The role of forgetting rate in producing a benefit of expanded over equal spaced retrieval in young and older adults.

The current study examined the effects of two manipulations on equal and expanded spaced retrieval schedules in young and older adults. First, we examined the role that the type of expansion (systematic vs. nonsystematic) has in producing a benefit of expanded retrieval. Second, we examined the influence of an immediate retrieval attempt to minimize forgetting after the original encoding event. It was predicted that including multiple retrieval attempts with minimal intervening spacing (best accomplished in a nonsystematic retrieval schedule) would be necessary to produce a benefit of expanded retrieval over equal spaced retrieval for older adults but not young adults due to age differences in working memory capacity. Results from two experiments revealed that the presence of an expanded over equal spaced retrieval benefit is modulated by the extent to which the spacing conditions minimize forgetting in the early retrieval attempts in the spaced conditions. As predicted, these conditions differ substantially across young and older adults. In particular, in older adults two intervening items between early retrieval attempts produce dramatic rates of forgetting compared to one intervening item, whereas younger adults can maintain performance up to five intervening events in comparable conditions. Discussion focuses on age differences in short term forgetting, working memory capacity, and the relation between forgetting rates and spaced retrieval schedules. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The influence of nanoadditives on surface, permeability and mechanical properties of self-organized organic–inorganic nanocomposite coatings

Transparent and colorless nanocomposite coatings were prepared from a hybrid organic–inorganic matrix and several inorganic nanofillers. The products are characterized by a high degree of self-assembling of the matrix which was prepared from an epoxy-functional organosilicon precursor and an oligomeric diamine. Unmodified and chemically modified montmorillonite, bentonite, laponite, and colloidal silica were used as nanofillers, differing in shape, size, and origin. The nanoadditive concentration in coatings was always 0.5 wt%. Solid-state NMR (¹³C and ²⁹Si CP/MAS) spectroscopy was used for estimation of polyaddition and polycondensation degree in the polymer matrix in order to evaluate its structure changes caused by interaction with the nanoadditives. The influence of the kind of additive on the dynamic mechanical properties, gas permeability, and surface properties (topography, roughness) is discussed.     

Prospective memory and apolipoprotein e in healthy aging and early stage Alzheimer's disease.

The present study examined whether prospective memory performance discriminates healthy aging from very mild dementia of the Alzheimer type (DAT) and individuals at risk for DAT because of the presence of the apolipoprotein E (ApoE) ε4 allele. Four groups (young subjects, young-old control subjects, old-old control subjects, and subjects with very mild DAT) engaged in an event-based prospective memory task wherein they responded to a specific word embedded in a general knowledge test. Results indicated that prospective memory performance was clearly impaired in the very mild DAT group relative to the healthy older control groups. Moreover, prospective memory performance appears to capture unique variance in discriminating these 2 groups above and beyond standard retrospective memory tests. However, prospective memory was not affected by ApoE status in the young-old control group and, contrary to predictions, the ε4+ old-old control subjects showed better performance than did the ε4- subjects. In contrast to the healthy individuals, in the very mild DAT group, ε4+ subjects showed deficits in performance relative to the ε4- subjects. Discussion focuses on prospective memory as a cognitive indicator of early stage DAT. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Encoding and retrieval differences between young and old: The impact of attentional capacity usage.

An experiment was conducted to investigate (a) whether the semantic processing deficit in the aged can be attributed to age differences in capacity usage during encoding and (b) age differences in terms of the interaction between encoding and retrieval operations. Young and older adults engaged in both a primary (semantic, rhyme, and arithmetic questions) and secondary task (probe monitoring) at encoding and retrieval. The study provided no evidence for the hypothesis that the age-related semantic processing deficit is the result of age differences in capacity usage during semantic and nonsemantic encoding. However, there was evidence that reinstating the encoded semantic context with the same semantic cue at retrieval did not help older subjects as much as younger subjects at recall. These results were interpreted as suggesting that there may be an age deficit in the effective use of semantic contextual information at encoding and retrieval rather than a simple age deficit in semantic processing at encoding. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Voice-specific information and the 20-second delayed-suffix effect.

Conducted 2 experiments with a total of 201 university students to investigate the nature of the delayed-suffix effect reported by M. J. Watkins and A. K. Todres (see record 1981-09636-001). In both experiments, Ss were presented lists of digits for serial recall. At the end of each list, either a tone or a voice reading aloud the word go was presented. The voice was either in the same voice that read the digits or in a different voice. Past research has indicated that the tone control produces the least interference, followed by the different-voice suffix, which in turn produces less interference than the same-voice suffix. The results of the present experiments indicate that when Ss were tested on immediate recall for the lists, the typical ordering of tone control, different-voice suffix, and same-voice suffix on recall at the last serial position was found. However, when there was a 20-sec filled interval between the last list item and the suffix, there was only a difference between the tone control and the same- and different-voice suffixes with no difference between the latter 2 conditions. In addition, Exp II failed to support a simple attentional account of the differential influence of voice in the immediate and delayed-recall conditions. It is concluded that the results support a perceptual tuning mechanism in which perceptual specificity decreases with the passage of time. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention and driving performance in Alzheimer's disease

The present study examined the relationship between visual attention measures and driving performance in healthy older adults and individuals with very mild and mild dementia of the Alzheimer type (DAT). Subjects were administered an on-road driving assessment and three visual attention tasks (visual search, visual monitoring, and useful field of view). The results indicated that error rate and reaction time during visual search were the best predictors of driving performance. Furthermore, visual search performance was predictive of driving performance above and beyond simple dementia severity and several traditional psychometric tests. The results suggest that general cognitive status may be useful for identifying individuals "at risk" for unsafe driving. However, measures of selective attention may serve to better differentiate safe versus unsafe drivers, especially in the DAT population.     

Predicting conversion to dementia of the Alzheimer’s type in a healthy control sample: The power of errors in stroop color naming.

In the present study, we investigated which cognitive functions in older adults at Time A are predictive of conversion to dementia of the Alzheimer’s type (DAT) at Time B. Forty-seven healthy individuals were initially tested in 1992–1994 on a trial-by-trial computerized Stroop task along with a battery of psychometric measures that tap general knowledge, declarative memory, visual–spatial processing, and processing speed. Twelve of these individuals subsequently developed DAT. The errors on the color incongruent trials (along with the difference between congruent and incongruent trials) and changes in the reaction time distributions were the strongest predictors of conversion to DAT, consistent with recent arguments regarding the sensitivity of these measures. Notably in the psychometric measures, there was little evidence of a difference in declarative memory between converters and nonconverters, but there was some evidence of changes in visual-spatial processing. Discussion focuses on the accumulating evidence suggesting a role of attentional control mechanisms as an early marker for the transition from healthy cognitive aging to DAT. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Does expanded retrieval produce benefits over equal-interval spacing? Explorations of spacing effects in healthy aging and early stage Alzheimer's disease.

Three experiments explored different schedules of retrieval practice in young adults, older adults, and individuals with dementia of the Alzheimer type. In each experiment, an initial acquisition phase was presented in which participants studied or attempted to retrieve response words to cues, followed by a later cued-recall test. Experiment 1 produced a benefit of expanded retrieval over equal-interval retrieval during acquisition, but this benefit was lost in final cued recall. In Experiments 2 and 3, participants received corrective feedback during acquisition and modified spacing schedules. There was again no evidence of a difference between expanded and equal-interval conditions in final cued recall. Discussion focuses on the potential benefits and costs of expanded retrieval on a theoretical and applied level. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related differences in the impact of spacing, lag, and retention interval.

An experiment is reported that examines age-related differences in the lag effect and its relation to retention interval. A total of 30 young and 30 older adults received both once-presented pairs and twice-presented pairs that were tested in a continuous cued-recall paradigm either after a short retention interval (2 pairs intervening between the last presentation of a pair and its test) or a long retention interval (20 pairs intervening between the last presentation of a pair and its test). In addition, the twice-presented pairs were separated by either 0, 1, 4, 8, or 20 intervening pairs. The results replicated the interaction between retention interval and lag that has been reported by Glenberg (1976, Journal of Verbal Learning and Verbal Behavior, 15, 1–26). Furthermore, although the older adults performed considerably lower than the younger adults in overall recall performance, their data were remarkably similar to the younger adults in the patterning of means. A mathematical modeling procedure was used to fit the data to Estes' stimulus fluctuation model. The results of this modeling procedure suggest that, compared with younger adults, older adults (a) encode less contextual information at a given point in time and (b) have a slower rate of contextual fluctuation across time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)