Older adults encode more,not less: evidence for age-related attentional broadening

Previous work has shown that older adults attend to and implicitly remember more distracting information than young adults; however, it is unknown whether they show a corresponding decrease in implicit memory for targets in the presence of distracters. Using implicit memory tests, we asked whether older adults show a tradeoff in memory between targets and distracters. Here, young and older adults performed a selective attention task in which they were instructed to attend to target pictures and ignore superimposed distracter words. We measured priming for distracter words using fragment completion and for target pictures using naming time. Older adults showed greater priming for distracting words compared to young adults, but equivalent priming for target pictures. These results suggest that older adults have a broader attentional scope than young adults, encompassing both relevant and irrelevant information.     

Aging affects word-stem completion and recognition but not category generation

In this study, we investigated the effect of aging on two implicit memory tasks, word-stem completion and category generation, and on explicit recognition. We compared the performance of young and older adults on these implicit memory tasks with those of explicit recognition. We expected better performance of young than older adults in the explicit memory task and similar priming in both implicit memory tasks. The results showed that young adults performed better than older adults in the recognition task. Moreover, both age groups showed priming in the implicit memory tasks, although priming was greater in young adults compared to older adults in the word-stem completion memory task, whereas both age groups showed similar levels of priming in the category generation task. The present results showed dissociations as a function of age not only between the explicit and the implicit tasks but also between the implicit tasks.     

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.     

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.     

保留的跨通道启动与老化：对于近期观点的总结

通道内重复启动的研究提示老年人内隐记忆未受损, 这不只体现在视觉通道上还包括其他感觉通道(例如触觉、听觉和嗅觉)。然而很少有研究考察启动任务是否具有通道特异性。在以年轻人为被试的研究中发现跨通道迁移(视觉到触觉和触觉到视觉)和通道内迁移(视觉到视觉, 触觉到触觉)具有相似性。一项最近的研究进一步探索老年人在跨通道启动任务上是否受损。结果显示视觉和触觉间的跨通道启动在年轻被试和老年被试上都是保留的且具有对称性。并且, 对于自然声响、图片的通道内和跨通道启动任务随着年老化发展仍旧保留。这些行为结果和其它最近神经科学结果显示跨通道启动发生于枕叶后纹状皮层区, 而这一区域在老年人中未损坏。这一领域未来的研究方向包括利用不同知觉通道间、利用熟悉的和新异的刺激并结合行为的和脑成像的方法, 通过设计完善的跨通道启动来研究正常老人与阿尔兹海默病人, 还包括将设计得完善的启动任务包括在用于改善老年人记忆功能的项目中。     

Effects of aging on priming and skill learning.

This study examined the effects of aging on 2 kinds of implicit memory; repetition priming and skill learning. In Experiment 1, older adults showed less improvement in the skill of reading inverted words than did young adults, but priming performance did not differ for the 2 age groups. Similarly, in Experiment 2, in a partial-word identification task, skill learning was observed only for young adults, whereas there was no age difference in priming. Experiments 1a and 2a, however, showed that when older adults were presented with more perceptual information than were young adults, the age deficit in skill learning was eliminated. These results indicate that skill learning is impaired under data-limited conditions, whereas priming is unaffected under these conditions. It is proposed that the age deficit in skill learning is related to a deficit in perceptual organization and reorganization.     

内隐重复效应影响外显工作记忆的年龄差异

采用延迟样本匹配任务并控制被试对部分项目的有意识学习经验, 当前研究考察了老年被试与青年被试在追逐靶、排除分心物的过程中, 重复启动效应如何受到项目外显学习经验的影响。老年被试和青年被试首先学习一些物体图片, 这些熟悉的图片与一些新图片作为之后工作记忆任务的靶或分心物。结果发现, 老年被试与青年被试在追逐靶和排除分心物的过程中均受到项目之前学习经验的影响。无论是老年被试还是青年被试, 对靶的反应时均快于对分心物的反应时, 对外显学习过的靶(即熟悉靶)的反应时快于对未学习过的靶(即新靶)的反应时, 而拒绝熟悉的分心物需要的时间长于拒绝新分心物的时间。其次, 老年被试与青年被试均表现出对靶的重复效应, 即当靶(无论是熟悉的还是新的)在任务中重复出现时, 对其的反应时加快; 然而, 对分心物的重复效应显著减小。随着项目多次重复, 重复效应整体上减小, 但该效应的变化受到项目属性(靶或分心物)以及项目之前学习经验的影响。重要的是, 当熟悉的分心物反复出现时, 老年被试不但没有出现重复效应, 反而在拒绝该熟悉分心物上表现出困难, 反应时显著延长, 而在青年被试上没有该表现。这些结果说明, 老年被试的工作记忆任务成绩容易受到内隐熟悉性的干扰, 重复出现的干扰项产生的熟悉性使得老年被试难以拒绝。     

Dissociations between procedural and episodic memory: effects of time and aging

The issue of multiple memory systems is explored. Young and older adults (mean ages = 20 and 71, respectively) named pictures and were tested immediately, 1, 7, or 21 days later. Episodic memory (recognition) for pictures was significantly lower in older relative to young adults and declined systematically across all retention intervals in both age groups. In contrast, procedural memory (repetition priming in picture naming) revealed no reliable age differences. In both age groups, priming declined within the first 24 hr, but unlike recognition, there was no further decrement from 1 to 21 days. There were also within-subject dissociations: The magnitude of priming was equivalent for remembered and forgotten items, and the relation between recognition and priming across intervals was nonmonotic, revealing a reversed association. The findings were interpreted within a multiple-memory-systems framework.     

The effects of divided attention on auditory priming

Traditional theorizing stresses the importance of attentional state during encoding for later memory, based primarily on research with explicit memory. Recent research has begun to investigate the role of attention in implicit memory but has focused almost exclusively on priming in the visual modality. The present experiments examined the effect of divided attention on auditory implicit memory, using auditory perceptual identification, word-stem completion and word-fragment completion. Participants heard study words under full attention conditions or while simultaneously carrying out a distractor task (the divided attention condition). In Experiment 1, a distractor task with low response frequency failed to disrupt later auditory priming (but diminished explicit memory as assessed with auditory recognition). In Experiment 2, a distractor task with greater response frequency disrupted priming on all three of the auditory priming tasks as well as the explicit test. These results imply that although auditory priming is less reliant on attention than explicit memory, it is still greatly affected by at least some divided-attention manipulations. These results are consistent with research using visual priming tasks and have relevance for hypotheses regarding attention and auditory priming.     

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.     

Dysnomia in Alzheimer's disease: an evaluation of neurobehavioral subtypes.

The relative influence of perceptual and semantic features on naming performance was investigated with reference to the neurobehavioral profiles displayed by patients with Alzheimer's disease (AD). Forty-one patients were classified as manifesting a verbal, visual, or global subtype based upon their pattern of neuropsychological functioning. Perceptual characteristics of to-be-named pictures were varied by manipulating the amount of line detail, whereas semantic qualities were varied by altering word frequency norms. All AD subtypes were less accurate than normal elderly controls in naming low frequency pictures. Patients and controls took longer to name low frequency and high complexity pictures, and this effect was comparable across the AD groups. Patients with predominantly visual deficits were significantly slower in naming than controls, and those with verbal impairments made a higher proportion of semantic naming errors when compared to patients displaying visual or severe global impairments. These results suggest that deficits in semantic processing contribute to naming dysfunction in AD, and they highlight the importance of examining dissociations among neurobehavioral subtypes.     

Age differences in implicit memory: conceptual, perceptual, or methodological?

The authors examined age differences in conceptual and perceptual implicit memory via word-fragment completion, word-stem completion, category exemplar generation, picture-fragment identification, and picture naming. Young, middle-aged, and older participants (N = 60) named pictures and words at study. Limited test exposure minimized explicit memory contamination, yielding no reliable age differences and equivalent cross-format effects. In contrast, explicit memory and neuropsychological measures produced significant age differences. In a follow-up experiment, 24 young adults were informed a priori about implicit testing. Their priming was equivalent to the main experiment, showing that test trial time restrictions limit explicit memory strategies. The authors concluded that most implicit memory processes remain stable across adulthood and suggest that explicit contamination be rigorously monitored in aging studies.     

Short- and long-term implicit memory in aging and Alzheimer's disease

Implicit memory processes were investigated via picture naming in healthy young and older adults and in persons with mild Alzheimer's disease (AD). Repetition priming in picture-naming was intact in all groups over the course of a short retention interval (seconds), and only the AD group revealed a deficit over a longer interval (72 hours). In addition, the AD group showed impaired procedural memory, with no benefit of practice on picture-naming. Impaired long-term priming was related to severity of AD. Both theoretical and methodological implications are discussed.     

A comparison of implicit memory tests in schizophrenic patients and normal controls

The objective of the current study was to compare the performance of schizophrenic patients and normal controls on implicit memory tests. Two neuropsychological tasks were administered to 29 patients and normal participant samples. The implicit tests were: Word fragment completion and Word production from semantic categories. The priming score was the variable of interest. Priming effects are obtained in normal subjects and schizophrenia patients, regardless of the implicit test used. However, a dissociation in priming between normal and patient groups was observed, depending on the test used. For word fragment test, priming was identical between the two groups. However, for word production, priming obtained in schizophrenics was lower than priming in normal controls. Results confirm a dissociation effect in implicit memory tests. These results could be explained in the context of the Roediger and Blaxton (1987) distinction between data-driven and conceptually-driven processing. This evidence suggests that a complete neuropsychological assessment of memory in schizophrenia should include different kinds of implicit memory tests (procedural, perceptual, and conceptual tasks).     

The effect of ageing on the recollection of emotional and neutral pictures

This study investigated age-related differences in recognition memory for emotional and neutral pictures. Younger and older participants were asked to rate pictures according to their emotional valence, arousal, and visual complexity. Two weeks later they had to recognise these pictures and the states of awareness associated with memory were assessed with the "remember/know/guess" paradigm. We found that, although the influence of emotion on recognition accuracy (as assessed by d') was similar in both age groups, the tendency for positive and negative pictures to create a rich recollective experience was weaker in older adults. In addition, "remember" responses were more often based on a recollection of emotional reactions in older than in younger participants. We suggest that the elderly tend to focus on their feelings when confronted with emotional pictures, which could have impaired their memory for the contextual information associated with these stimuli.     

The effect of ageing on the recollection of emotional and neutral pictures

This study investigated age-related differences in recognition memory for emotional and neutral pictures. Younger and older participants were asked to rate pictures according to their emotional valence, arousal, and visual complexity. Two weeks later they had to recognise these pictures and the states of awareness associated with memory were assessed with the “remember/know/guess” paradigm. We found that, although the influence of emotion on recognition accuracy (as assessed by d′) was similar in both age groups, the tendency for positive and negative pictures to create a rich recollective experience was weaker in older adults. In addition, “remember” responses were more often based on a recollection of emotional reactions in older than in younger participants. We suggest that the elderly tend to focus on their feelings when confronted with emotional pictures, which could have impaired their memory for the contextual information associated with these stimuli.     

Intact and long-lasting repetition priming in amnesia.

In 2 experiments, we evaluated the ability of amnesic patients to exhibit long-lasting perceptual priming after a single exposure to pictures. Ss named pictures as quickly as possible on a single occasion, and later named the same pictures mixed with new pictures. In Experiment 1, amnesic patients exhibited fully intact priming effects lasting at least 7 days. In Experiment 2, the priming effect for both groups was shown to depend on both highly specific visual information and on less visual, more conceptual information. In contrast, recognition memory was severely impaired in the patients, as assessed by both accuracy and response time. The results provide the first report of a long-lasting priming effect in amnesic patients, based on a single encounter, which occurs as strongly in the patients as in normal Ss. Together with other recent findings, the results suggest that long-lasting priming and recognition memory depend on separate brain systems.     

How scenes containing visual errors affect speech fluency in young and older adults

We compared young and older adults’ speech during an error detection task, with some pictures containing visual errors and anomalies and other pictures error-free. We analyzed three disfluency types: mid-phrase speech fillers (e.g., It’s a little, um, girl), repetitions (e.g., He’s trying to catch the- the birds), and repairs (e.g., She- you can see her legs). Older adults produced more mid-phrase fillers than young adults only when describing pictures containing errors. These often reflect word retrieval problems and represent clear disruptions to fluency, so this interaction indicates that the need to form and maintain representations of novel information can specifically compromise older adults’ speech fluency. Overall, older adults produced more repetitions and repairs than young adults, regardless of picture type, indicating general age-related increases in these disfluencies. The obtained patterns are discussed in the context of the Transmission Deficit Hypothesis and other approaches to age-related changes in speech fluency.     

The benefits and costs of repeated memory tests for young and older adults

Repeated and prolonged searches of memory can lead to an increase in how much is recalled, but they can also lead to memory errors. These 3 experiments addressed the costs and benefits of repeated and prolonged memory tests for both young and older adults. Participants saw and imagined pictures of objects, some of which were physically or conceptually similar, and then took a series of repeated or prolonged recall tests. Both young and older adults recalled more on later tests than on earlier ones, though the increase was less marked for older adults. In addition, despite recalling less than did young adults, older adults made more similarity-based source misattributions (i.e., claiming an imagined item was seen if it was physically or conceptually similar to a seen item). Similar patterns of fewer benefits and more costs for older adults were seen on both free and forced recall tests and on timed and self-paced tests. Findings are interpreted in terms of age-related differences in binding processes.