Tamiko Azuma

Episodic memory reflected in printed word naming

Although memory is typically measured by recall or recognition, it is also expressed by fluent or stylized task performance. In this experiment, 12 volunteers (calledspeakers) completed four experimental stages over a 2-week period. They read printed words aloud in two sessions, before and after exposure to auditory training tokens. They later completed a recognition memory test, discriminating old from new words. Groups ofperceptual judges assessed the speakers vocal imitation by comparing utterances recorded before and after training and deciding which sounded like “better imitations” of the training tokens. The data showed clear evidence of postexposure imitation, with systematic effects that preclude strategic explanations. The contents of episodic memory were reflected by participants speaking style while they were reading aloud. Together, the imitation and recognition data suggest that memory preserves detailed traces of spoken words; those traces were apparently activated when participants later read the same words in the same context.

Working Memory and Perseveration in Verbal Fluency.

Letter and semantic fluency tasks are often used in neuropsychological assessment and are sensitive to many conditions. Performance is assessed by correct responses and errors, including perseverations. Healthy young adults performed letter and semantic fluency tasks. One group performed these tasks in the conventional manner; 2 other groups performed them while maintaining memory loads. The memory loads consisted either of words from the same category as the fluency task or of words from a different category. The results showed little effect of memory loads on correct responses but significant effects of memory load on perseveration rates: Same-category loads resulted in higher rates, especially in letter fluency. The results are discussed in terms of frontal lobe function in verbal fluency.

Comparing the difficulty of letter, semantic, and name fluency tasks for normal elderly and patients with Parkinson's disease

Research on the effect of Parkinsons disease (PD) on verbal fluency has produced conflicting results. In this study, 88 PD patients with no dementia, 11 PD patients with questionable mental status, 15 PD patients with dementia, and 46 elders free from mental disorder were administered a variety of semantic, letter, and name fluency tasks. The results revealed that, contrary to popular assumption, semantic fluency was not always superior to letter fluency. Rather, verbal fluency was influenced by the nature of the individual categories. Interestingly, the relative difficulty of many categories was fairly stable across groups. The results also indicated that the individual fluency tasks were differentially sensitive to the mental status of the PD patients. Overall, the findings suggest that closer attention to the nature of the tested categories may help clarify the inconsistent effects of PD on verbal fluency.

Masked priming for prefixed words with bound stems : Does submit prime permit ?

Masked priming effects for prefixed words sharing a bound stem (e.g., submit-PERMIT) are compared with priming effects for semantically transparent prefixed words (e.g., fold-UNFOLD). In three experiments, priming effects were obtained for both types with no significant difference between them. These results suggest that semantic transparency is not critical for priming in this paradigm. However, in Experiment 2, priming in the bound stem condition did not differ significantly from an orthographic control condition (e.g., shallow-FOLLOW). In Experiment 3, form priming effects were suppressed by the use of close distractors and a longer prime duration. The morphological effects remained unaltered, indicating that they were not a product of orthographic overlap. The magnitude of bound stem priming was also found to be related to productivity of the stem.

“Blaming The Victim” Under Memory Load

When presented with negative outcomes, people often engage in counterfactual thinking, imagining various ways that events might have been different. This appears to be a spontaneous behavior, with considerable adaptive value. Nevertheless, counterfactual thinking may also engender systematic biases in various judgment tasks, such as allocating blame for a mishap, or deciding on the appropriate compensation to a victim. Thus, counterfactuals sometimes require thought suppression or discounting, potentially resource-demanding tasks. In this study, participants made mock-jury decisions about control and counterfactual versions of simple stories. The judgments of two groups of participants, differing in their respective levels of working memory capacity, were compared. In addition, all participants held memory loads during various stages of the primary task. Lower-span individuals were especially susceptible to bias associated with the counterfactual manipulation, but only when holding memory loads during judgment. The results suggest that counterfactual thoughts arise automatically, and may later require effortful, capacity-demanding suppression.

Cross-sectional analysis of Alzheimer disease effects on oral discourse in a picture description task

Summary:To examine the relation of dementia severity to the quality and quantity of oral discourse of individuals with Alzheimer disease (AD), a picture description task was administered to elicit oral discourse samples from 63 AD subjects, five individuals with very mild cognitive impairment, and 52 normal controls. Eight measures of discourse were used: total words, information units, conciseness, circumlocutions, frustrations, aborted phrases, revisions, and ideational repetitions. Information units, which decreased with increased dementia severity, proved to be the best measure for evaluating the effects of AD on oral descriptive discourse. The conciseness index also decreased with increased dementia severity, and a significantly greater proportion of AD discourse samples contained ideational repetitions. Circumlocutions and frustrations rarely occurred, and although the discourse of AD subjects was more likely to contain an aborted phrase, the frequency of aborted phrases did not vary by stage of dementia. Revisions were commonly observed in the discourse of both normal controls and AD subjects and did not differentiate the two groups

The effect of traumatic brain injury on sustained attention and working memory

Primary objective: The aim of the study was to evaluate working memory (WM) and sustained attention (SA) following severe traumatic brain injury (TBI). Research design: The study was a quasi-experimental design with two dependent measures. Methods and procedures: Nine individuals with severe TBI and nine non-injured controls completed two visual tasks containing alphabetic stimuli: a WM task (2-back task) and a 10-minute SA task. Main outcomes and results: Participants with TBI had lower hit rates and higher false alarm rates than controls on the WM task. Quantitative analysis of the group data did not reveal a differential deficit in SA; however, post-hoc qualitative visual analysis of individual data revealed considerable variability in four participants with TBI, indicating evidence of impaired SA in select individuals. The hit rates for both tasks were positively correlated, supporting the contention that WM and SA are inter-related. Conclusions: This study provides further evidence of WM deficits following TBI as well as possible SA deficits in some individuals. The results also suggest that WM and SA are inter-related processes. Future studies are needed to replicate the results with larger sample sizes. Based on these findings, patients with TBI may present with WM and SA deficits.

Sensitivity to expectancy violations in healthy aging and mild cognitive impairment.

In this study, individuals with mild cognitive impairment (MCI) were tested to see if executive dysfunction impacts their implementation of expectancy biases in a priming task. Young adults, healthy older adults, and individuals with MCI made speed-related decisions to sequentially presented word pairs. The proportion of category related (e.g., apple-fruit) versus coordinate related (apple-pear) pairs was varied to create different expectancy biases. When the proportion of category pairs was high (80%), the control groups showed an expectancy bias: Significant inhibition was observed for coordinate pairs compared with category pairs. The MCI group also demonstrated an expectancy bias but with much larger costs for unexpected targets. The findings suggest that individuals with MCI are inordinately sensitive to expectancy violations, and these findings are discussed in terms of possible executive dysfunction.

Gender differences in language of Alzheimer disease patients revisited.

Results of recent investigations suggest that Alzheimer disease (AD) has a more deleterious effect on language in women than in men. This intriguing finding motivated an analysis of the language performance of probable AD patients, equally divided as to gender, on a variety of language comprehension and production tests. Cross-sectional data were available for 63 probable AD subjects and longitudinal data were available for 26. In addition to analysis of covariance used with the cross-sectional data, effect sizes were calculated. The longitudinal data were analyzed with repeated-measures analyses of covariance. The sum of scores on the orientation items of the Mini-Mental State Examination was used as the covariate in both analyses. No significant differences between the performance scores of male and female subjects were obtained for either the cross-sectional or longitudinal data. All effect sizes of gender were relatively small, with female patients outperforming males on most language tests. Results are discussed in the context of previous findings and comparison of the effect sizes among studies.

Working memory capacity: Is there a bilingual advantage?

Previous studies suggest that bilinguals have certain executive function advantages over monolinguals. However, few studies have examined specific working memory (WM) differences between monolinguals and bilinguals using complex span tasks. In the current study, 52 bilingual and 53 monolingual speakers were administered simple and complex WM span tasks, including a backward digit-span task, standard operation span tasks and a non-verbal symmetry span task. WM performance was a strong predictor of performance on other WM tasks, whereas bilingual status was not. Thus, the present study did not find evidence of a bilingual advantage in WM capacity.