When false recognition is unopposed by true recognition: Gist-based memory distortion in Alzheimer's disease.

The authors examined false recognition of semantic associates in patients with probable Alzheimer's disease (AD), older adults, and young adults using a paradigm that provided rates of false recognition after single and multiple exposures to word lists. Using corrected false recognition scores to control for unrelated false alarms, the authors found that (a) the level of false recognition after a single list exposure was lower in AD patients than in controls; (b) across 5 trials, false recognition increased in AD patients, decreased in young adults, and showed a fluctuating pattern in older adults; and (c) all groups showed an increase in true recognition over the 5 trials. Analyses suggested that AD patients built up semantic gist across trials, whereas both control groups were able to use increased item-specific recollection and more conservative response criteria to suppress gist-based false alarms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When memory does not fail: Familiarity-based recognition in mild cognitive impairment and Alzheimer's disease.

Recognition can be guided by familiarity, a restricted form of retrieval devoid of contextual recall, or by recollection, which occurs when retrieval is sufficient to support the full experience of remembering an episode. Recollection and familiarity were disentangled by testing recognition memory using silhouette object drawings, high target-foil resemblance, and both yes-no and forced-choice procedures. Theoretically, forced-choice recognition could be mediated by familiarity alone. Alzheimer's disease and its preclinical stage, mild cognitive impairment (MCI), were associated with memory impairments that were greater on the yes-no test. Remarkably, forced-choice recognition was unequivocally normal in patients with MCI compared with age-matched controls. Neuropathology in hippocampus and entorhinal cortex, known to be present in MCI, presumably disrupted recollection while leaving familiarity-based recognition intact. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of semantic encoding on recognition memory in Alzheimer's disease

Within the framework of the distinction between episodic and semantic memory, it has been argued that these two memory systems are organised in a hierarchical way. The hierarchical hypothesis assumes that episodic memory is a specific subsystem of semantic memory and therefore implies that episodic memory cannot exist without semantic memory. If this hypothesis is correct, it should be expected that patients with impaired semantic memory also have impaired episodic memory. In the present study, two experiments investigated the influence of semantic encoding on recognition memory performance in a population of 20 patients with Alzheimer's disease and 18 normal controls. Both experiments assessed recognition memory for semantically-related items. In Experiment 2, but not in Experiment 1, subjects were explicitly instructed to make a semantic association between the items. Alzheimer's disease patients were impaired, compared to the normal controls, on the recognition memory performance of both experiments. The ability to make a semantic association between two items was significantly and positively correlated with the subjects' performance on the recognition tasks. A further analysis showed that patients who were impaired on the semantic association task did significantly worse on the recognition task of Experiment 2 than normal controls and patients who were unimpaired on the semantic association task. These findings are discussed in the context of memory deficits in Alzheimer's disease, and are interpreted as supporting the view that episodic memory for an item is affected by the level of semantic awareness of that same item.     

Greater relative impairment of object recognition than of visuospatial abilities in Alzheimer's disease.

Histological investigation in Alzheimer's disease (AD) has indicated that the concentration of neurofibrillary tangles in inferotemporal cortex (IT) is greater than that found in posterior parietal cortex (PPC). Researchers hypothesized that the relative degree of impairment of visual function subserved by each of these cortical areas should reflect the disproportionate distribution of neuropathological changes. Eleven AD patients and 16 elderly controls received 8 tests of visual function, 4 of which have been shown previously to be selectively affected by IT lesions and 4 that are selective for PPC lesions. AD patients were significantly impaired on all 8 tests, but multivariate analysis indicated a relatively greater impairment on tests of IT function. The greater impairment of visual function mediated by IT relative to function mediated by PPC is consistent with differential degradation of the respective cortical areas. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Headings as memory facilitators: The importance of prior knowledge.

94 college student subjects read a 4,840-word passage on organization in memory with headings either present or absent. Those subjects who were enrolled in a college course on human memory were defined as the high-preexisting-knowledge subjects, and those subjects who had never been enrolled in such a course were defined as the low-preexisting-knowledge subjects. An analysis of the scores on the multiple-choice retention test revealed that the only significant facilitative effect of the headings was in the answering of main-idea retention test questions by subjects with high-preexisting knowledge about the topic. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of semantic and perceptual encoding on recognition memory in Alzheimer's disease

Previous results from a population of patients with Alzheimer's disease (Dalla Barba and Goldblum, 1996) demonstrated that the ability of patients to make a semantic association between two items was significantly and positively correlated to their performance on a yes/no recognition task for the same items and that patients who were impaired on the semantic task did significantly worse on the recognition task than patients who were unimpaired on the semantic task. These findings gave support to a hierarchical model of organization of human memory in which episodic memory depends on the integrity of semantic memory. The present study further investigates the relationship between semantic memory deficits and episodic recognition memory in 15 patients with Alzheimer's disease and 15 controls, as a function of their semantic and perceptual encoding abilities and of their cognitive impairment in other domains. The results confirmed the previous findings and showed that, although patients heavily relied on perceptual analysis, this type of encoding did not enhance their recognition memory. Correlations analyses showed that some patients who were not impaired in the semantic association, but with particularly low scores on a verbal fluency task presented with a pattern, in recognition memory tasks, that suggests a possible early involvement of frontal lobes in this subgroup of patients.     

Implicit memory in Alzheimer's disease: A meta-analysis.

Meta-analysis was performed on 33 articles (36 experiments involving 564 Alzheimer's disease [AD] patients and 592 controls). Overall, AD patients were significantly impaired on implicit memory tests, r?=?.163 (a difference of .329 SDs from normal performance). They were impaired on nonverbal tests (e.g., fragmented pictures), word stem completion, classical conceptual tests (e.g, free association), and on word-based perceptual tests with long delays. However, they performed normally on word-based perceptual tests (e.g., perceptual identification of words) with short study test delays. They also performed normally on word stem completion if they were older than 75, possibly because their age-matched controls were also impaired. These results are neither qualified by study list length nor patient mental status. None of the theories in the field is compatible with the results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Overdependence on degraded gist memory in Alzheimer's disease.

Alzheimer's disease (AD) reduces associative effects on false recognition in the Deese-Roediger-McDermott task, either due to impaired memory for gist or impaired use of gist in memory decisions. Gist processes were manipulated by blocking or mixing studied words according to their associations and by varying the associative strength between studied and nonstudied words at test. Both associative blocking and associative strength had smaller effects on false recognition in AD patients than in control participants, consistent with gist memory impairments. However, unlike the case with control participants, blocking influenced true and false recognition equally in AD patients, demonstrating an overdependence on gist when making memory decisions. AD also impaired item-specific recollections, relative to control participants, as true recognition of studied words was reduced even when the two groups were equated on gist-based false recognition. We propose that the overdependence on degraded gist memory in AD is caused by even larger impairments in item-specific recollections. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sparing of semantic memory in Alzheimer's disease.

A number of investigators have suggested that unlike the normal elderly population, patients with Alzheimer's disease have a severe semantic-memory deficit. However, the semantic-memory tasks used in previous studies have been confounded by the heavy demands they placed on effortful processing. In the present study, 20 demented (mean age 71 yrs) and 20 normal (mean age 69.8 yrs) elderly Ss were given a battery of episodic-memory tasks and 3 tasks that examined how intact and accessible their semantic memory was under conditions that did not require effortful processing. Although the demented Ss were greatly inferior to the normal Ss on the episodic-memory tests, they performed equally well on the semantic-memory test: The naming latency of both groups was equally facilitated by a semantic prime, the recall accuracy of both normal and demented elderly for a string of letters was similarly affected by the degree to which the string approximated English orthography, and recall accuracy for a string of words was affected equally in the 2 groups by the degree to which the word string obeyed syntactic and semantic rules. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The importance of prior knowledge when comparing examples: Influences on conceptual and procedural knowledge of equation solving.

Comparing multiple examples typically supports learning and transfer in laboratory studies and is considered a key feature of high-quality mathematics instruction. This experimental study investigated the importance of prior knowledge in learning from comparison. Seventh- and 8th-grade students (N = 236) learned to solve equations by comparing different solution methods to the same problem, comparing different problem types solved with the same solution method, or studying the examples sequentially. Unlike in past studies, many students did not begin the study with equation-solving skills, and prior knowledge of algebraic methods was an important predictor of learning. Students who did not attempt algebraic methods at pretest benefited most from studying examples sequentially or comparing problem types, rather than from comparing solution methods. Students who attempted algebraic methods at pretest learned more from comparing solution methods. Students may need sufficient prior knowledge in a domain before they benefit from comparing alternative solution methods. These findings are in line with findings on the expertise-reversal effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of prior knowledge on good and poor readers' memory of text.

We investigated how prior knowledge influences the amount of short-term nonverbal and verbal memory and long-term retention in students of high and low ability in reading comprehension. Sixty-four junior high students were divided into four equal-sized groups on the basis of preassessed reading ability (high and low) and preassessed amount of existing prior knowledge about baseball (high and low). Each subject silently read an account of a half inning of a baseball game. After reading, each subject recalled the account nonverbally by moving figures and verbally by retelling the story. After an interpolated task, they summarized the game and sorted passage sentences for idea importance. There was a significant main effect for prior knowledge on all measures. No interactions between prior knowledge and ability were found. These results delineate the powerful effect of prior knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The impact of attitudes on memory: an affair to remember

Many theories of the effects of attitudes on memory for attitude-relevant information would predict that attitudinally congenial information should be more memorable than uncongenial information. Yet, this meta-analysis showed that this congeniality effect is inconsistent across the experiments in this research literature and small when these effects are aggregated. The tendency of the congeniality effect to decrease over the years spanned by this literature appeared to reflect the weaker methods used in the earlier studies. The effect was stronger in 2 kinds of earlier experiments that may be tinged with artifact: those in which the coding of recall measures was not known to be blind and those that used recognition measures that were not corrected for bias. Nonetheless, several additional characteristics of the studies moderated the congeniality effect and suggested that both attitude structure and motivation to process attitude-relevant information are relevant to understanding the conditions under which people have superior memory for attitudinally congenial or uncongenial information.     

The deterioration of semantic memory in Alzheimer's disease.

Semantic memory impairment is a common feature of dementia of the Alzheimer type (DAT). Recent research has shown that patients with DAT are more impaired (relative to non-demented controls) in generating exemplars from a particular semantic category (e.g., animals) than words beginning with a particular letter, exhibit an altered temporal dynamic during the production of category exemplars, are impaired on confrontation naming tasks and make predominantly superordinate or semantically related errors, consistently misidentify the same objects across a variety of semantic tasks, and have alterations in multidimensional scaling models of their semantic network that are indicative of a loss of concepts and associations. These results are consistent with the view that Alzheimer's disease results in a breakdown in the organization and structure of semantic knowledge as neurodegeneration spreads to the association cortices that presumably store semantic representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gist memory in Alzheimer's disease: Evidence from categorized pictures.

The authors investigated gist memory (the general meaning, idea, or gist conveyed by a collection of items) for categorized color photographs in patients with Alzheimer's disease (AD) using an experimental paradigm in which participants are instructed to respond "yes" when a test item fits with a previously studied category, regardless of whether the specific item was actually studied. Compared with controls, the patients endorsed fewer studied items and similar numbers of nonstudied lure items. After the authors corrected for the baseline false-alarm rate, the patients showed a lower level of endorsements for nonstudied lure items compared with that of controls, suggesting that their gist memory is impaired. Implications of these findings for understanding gist memory and response bias in patients with AD are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Young children's false-belief reasoning: Interpretation of messages is no easier than the classic task.

E. J. Robinson and P. Mitchell (see record 1992-34569-001) devised a message-desire discrepant task in which a speaker gives a message based on a false belief. A correct nonliteral interpretation of the message requires taking into account this false belief, which children were more likely to achieve in this task than in a classic prediction task. In 2 studies reported here, the comparison using more closely matched tasks was repeated. Study 3 followed the Robinson and Mitchell procedure precisely but failed to replicate the constrast reported previously. Although the message-desire discrepant task reveals early understanding that messages are the product of mental representations, it offers no advantage over the classic test in revealing false-belief reasoning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory for Star Trek : The role of prior knowledge in recognition revisited.

Prior studies have found robust knowledge effects on recall of text ideas but have seldom found comparable effects on recognition. This inconsistency was examined in light of recent research on the component processes that underlie recognition memory. Using the remember/know paradigm, the authors found that experts made more remember judgments than novices, but only in response to text ideas relevant to their domain of expertise. Using the process-dissociation procedure, the authors found knowledge effects on recollection estimates, but not on familiarity estimates. The authors contend that knowledge effects have been difficult to detect in recognition because knowledge primarily affects recollection, whereas familiarity gives rise to good performance even among novices. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cue depreciation: When word fragment completion is undermined by prior exposure to lesser fragments.

Studied impairment in ability to think of a previously studied item resulting from a change in extra-item context from study to test in 5 experiments, using a total of 156 Ss (primarily university students). The following results were obtained: a fragment (e.g, r-i--rop) of a just-studied word (raindrop) was shown to be less readily completed if it was presented bit by bit (r------p, r----r-p, r-i--r-p, r-i--rop) rather than all at once (Exps I, III, IV, and V). No such effect was found if the word had not been studied beforehand (Exps II–V). This pattern of results occurred even when fragments of studied and nonstudied words occurred in the same test and under conditions in which Ss could not tell whether a given fragment was of a studied or nonstudied word (Exps IV and V). In addition, for words that had been studied beforehand, the impairment was shown to increase systematically with the number of steps involved in the presentation of the word fragment (Exp III) and also to persist when the time allowed for completion of the final version of the fragment was increased from 4 sec to a full minute (Exp V). The target words are appended. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The disparate effects of Alzheimer's disease and Huntington's disease on semantic memory.

Alzheimer's disease (AD) and Huntington's disease (HD) impair performance on semantic memory tasks, but researchers disagree on whether AD and HD cause these impairments in the same manner. According to one view, AD disrupts the storage of semantic memories, whereas HD disrupts the retrieval of semantic memories. Dissenters argue that AD, like HD, disrupts retrieval. In this study, participants generated category exemplars (e.g., kinds of fruits) for 1 min, and response latencies were examined. Relative to healthy controls, the 12 AD patients produced a larger proportion of responses earlier in the recall period, consistent with the view that AD patients quickly exhaust their limited supply of items in storage. By contrast, the 12 HD patients produced a larger proportion of their responses late in the recall period, consistent with the view that HD slows retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of normal aging and Alzheimer's disease on emotional memory.

Recall is typically better for emotional than for neutral stimuli. This enhancement is believed to rely on limbic regions. Memory is also better for neutral stimuli embedded in an emotional context. The neural substrate supporting this effect has not been thoroughly investigated but may include frontal lobe, as well as limbic circuits. Alzheimer's disease (AD) results in atrophy of limbic structures, whereas normal aging relatively spares limbic regions but affects prefrontal areas. The authors hypothesized that AD would reduce all enhancement effects, whereas aging would disproportionately affect enhancement based on emotional context. The results confirmed the authors' hypotheses: Young and older adults, but not AD patients, showed better memory for emotional versus neutral pictures and words. Older adults and AD patients showed no benefit from emotional context, whereas young adults remembered more items embedded in an emotional versus neutral context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Event-related brain potential evidence of spared knowledge in Alzheimer's disease.

The authors recorded event-related brain potentials (ERPs) to picture primes and word targets (picture-name verification task) in patients with Alzheimer's disease (AD) and in elderly and young participants. N400 was more negative to words that did not match pictures than to words that did match pictures in all groups: In the young, this effect was significant at all scalp sites; in the elderly, it was only at central-parietal sites; and in AD patients, it was limited to right central-parietal sites. Among AD patients pretested with a confrontation-naming task to identify pictures they could not name, neither the N400 priming effect nor its scalp distribution was affected by ability to name pictures correctly. This ERP evidence of spared knowledge of these items was complemented by 80% performance accuracy. Thus, although the name of an item may be inaccessible in confrontation naming, N400 shows that knowledge is intact enough to prime cortical responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)