Sex differences in spatial task performance of patients with and without unilateral cerebral lesions

Two visuospatial tasks, the WAIS Block Design and the Street Gestalt Completion Test, were administered to men and women with and without unilateral cerebral lesions. These two tasks represent different categories of visuospatial functions. The Street test is a visual-perceptual gestalt task, requiring the closure of fragmented pictures, whereas Block Design is an analytical, manipulospatial task requiring rotation of spatial coordinates. For the non-brain-damaged group, the men showed a nonsignificant trend toward better Block Design performance relative to the women, whereas there was no sex-related difference in Street performance. For the brain-damaged groups, patients with right hemisphere lesions performed significantly worse than patients with left hemisphere lesions on both the Street test and Block Design, indicating that both tasks were more sensitive to right hemisphere functioning. There was, however, a significant sex X side of lesion interaction on Block Design only, with the men showing a more asymmetrical pattern of scores. These results suggest that sex differences in functional lateralization may underlie sex differences in visuospatial ability, and that sex differences in functional lateralization may be present for only certain visuospatial processes.     

Explicit and implicit memory in dementia and normal ageing

Summary In two experiments, young subjects, healthy elderly subjects (spouses), and highly intelligent elderly subjects (elite elderly), were compared with dementia patients in a variety of explicit and implicit memory tasks, to investigate two issues: whether priming in Alzheimer-type dementia is contingent upon the presence of pre-existing representations, and whether intelligence modulates performance in explicit memory tasks in healthy ageing. Dementia patients performed as well as spouses in a homophone-spelling task. Moreover, they established new contextual associations when memory was tested by word-stem completion. The hypothesis that priming in dementia is contingent upon pre-existing memory representations was not supported. Spouses, elite elderly, and young subjects did not differ in their ability to recognize correctly recently heard stimuli or to complete word stems. However, recall of lists of words and paired associates was better in both young and elite elderly subjects than in spouses. It is concluded that intellectual capacity rather than chronological age in healthy subjects modulates performance in explicit-memory tasks.Now at The Social Psychiatry Unit, Australian National University, Canberra, ACT, Australia     

Influences of item organizability and semantic retrieval cues on word recall in very old age

Abstract

This research investigated the influence of organizational structure in the materials and category cues at retrieval on episodic memory performance in very old age. A community-based sample of healthy, very old adults (N = 224) between 75 and 96 years was presented with two lists of words: a list of semantically unrelated words and a list of words from four taxonomic categories randomly intermixed. Free recall was assessed for both tasks and, for the organizable list, subjects received a cued recall test as well. Results showed an overall age-related deterioration of memory performance, although the ability to utilize item organizability and retrieval cues remained intact across age. Evidence from data on memory performance, as well as analyses of the nature of organizable free recall, suggests that problems at both encoding and retrieval may underlie the age-related performance deficit. In addition, there were age-related increases in (a) forgetting between free and cued recall, and (b) intrusion errors. Finally, regression analyses indicated that, in addition to age, level of schooling as well as markers of general cognitive status (the Mini-Mental State Examination) and fluid intelligence (Block Design) accounted for performance variation across all memory tasks.     

Cultural differences in visual attention: Implications for distraction processing

We investigated differences between participants of East Asian and Western descent in attention to and implicit memory for irrelevant words which participants were instructed to ignore while completing a target task (a Stroop Task in Experiment 1 and a 1‐back task on pictures in Experiment 2 ). Implicit memory was measured using two conceptual priming tasks (category generation in Experiment 1 and general knowledge in Experiment 2 ). Participants of East Asian descent showed reliable implicit memory for previous distractors relative to those of Western descent with no evidence of differences on target task performance. We also found differences in a Corsi Block spatial memory task in both studies, with superior performance by the East Asian group. Our findings suggest that cultural differences in attention extend to task‐irrelevant background information, and demonstrate for the first time that such information can boost performance when it becomes relevant on a subsequent task.     

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.     

Dementia and working memory

This study explored the hypothesis that patients suffering from dementia of the Alzheimer type (DAT) are particularly impaired in the functioning of the Central Executive component of working memory, and that this will be reflected in the capacity of patients to perform simultaneously two concurrent tasks. DAT patients, age-matched controls and young controls were required to combine performance on a tracking task with each of three concurrent tasks, articulatory suppression, simple reaction time to a tone and auditory digit span. The difficulty of the tracking task and length of digit sequence were both adjusted so as to equate performance across the three groups when the tasks were performed alone. When digit span or concurrent RT were combined with tracking, the deterioration in performance shown by the DAT patients was particularly marked.     

Phonological memory in bilinguals and monolinguals

In the present study, we examined the effects of lexical-semantic knowledge and of difficulty level on phonological memory performance by monolingual adult English speakers and bilingual adult Korean?CEnglish speakers. The monolingual English speakers were more proficient in English than the bilingual speakers. All participants were tested on a range of phonological memory tasks in English. We manipulated the degree to which the phonological memory tasks involved lexical-semantic knowledge of English (word-span task, digit-span task, and nonword repetition task), as well as the difficulty level of the tasks. Results revealed that on the word-span task (highest level of lexical-semantic knowledge), monolinguals outperformed bilinguals at the easier levels of the task but bilinguals outperformed monolinguals at the more difficult levels of the task. For the digit-span and nonword repetition tasks, monolinguals outperformed bilinguals at the easier levels of the tasks, but the differences between the two groups vanished with the increase in the difficulty levels. Together, these results suggest that proficiency-based differences between monolingual and bilingual phonological memory performance depend on the degree to which the tasks rely on lexical-semantic knowledge and the difficulty level of the task.     

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.     

Visuo-spatial and verbal working memory in the five-disc Tower of London task: An individual differences approach

This paper reports a study of the roles of visuo-spatial and verbal working memory capacities in solving a planning task—the five-disc Tower of London (TOL) task. An individual differences approach was taken. Sixty adult participants were tested on 20 TOL tasks of varying difficulty. Total moves over the 20 TOL tasks was taken as a measure of performance. Participants were also assessed on measures of fluid intelligence (Raven's matrices), verbal short-term storage (Digit span), verbal working memory span (Silly Sentence span), visuo-spatial short-term storage (Visual Pattern span and Corsi Block span), visuo-spatial working memory (Corsi Distance Estimation), visuo-spatial processing speed (Manikin test), and verbal speed (Rehearsal speed). Exploratory factor analysis using an oblique rotation method revealed three factors which were interpreted as (1) a visuo-spatial working memory factor, (2) an age-speed factor, and (3) a verbal working memory factor. The visuo-spatial and verbal factors were only moderately correlated. Performance on the TOL task loaded on the visuo-spatial factor but did not load on the other factors. It is concluded that the predominant goal-selection strategy adopted in solving the TOL relies on visuo-spatial working memory capacity and particularly involves the active “inner scribe” spatial rehearsal mechanism. These correlational analyses confirm and extend results previously obtained by use of dual task methods, (Phillips, Wynn, Gilhooly, Della Sala, & Logie, 1999).     

任务重要性对前瞻记忆的迁移恰当加工效应的影响

为考察任务重要性对前瞻记忆迁移恰当加工（Transfer-appropriate Processing,以下简称TAP）效应的影响,随机选取在校大学生48名,采用基于双重任务的实验研究范式,探究了任务重要性对前瞻记忆TAP效应的影响。研究结果表明：任务的重要性对前瞻记忆TAP效应有显著的影响。当进行中任务较重要时,TAP效应存在;而当前瞻记忆任务较重要时,TAP效应没有出现     

Individual differences in sentence memory

Results from an experiment with two parts are presented in this paper. In part one, participants listened to sentences containing two, three, four, or five clauses, and were asked questions about the content of the sentences. The results of part one demonstrate that an important unit of representation in sentence memory is the clause, and not some other component of discourse structure. In part two, the same group of participants performed eight different short-term storage/working memory tasks. A composite complex span score was computed for each participant based on three working memory tasks closely based on Daneman & Carpenter's (1980) reading span task. This working memory measure was significantly correlated with the participants' performance on the sentence memory task in part one. A second working memory measure—N-back—was also significantly correlated with the participants' performance on the sentence memory task, and there was no correlation between their performance on the complex span task and the N-back task. It is therefore concluded that (i) working memory consists of a number of dissociable components; and (ii) memory for sentences taps into more than one of these working memory components. Furthermore, the high correlations of sentence memory with the complex span and the N-back tasks (neither of which are language processing tasks) suggests that memory for sentences is not simply a result of linguistic experience; rather, it is likely that an independent working memory component contributes to participants' performance on the sentence memory task.     

Acute alcohol effects on repetition priming and word recognition memory with equivalent memory cues

Acute alcohol intoxication effects on memory were examined using a recollection-based word recognition memory task and a repetition priming task of memory for the same information without explicit reference to the study context. Memory cues were equivalent across tasks; encoding was manipulated by varying the frequency of occurrence (FOC) of words in the study lists. Twenty-two female and male social drinkers (age 21-24 years) completed equivalent versions of the memory tasks in two counterbalanced sessions (alcohol challenge, no-alcohol). Alcohol and the FOC manipulation affected recollection-based memory processing, but not repetition priming. Results supported alcohol's dissociative effects on memory systems.     

Selective interference with image retention and generation: Evidence for the workspace model

We address three types of model of the relationship between working memory (WM) and long-term memory (LTM): (a) the gateway model, in which WM acts as a gateway between perceptual input and LTM; (b) the unitary model, in which WM is seen as the currently activated areas of LTM; and (c) the workspace model, in which perceptual input activates LTM, and WM acts as a separate workspace for processing and temporary retention of these activated traces. Predictions of these models were tested, focusing on visuospatial working memory and using dual-task methodology to combine two main tasks (visual short-term retention and image generation) with two interference tasks (irrelevant pictures and spatial tapping). The pictures selectively disrupted performance on the generation task, whereas the tapping selectively interfered with the retention task. Results are consistent with the predictions of the workspace model.     

Prospective and retrospective memory in normal aging and dementia: an experimental study

Two experiments investigated the effects of normal aging and dementia on laboratory-based prospective memory (PM) tasks. Participants viewed a film for a later recognition memory task. In Experiment 1, they were also required either to say "animal" when an animal appeared in the film (event-based PM task) or to stop a clock every 3 min (time-based PM task). In both tasks, young participants were more successful than older participants, who were, in turn, more successful than patients with Alzheimer's disease (AD). For successful remembering in the time-based task, older participants and AD patients checked the clock more often than did young participants. In Experiment 2, participants were asked to reset a clock either when an animal appeared in the film (unrelated cue-action) or when a clock appeared in the film (related cue-action). Responses were faster in the related condition than in the unrelated condition. Again, there were differences in PM performance between young and older participants, and between older participants and AD patients. The observed deficits were not due to the forgetting of the PM task instructions in either experiment. Retrospective memory (RM) tasks (digit span, sentence span, free recall, and recognition) were more impaired by AD than were the PM tasks. Factor analysis revealed separate factors corresponding to RM and PM.     

Varying the importance of a prospective memory task: differential effects across time- and event-based prospective memory

Only few studies have addressed the issue of task importance in prospective memory. Most of them, but not all, have shown that perceived task importance does improve prospective memory performance. However, there is little understanding of (1) the conditions under which importance of the prospective memory task makes a difference in performance and (2) the mechanisms by which perceived task importance has an effect on prospective memory performance. The present study reports two experiments that manipulate task importance in a time-based and an event-based prospective memory paradigm. Results show that importance has an effect on the time-based but not on the event-based task. Further analyses of the performance in the cover tasks as well as the monitoring behaviour indicate that importance improves prospective memory to the degree the task requires the strategic allocation of attentional resources.     

Interference with visual short-term memory

Working memory (Baddeley and Hitch 1974) incorporates the notion of a visuo-spatial sketch pad; a mechanism thought to be specialized for short-term storage of visuo-spatial material. However, the nature and characteristics of this hypothesized mechanism are as yet unclear. Two experiments are reported which examined selective interference in short-term visual memory. Experiment 1 contrasted recognition memory span for visual matrix patterns with that for visually presented letter sequences. These two span tasks were combined with concurrent arithmetic or a concurrent task which involved manipulation of visuo-spatial material. Results suggested that although there was a small, significant disruption by concurrent arithmetic of span for the matrix patterns, there was a substantially larger disruption of the letter span task. The converse was true for the secondary visuo-spatial task. Experiment 2 combined the span tasks with two established tasks developed by Brooks (1967). Span for matrix patterns was disrupted by a visuo-spatial task but not by a secondary verbal task. The converse was true for letter span. These results suggest that the impairment in short-term visual memory resulting from secondary arithmetic reflects a small general processing load, but that the selective interference due to mode of processing is by far the stronger effect. Results are interpreted as being entirely consistent with the notion of a specialized visuo-spatial mechanism in working memory.     

Defects of immediate memory related to the cerebral blood flow distribution

Different forms of memory defects were studied in 16 patients with organic dementia. The test performance was related to the regional cerebral blood flow (rCBF) in the left (dominant) hemisphere. Verbal memory (Paired Associates) correlated to the blood flow in temporal and parietal regions. Spatial recognition (Memory for Objects, Memory for Geometrical Design) correlated to the temporal and lower frontal regions. One spatial memory test (Visual Retention test) correlated to the temporal region only. Another spatial memory test (Memory for Design) did not show correlations to any regions of the dominant hemisphere. Finally it was found that the hemisphere mean flow values did not correlate to performance. This emphasizes the main finding—the regional correlations. It is concluded that memory performance involves various extratemporal regions depending upon the specific quality of the memory task to be performed.     

A study of alpha hemispheric asymmetries for verbal and nonverbal stimuli in males and females

The alpha hemispheric asymmetries of males and females were examined with electroencephalographic (EEG) techniques during exposure to connected speech and nonlinguistic stimuli. The subject selection controlled for familial handedness and each subject was administered the Block Design and Vocabulary Subtests of the WAIS as a general measure of “visual-spatial” and “verbal” ability. The results showed that there was less alpha in the right hemisphere for nonverbal tasks and less alpha in the left hemisphere for verbal tasks. The females showed significantly more “lateralization” during the tasks as compared to the males. The results are discussed in terms of processing differences and the possible effects of subject variables, stimulus mode, stimulus presentation, and task requirements on neurolinguistic research results.     

Concurrent performance of two memory tasks: evidence for domain-specific working memory systems

Previous studies of dual-task coordination in working memory have shown a lack of dual-task interference when a verbal memory task is combined with concurrent perceptuomotor tracking. Two experiments are reported in which participants were required to perform pairwise combinations of (1) a verbal memory task, a visual memory task, and perceptuomotor tracking (Experiment 1), and (2) pairwise combinations of the two memory tasks and articulatory suppression (Experiment 2). Tracking resulted in no disruption of the verbal memory preload over and above the impact of a delay in recall and showed only minimal disruption of the retention of the visual memory load. Performing an ongoing verbal memory task had virtually no impact on retention of a visual memory preload or vice versa, indicating that performing two demanding memory tasks results in little mutual interference. Experiment 2 also showed minimal disruption when the two memory tasks were combined, although verbal memory (but not visual memory) was clearly disrupted by articulatory suppression interpolated between presentation and recall. These data suggest that a multiple-component working memory model provides a better account for performance in concurrent immediate memory tasks than do theories that assume a single processing and storage system or a limited-capacity attentional system coupled with activated memory traces.     

Perceptual implicit memory requires attentional encoding

Perceptual implicit memory for previously attended and unattended words was measured either in a word-stem completion task or in a perceptual fluency (perceptual identification) task. Subjects (N = 144) first engaged in a focused attention task in which they were to identify one of two words presented for 100, 200, or 300 msec. Words were classified as attended if they were reported during the focused attention task and unattended if they were not. Results for both implicit memory tests indicated reliable perceptual implicit memory for attended words but not for unattended words, regardless of focused attention exposure duration. The results indicate that perceptual implicit memory tasks reflect attentional encoding processes; that is, words must undergo attentional encoding if they are to affect performance on a later perceptual implicit memory test.