Fluency versus conscious recollection in category-production performance: the performance of schizophrenic patients

The purpose of this study was to investigate the relative contribution in schizophrenics of automatic processes (fluency) and conscious processes (conscious recollection) for the control of preencoded material in category production tasks. In one condition (Exclusion condition), subjects were told specifically not to produce previously presented words during the category-production task. This condition was compared with a standard category-production task in which subjects were told to produce the six first words that came to mind for a semantic category (Inclusion condition). In the inclusion condition, the effects of conscious control and automatic processes operated in the same direction, whereas in the exclusion condition automatic influences and conscious control were opposed. A recognition task followed the category-production tasks. Since the exclusion condition required conscious control of encoded items, we hypothesized that schizophrenic patients would be less able than control subjects to avoid producing study list items. These results indicated that schizophrenics' performance differed from these of control subjects in the exclusion condition but not in inclusion condition. Recognition performance was similar in both the schizophrenic and the control groups. These results suggest a defective conscious control in schizophrenic patients and confirm the data from the literature on explicit memory in these patients.     

Implicit and explicit memory for new associations in normal and amnesic subjects

Two experiments examined whether repetition priming effects on a word completion task are influenced by new associations between unrelated word pairs that were established during a single study trial. On the word completion task, subjects were presented with the initial three letters of the response words from the study list pairs and they completed these fragments with the first words that came to mind. The fragments were shown either with the paired words from the study list (same context) or with other words (different context). Both experiments showed a larger priming effect in the same-context condition than in the different-context condition, but only with a study task that required elaborative processing of the word pairs. This effect was observed with college students and amnesic patients, suggesting that word completion performance is mediated by implicit memory for new associations that is independent of explicit recollection.     

Memory strategies with brain damage

The ability of anterograde amnesics with and without a history of alcoholism and patients with frontal lobe damage to think about memory, memorizing, and remembering was assessed. Alcoholic Korsakoffs' and frontal lobe patients' knowledge and use of memory strategies was deficient when compared with controls whereas nonalcoholic amnesics' was not. The use of the categorization mnemonic was assessed in a verbal learning experiment. Frontal lobe patients failed to spontaneously categorize a categorizable word list when trying to memorize it. Nevertheless, when forced to categorize the list, they benefited from the imposed structure. Nonalcoholic amnesics spontaneously categorized the list and benefited from the resulting organization.     

The use of indirect memory tests to assess malingered amnesia: a study of metamemory.

Many techniques have been suggested for identifying criminal suspects who are simulating amnesia for the events surrounding a crime. The present research focuses on indirect memory tests as a potential means of discriminating between those who genuinely suffer from amnesia and those who are simulating. Subjects studied a list of words and subsequently performed either a word completion or a fragment completion task. Under normal indirect test instructions, typical priming effects were observed. When subjects were motivated to simulate amnesia for the list, target completion rates were consistently, and sometimes reliably, below baseline completion rates. This finding is contrary to the performance of genuine amnesics, whose performance on indirect tests typically mirrors that of normal subjects. Indirect tests may prove useful in discriminating genuine and simulating amnesics.     

Amnesics Have a Disproportionately Severe Memopry Deficit for Interactive Context

Two experiments were used to compare the recognition memory of amnesic and normal subjects for intentionally encoded words (targets) and for incidentally encoded words that were meaningfully related to the targets and presented at the same time (interactive context). In both experiments the target recognition of the two groups was matched at a high level by presenting the amnesics with much shorter lists of words to remember. Experiment 1 compared 20 amnesics and their matched controls and showed that whereas the amnesics' recognition of the target words did not benefit significantly when they were presented together with their interactive context words (relative to their recognition when the target words were presented alone), that of the controls did. Experiment 2 compared 14 amnesics and their matched controls and showed that when patients and their controls were matched on their target word recognition in isolation, then the patients still showed worse recognition for the interactive context words. These effects were not found only in Korsakoff patients, and their size did not correlate with behavioural measures of frontal-lobe damage. It is concluded that amnesics may be more impaired at recognizing incidentally encoded interactive context than they are at recognizing target material, and this deficit may be an essential feature of the syndrome.     

Automatic processing influences free recall: converging evidence from the process dissociation procedure and remember-know judgments

Dual-process theories of retrieval suggest that controlled and automatic processing contribute to memory performance. Free recall tests are often considered pure measures of recollection, assessing only the controlled process. We report two experiments demonstrating that automatic processes also influence free recall. Experiment 1 used inclusion and exclusion tasks to estimate recollection and automaticity in free recall, adopting a new variant of the process dissociation procedure. Dividing attention during study selectively reduced the recollection estimate but did not affect the automatic component. In Experiment 2, we replicated the results of Experiment 1, and subjects additionally reported remember–know–guess judgments during recall in the inclusion condition. In the latter task, dividing attention during study reduced remember judgments for studied items, but know responses were unaffected. Results from both methods indicated that free recall is partly driven by automatic processes. Thus, we conclude that retrieval in free recall tests is not driven solely by conscious recollection (or remembering) but also by automatic influences of the same sort believed to drive priming on implicit memory tests. Sometimes items come to mind without volition in free recall.     

A systematic investigation of same and cross modality priming using written and spoken responses

Effects of presentation modality and response format were investigated using visual and auditory versions of the word stem completion task. Study presentation conditions (visual, auditory, non-studied) were manipulated within participants, while test conditions (visual/written, visual/spoken, auditory/written, auditory/spoken, recall-only) were manipulated between participants. Results showed evidence for same modality and cross modality priming on all four word stem completion tasks. Words from the visual study list led to comparable levels of priming across all test conditions. In contrast, words from the auditory study list led to relatively low levels of priming in the visual/written test condition and high levels of priming in the auditory/spoken test condition. Response format was found to influence priming performance following auditory study in particular. The findings confirm and extend previous research and suggest that, for implicit memory studies that require auditory presentation, it may be especially beneficial to use spoken rather than written responses.     

Increasing the salience of fluency cues does not reduce the recognition memory impairment in Alzheimer's disease!

In Alzheimer's disease (AD), it is now well established that recollection is impaired from the beginning of the disease, whereas findings are less clear concerning familiarity. One of the most important mechanisms underlying familiarity is the sense of familiarity driven by processing fluency. In this study, we attempted to attenuate recognition memory deficits in AD by maximizing the salience of fluency cues in two conditions of a recognition memory task. In one condition, targets and foils have been created from the same pool of letters (Overlap condition). In a second condition, targets and foils have been derived from two separate pools of letters (No‐Overlap condition), promoting the use of letter‐driven visual and phonetic fluency. Targets and foils were low‐frequency words. The memory tasks were performed by 15 patients with AD and 16 healthy controls. Both groups improved their memory performance in the No‐Overlap condition compared to the Overlap condition. Patients with AD were able to use fluency cues during recognition memory as older adults did, but this did not allow to compensate for dysfunction of recognition memory processes.     

Cued recall in anterograde amnesia

After a single presentation of a word list, normal subjects exhibited better retention when prompted with semantic cues than with rhyme or letter cues. Alcoholic Korsakoff patients, patients receiving electroconvulsive therapy (ECT), and the patient N.A. exhibited impaired retention and, unlike control subjects, did not exhibit an advantage of semantic cues over letter and rhyme cues. Two experimental manipulations designed to equate the level of performance of amnesics and controls indicated that these amnesias could be understood as a reflection of weak memory strength that results from deficiencies in initial learning and retention. In addition, alcoholic Korsakoff patients appeared to have greater difficulty utilizing semantic cues than patients receiving ECT or patient N.A.     

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.     

Implicit and explicit memory in young and older adults

In three experiments, young and older adults were compared on both implicit and explicit memory tasks. The size of repetition priming effects in word completion and in perceptual identification tasks did not differ reliably across ages. However, age-related decrements in performance were obtained in free recall, cued recall, and recognition. These results, similar to those observed in amnesics, suggest that older adults are impaired on tasks which require conscious recollection but that memory which depends on automatic activation processes in relatively unaffected by age.     

流畅性对再认的影响:实验证据及理论解释

流畅性可以影响再认,而且仅影响熟悉性加工的观点已得到大量研究的证实。近年一些研究者采用掩蔽启动范式并结合修改的R/K范式、独立判断的R/K范式等实验范式,操控测验项目的流畅性,发现流畅性影响的可能是猜测或者回想加工,因而质疑这个结论。为解释流畅性对再认的影响,流畅性归因理论侧重对流畅性的归因、冲突-归因理论侧重期待流畅性和实际流畅性之间的冲突、预激活-适应模型侧重启动刺激引起的神经活动激活或适应、线索-学习理论侧重流畅性线索的有效性。未来研究应关注流畅性对来源和联结记忆的影响,并考察流畅性对再认的影响在不同年龄人群或遗忘症人群中的表现是否一致。     

List strength effect without list length effect in recognition memory

The study of list length effects (adding items to a list affects memory for the other items) and list strength effects (strengthening some items in a list affects memory for the nonstrengthened items) is important to constrain models of memory. In recognition memory, a list length effect is generally found, whereas a list strength effect is not. Using the switched-plurality procedure in an old-new recognition task (e.g., study banana; test bananas), we found the opposite pattern. Length manipulations caused no change in memory performance, whereas strength manipulations did. The list strength effect was found when recollection was likely to operate at test (with switched-plurality lures). When recollection was unlikely to operate (with unrelated lures), the strength effect disappeared. The result was observed using both a size judgement task (which has previously produced positive list strength effects) and a pleasantness judgement task (which has not yielded list strength effects before).     

Production and Identification Repetition Priming in AmnesticMild Cognitive Impairment

ABSTRACT

The experiment reported here examined implicit memory function, as measured through repetition priming, in amnestic mild cognitive impairment (MCI) to examine whether impairments exist in this aspect of memory function. Young adults, healthy older controls, Alzheimer's disease patients, and MCI participants were asked to perform two types of implicit memory tests (word stem completion and threshold identification repetition priming tasks), as well as a recognition test for studied items. As expected, young adults performed better than the other participants on the recognition test and the word stem completion task; there was equivalent priming across groups on the word identification task. While both the older control and MCI participants showed lower levels of priming on the word stem completion task relative to the young adults, the magnitude of priming was equivalent for these two groups, and reliably greater than that of the dementia participants. These results suggest that not all aspects of memory function are impaired in MCI relative to healthy aging.     

Competition between automatic and controlled processes

We investigated the competition between automatic and controlled processes in a word stem completion task. Prime-display duration and the prime-target interval were manipulated. On each trial a masked prime was displayed briefly, followed either immediately or after a delay by a word stem. The subjects were required to complete each stem with the first word that came to mind, to report any prime they could identify, and not to give as completion any identified prime. By the assumption that automatic processes require less stimulus input and can be completed faster than consciously controlled processes we expected a stronger performance contribution from automatic processes with the shorter prime-display durations and in the immediate stems condition. The results confirmed this expectation. The findings highlight that consciously controlled processes require more time to run their course than unconscious automatic processes.     

The cerebellum and language: Evidence from patients with cerebellar degeneration

Clinical and imaging studies suggest that the cerebellum is involved in language tasks, but the extent to which slowed language production in cerebellar patients contributes to their poor performance on these tasks is not clear. We explored this relationship in 18 patients with cerebellar degeneration and 16 healthy controls who completed measures of verbal fluency (phonemic and semantic), word stem completion, and oral naming speed. Cerebellar patients showed significantly slower response times when naming common nouns, which correlated with their degree of motor impairment. Patients were significantly impaired on both phonemic and semantic fluency measures compared to controls (p < 0.001), even when naming speed was entered as a covariate (p = 0.03). On the word stem completion task, patients were significantly less accurate (p < 0.001), had more errors due to non-responses (p = 0.008), and were slower to respond (p = 0.036) than controls; group effects were significant for overall accuracy, but not response time, when the effects of naming speed were covaried (p = 0.014). These findings suggest that cerebellar patients’ poorer performance on language tasks cannot be explained solely by slower language production, and that the integrity of cerebellar-prefrontal loops might underlie poorer performance on measures of executive function in cerebellar patients.     

List strength effect without list length effect in recognition memory

The study of list length effects (adding items to a list affects memory for the other items) and list strength effects (strengthening some items in a list affects memory for the nonstrengthened items) is important to constrain models of memory. In recognition memory, a list length effect is generally found, whereas a list strength effect is not. Using the switched-plurality procedure in an old–new recognition task (e.g., study banana; test bananas), we found the opposite pattern. Length manipulations caused no change in memory performance, whereas strength manipulations did. The list strength effect was found when recollection was likely to operate at test (with switched-plurality lures). When recollection was unlikely to operate (with unrelated lures), the strength effect disappeared. The result was observed using both a size judgement task (which has previously produced positive list strength effects) and a pleasantness judgement task (which has not yielded list strength effects before).     

Mind wandering and retrieval from episodic memory: a pilot event-related potential study

The present study investigated the effects of mind wandering (task-unrelated thought) on the subcomponents of episodic memory as reflected by event-related potentials (ERPs). Specifically, individual differences in the pattern of ERP episodic 'old/new' effects (left-parietal, right-frontal and central-negativity effects) were examined across groups of participants experiencing either high or low frequencies of task-unrelated thought during encoding. Twenty participants studied lists of words and line drawings in one of two contexts (red versus green coloured boxes). At test, participants discriminated between target (old words or line drawings presented in one colour) and nontargets (old items from the other colour and new items). On completion of the memory task, participants completed the 'thinking' component of the Dundee Stress State Questionnaire to provide a retrospective measure of task-unrelated thought. Behavioural data indicated that irrespective of the presence of task-unrelated thought, participants were able to complete the memory task equally well. However, an analysis of ERPs across High and Low task-unrelated thought groups revealed differences in retrieval strategy. Those individuals with infrequent episodes of task-unrelated thought at study used a 'pure' recollection strategy (left-parietal effect only). Conversely, those participants experiencing frequent episodes of task-unrelated thought were unable to recollect the stimuli with ease, as indexed by a diminished parietal effect. As a consequence, these participants employed additional strategic processes for task completion, as indexed by an elevated amplitude of central negativity effects. These data are consistent with the decoupling hypothesis of mind wandering which suggests impaired recollection when attention becomes directed away from the task.     

Spatial Location Memory in Amnesia: Binding Item and Location Information Under Incidental and Intentional Encoding Conditions

Items located within an array were presented to alcoholic Korsakoff and nonalcoholic mixed-etiology amnesics and to alcoholic and normal controls. Recognition memory for the locations of items was tested after incidental and intentional encoding. When equated on item recognition, neither Korsakoff amnesics nor alcoholic controls benefited from intentional, relative to incidental, encoding instructions. Furthermore, Korsakoff amnesics showed neither disproportionately impaired incidental nor intentional location recognition memory relative to alcoholic controls. In contrast, mixed-etiology amnesics profited significantly from intentional location acquisition relative to incidental instructions, and were impaired somewhat in incidental, but not intentional, location memory relative to normal controls. We discuss these data in relation to Mayes' (1992) contextual memory deficit hypothesis and Hirst's (1982) automatic encoding deficit account, and propose an alternative framework in which the location memory deficit observed in mixed-etiology amnesics is interpreted as a disruption to the ability to bind item and location information.     

Production and identification repetition priming in amnestic mild cognitive impairment

The experiment reported here examined implicit memory function, as measured through repetition priming, in amnestic mild cognitive impairment (MCI) to examine whether impairments exist in this aspect of memory function. Young adults, healthy older controls, Alzheimer's disease patients, and MCI participants were asked to perform two types of implicit memory tests (word stem completion and threshold identification repetition priming tasks), as well as a recognition test for studied items. As expected, young adults performed better than the other participants on the recognition test and the word stem completion task; there was equivalent priming across groups on the word identification task. While both the older control and MCI participants showed lower levels of priming on the word stem completion task relative to the young adults, the magnitude of priming was equivalent for these two groups, and reliably greater than that of the dementia participants. These results suggest that not all aspects of memory function are impaired in MCI relative to healthy aging.