neither recall nor recognition scores of patients were different from those of normal controls. It is suggested that clinical models of amnesia in DID may be specified to exclude episodic memory impairments for emotionally neutral material.     

The effects of repeating a recognition test in lorazepam-induced amnesia: Evidence for impaired contextual memory as a cause of amnesia

In two experiments, a recognition test for an earlier presented list was given twice in immediate succession (Test 1 and Test 2). On the hypothesis that anterograde amnesia for episodic memory involves a deficit in contextual memory, amnesic subjects should confuse familiarity with distractor items gained during Test 1 with familiarity gained during original list presentation. As a result, they should think that they recognize more items on Test 2. This will lower recognition efficiency in Test 2 by increasing false alarms rather than by reducing hits. For subjects with an amnesia induced by lorazepam, but not for control subjects, recognition efficiency was substantially reduced in Test 2 in both experiments. As predicted, this impairment was due to a large increase in false alarms, with no decrease in the number of hits. The impairment could not be explained by a difference in recognition level between lorazepam and control subjects on Test 1. These findings therefore support the contextual memory deficit hypothesis of anterograde amnesia. Their implications for understanding the relationship between recall and recognition in amnesia are discussed.     

Episodic memory, amnesia, and the hippocampal-anterior thalamic axis

By utilizing new information from both clinical and experimental (lesion, electrophysiological, and gene-activation) studies with animals, the anatomy underlying anterograde amnesia has been reformulated. The distinction between temporal lobe and diencephalic amnesia is of limited value in that a common feature of anterograde amnesia is damage to part of an "extended hippocampal system" comprising the hippocampus, the fornix, the mamillary bodies, and the anterior thalamic nuclei. This view, which can be traced back to Delay and Brion (1969), differs from other recent models in placing critical importance on the efferents from the hippocampus via the fornix to the diencephalon. These are necessary for the encoding and, hence, the effective subsequent recall of episodic memory. An additional feature of this hippocampal-anterior thalamic axis is the presence of projections back from the diencephalon to the temporal cortex and hippocampus that also support episodic memory. In contrast, this hippocampal system is not required for tests of item recognition that primarily tax familiarity judgements. Familiarity judgements reflect an independent process that depends on a distinct system involving the perirhinal cortex of the temporal lobe and the medial dorsal nucleus of the thalamus. In the large majority of amnesic cases both the hippocampal-anterior thalamic and the perirhinal-medial dorsal thalamic systems are compromised, leading to severe deficits in both recall and recognition.     

Intact retention in acute alcohol amnesia

Research on alcohol amnesia has focused on memory processes that are disrupted during intoxication. The present experiment examined the possibility that certain memory processes might be resistant to the amnesic effects of alcohol. Intoxicated and sober subjects studied a list of 29 words. They were then given one of three different retention tests: free recall, identification of degraded words based on the procedure used by Warrington and Weiskrantz (1970), and yes/no recognition. As expected, free recall was significantly impaired by alcohol intoxication. In contrast, in the identification test, intoxicated subjects benefited to the same degree as sober subjects from prior exposure to the items. The two groups did not differ in immediate recognition memory. The results of the free-recall and identification tasks are similar to findings with chronic amnesic patients and suggest that perceptual fluency is not affected by alcohol, whereas elaborative processes supporting recall are particularly sensitive to disruption during intoxication. The failure to find recognition impairment at the level of intoxication used in this study distinguishes temporary alcohol amnesia from chronic amnesia.     

Autonomic and behavioral evidence of "implicit" memory in amnesia

A profoundly amnesic patient with a left retrosplenial-fornix lesion was tested on a recognition task that evaluated both verbal and electrodermal aspects of new learning. In addition, "implicit memory" tasks (mirror reading and perceptual identification) were given. The patient displayed strong evidence of learning on all tasks although the results of this learning were not represented in explicit recall or recognition. These findings suggest that autonomic as well as behavioral evidence can index spared memory functions in amnesia. The specific meaning of electrodermal recognition and its possible place in the distinction between implicit and explicit memory is discussed.     

Does feigning amnesia impair subsequent recall?

Defendants who are accused of serious crimes sometimes feign amnesia to evade criminal responsibility. Previous research has suggested that feigning amnesia might impair subsequent recall. In two experiments, participants read and heard a story about a central character, described as “you,” who was responsible for the death of either a puppy (Experiment 1) or a friend (Experiment 2). On free and cued recall tests immediately after the story, participants who had feigned amnesia recalled less than did participants who had recalled accurately. One week later, when all participants recalled accurately, participants who had previously feigned amnesia still performed worse than did participants who had recalled accurately both times. However, the participants who had formerly feigned amnesia did not perform worse than did a control group who had received only the delayed recall tests. Our results suggest that a “feigned amnesia effect” may reflect nothing more than differential practice at recall. Feigning amnesia for a crime need not impair memory for that crime when a person later seeks to remember accurately.     

Public events and flashbulb memories in Parkinson's disease

Public events and Flashbulb memories were investigated in 12 non-demented patients with Parkinson's disease (PD) and 12 controls. Knowledge of public events and flashbulbs memories were assessed using a Famous Events Test (EVE 30). Contributions of semantic, episodic, as well as executive functioning and anterograde memory were examined. Results primarily showed that the performances of patients with PD were lower than these of controls in 4 tasks: free recall, specific questions, dating events and date recognition. They also had difficulties in finding the temporal order of 8 events. In contrast, the PD group benefited from events recognition themselves to the same extent as the controls. Secondly, the recall of flashbulb memories (FBM) was lower in the PD group than in the controls. Finally, correlations appeared in PD between the detailed recall of the events with the "recall" abilities of the MATTIS scale, possibly reflect an impairment in rebuilding memories. A positive correlation is also observed with the initiation score of the MATTIS (executive component), suggesting that the difficulties of rebuilding can be related to a dysfunction in accessing information because of a certain degree of frontal amnesia.     

Childhood amnesia: a conceptualization in cognitive-psychological terms

Childhood amnesia is defined operationally as the forgetting of early life events to a significantly greater degree than is accounted for by "normal" forgetting, which is an increasing recall decrement as time since occurrence increases. Three cognitive processes and their developmental changes are discussed which, when considered with psychodynamic factors, may broaden the understanding of childhood amnesia. It is argued that psychoanalytic theory and technique can benefit from the research and methods of cognitive psychology.     

Retrograde Amnesia after ECT. An Attempt to Demonstrate Reminder-effects in Humans

In a study of the retrograde amnesic effect of bilateral ECT, twelve patients were subjects in a repeated measures design. Both verbal and nonverbal materials were used and retention was tested with different methods: Yes-no recognition, forced-choice recognition and recall cued by initial letters. The absolute amount of retrograde amnesia was small; there seemed to be no difference between verbal and nonverbal materials, and cueing with initial letters was not found to be an effective method of reducing amnesia.     

An experimental investigation of the misinformation effect in crime-related amnesia claims

Research suggests that both internal (i.e., lying) and external (i.e., misinformation) factors can affect memory for a crime. We aimed to explore the effects of post-event misinformation on crime-related amnesia claims. We showed participants a mock crime and asked them to either simulate amnesia (simulators) or confess to it (confessors). Next, some participants were provided with misinformation. Finally, all participants were requested to genuinely recollect the crime. Overall, simulators reported less correct information than confessors. Moreover, these two groups were equally vulnerable to misinformation. In addition, exploratory analyses on strategies adopted by simulators revealed that those who previously, mostly omitted information while simulating amnesia exhibited the lowest amount of correct details. Simulators who instead used a mixed strategy disclosed more fabricated memory errors. Findings suggest that legal professionals and jurors should take into account that even offenders, irrespective of confessing or simulating memory loss for a crime, can be susceptible to post-event misinformation.     

Remote memory in a patient with circumscribed amnesia

It has been suggested that extensive and severe remote memory loss is not a component of a circumscribed amnesic syndrome but may be attributable to problem solving and retrieval deficiencies associated with the frontal lobe damage which is present in some amnesic patients. In order to assess this notion, retrograde amnesia was studied in a patient, W.H., who had no apparent cortical damage revealed by radiological examination, and who evidenced no major cognitive deficiency other than amnesia. Regardless of whether remote memory was measured by recall or recognition procedures, patient W.H. exhibited impaired memory for information from the 1960s, 1970s, and 1980s, but was unimpaired in retrieving information from the 1940s and 1950s. These results demonstrate that retrograde amnesia can occur in patients who have a circumscribed memory deficit.     

Outstanding memories: the positive and negative effects of nudes on memory

A picture of a nude isolated in a series of pictures of clothed models was quite memorable, but when compared with a clothed picture, the nude impaired memory for background picture derails as well as pictures immediately following the nude (anterograde amnesia). Recall of details given picture-gist recall, as well as recognition of person details, were equivalent in the clothed and nude conditions. A clothed picture isolated in a series of nudes did not hurt memory for background information, nor did it produce anterograde amnesia. Apparently, distinctiveness supports good memory for the gist of the nude or clothed pictures. However, distinctiveness is not responsible for the anterograde amnesia and poor memory for background details found with nudes.     

The relationship between induced emotional arousal and amnesia

An experiment was conducted to test a hypothesis emanating from a similarity in data pattern between studies on amnesia and studies on the effects of arousal on memory. The hypothesis was that arousal and amnesia might be related, or more precisely, that amnesia induced in the laboratory might be mediated by high levels of arousal. Subjects in this experiment were presented with a thematic, short story in pictorial form. One version of the story consisted of a traumatic, arousal-inducing event placed between neutral events. A second version of the story contained the same neutral events in the beginning and the end, but also a neutral event in the middle. Palmar skin conductance, heart rate, and subjective self-ratings were used to determine that the manipulation made had caused different degrees of emotional arousal for the two groups of subjects presented with the different versions of the story. The methods used to determine memory performance were recall and recognition. The data obtained indicate that amnesia induced in the laboratory is mediated by emotional arousal in terms of concepts of attention and reconstruction.