Chiari 1000 Registry Project: assessment of surgical outcome on self-focused attention, pain, and delayed recall.

BACKGROUND: Prior research has typically found a negative relationship between chronic pain and memory, and we examined whether cognitive control processes (e.g. reflection and rumination) moderated this relationship in individuals with Chiari malformation Type I (CM). CM is a neurological condition in which the cerebellar tonsils descend into the medullary and upper cervical spine regions potentially resulting in severe headaches and neck pain. METHODS: CM patients who had (n = 341) and had not (n = 297) undergone decompression surgery completed the McGill Pain Questionnaire-Short Form-Revised (SF-MPQ-2), the Rey Auditory Verbal Learning Test (RAVLT), and the Rumination-Reflection Questionnaire (RRQ). Immediate recall scores were compared to those of 102 healthy controls, and delayed recall performance was compared across other variables within the CM group. RESULTS: CM patients performed more poorly on immediate recall than did controls. Within CM patients, we observed main effects for reflection and age, and a pain x reflection x surgical status (surgery v. no surgery) interaction in which non-decompressed individuals with low levels of pain and high levels of reflection showed superior delayed recall relative to non-decompressed individuals with higher pain and all decompressed individuals. CONCLUSIONS: CM patients show an immediate recall deficit relative to controls, regardless of surgical status. High levels of reflection were associated with better delayed recall performance in non-decompressed CM patients with lower pain levels. High levels of chronic pain may overwhelm increased focused attention abilities, but higher levels of reflection partially overcome the distracting effects of pain and this may represent a type of resilience.

Visual attention and aging.

The present review of visual attentional processes and aging focuses on definitions of attention that emphasize some aspect of the control of information processing (selective attention) or the processing resources needed to drive these control processes (attentional capacity). Emphasis is placed on how increased adult age affects attentional mechanisms and how these age differences in attention affect overall information processing. Past research has emphasized that selective attention appears to be resistant to age-related decline. Age-related deficits in attentional capacity or processing resources, however, have been found. A review of more recent psychological research demonstrates the extension of the investigation of attention with emphasis on further defining what is selected in selective attention, and on reexamining the processing resources or capacity issue. Finally, developments in cognitive neuroscience are reviewed in terms of their relevance to attention and aging.

Evidence for a parallel input serial analysis model of word processing.

A parallel input serial analysis (PISA) model of word processing was developed and tested. The goal was to expand on the "critical processing duration" hypothesis of Johnson, Allen, and Strand (1989) so that both single-word and multiple-word presentation, letter detection data could be explained. In Experiments 1-3 four different word frequency categories on a single-presentation, letter detection task were used. These three experiments indicated that there was a curvilinear relationship between word frequency and letter detection reaction time (RT). That is, letter detection RTs for medium-high-frequency words were significantly longer than letter detection RTs for very-high-, low-, and very-low-frequency words. These results support the PISA model rather than the Healy, Oliver, and McNamara (1987) version of the unitization model. In Experiments 4-5 multiple-presentation (i.e., two words), letter detection tasks were used. The PISA model could also account for the results from these two experiments, but the unitization model could not.

Influence of case type, word frequency, and exposure duration on visual word recognition.

The authors report 4 lexical decision experiments in which case type, word frequency, and exposure duration were varied. These data indicated that there is a larger mixed-case disadvantage for nonwords than for words for longer duration presentations of targets. However, when targets were presented for 100 ms (followed by a postdisplay pattern mask), a larger mixed-case disadvantage occurred for words than for nonwords. For word frequency, the data from Experiments 1, 2, and 3 revealed a slightly larger mixed- case disadvantage for higher frequency words than for lower frequency words. (There was additivity between word frequency and case type for experiment 4.) These results are consistent with a holistically biased, hybrid model of visual word recognition but inconsistent with analytically biased, hybrid models of word recognition, such as the process model (Besner & Johnston, 1989) and the interactive-activation model (McClelland & Rumelhart, 1981).

Word frequency effects at brief exposure durations: comment on Paap and Johansen (1994).

K. R. Paap and L. S. Johansen (1994) proposed that word frequency effects do not occur on a lexical decision task (LDT) when postmasked target exposure duration is sufficiently brief because such a task prevents verification--their hypothesized locus of the word frequency effect. In making this assertion, they proposed that the activation interpretation of A. R. Dobbs, A. Friedman, and J. Lloyd (1985) and of P. A. Allen, M. McNeal, and D. Kvak (1992) was flawed. However, evidence that Paap and Johansen's conclusions were wrong and that their experimental design contained flaws is provided here. In Experiment 1 of the present study, word frequency effects were evident on an LDT at the 75% accuracy level proposed by Paap and Johansen as being sufficiently low to prevent verification. In Experiment 2 the mental lexica of participants from the same population as that used for Experiment 1 contained very-low-frequency words. Thus, the present results are consistent with an activation locus.

Age-related slowing and the time course of semantic priming in visual word identification.

In 4 experiments, the authors investigated the time course of semantic priming effects during 2 forms of visual word identification, lexical decision and pronunciation. On each trial, a target letter string was preceded by a single-word priming context. The effects of varying the stimulus onset asynchrony between the prime and the target indicated that the time course of semantic priming was equivalent for young and older adults. There were no consistent differences between lexical decision and pronunciation in the time course of semantic priming. The age differences associated with response selection were greater than would be predicted by generalized age-related slowing. The semantic priming effects were also inconsistent with a generalized slowing model, but the reliability of these effects was substantially lower than the reliability of the other task-related variables.

Adult age differences in letter-level and word-level processing.

Older and young adults' letter detection and lexical decision performance were examined as word frequency varied to determine whether there were age differences in word recognition. Allen and Madden (1989) found that older adults' pattern of reaction time (RT) across word frequency categories was different from young adults' pattern for a letter detection task. In this study, for both letter detection and lexical decision tasks, older adults exhibited a monotonically decreasing RT function as word frequency increased. However, young adults exhibited a nonmonotonic RT function across word frequency for the letter detection task but a monotonically decreasing RT function as word frequency increased for the lexical decision task. An expanded parallel input serial analysis model of word processing was hypothesized.

On mental multiplication and age.

In 2 experiments, younger and older adults were presented with simple multiplication problems (e.g., 4 x 7 = 28 and 5 x 3 = 10) for their timed, true or false judgments. All of the effects typically obtained in basic research on mental arithmetic were obtained, that is, reaction time (a) increased with the size of the problem, (b) was slowed for answers deviating only a small amount from the correct value, and (c) was slowed when related (e.g., 7 x 4 = 21) versus unrelated (e.g., 7 x 4 = 18) answers were presented. Older adults were slower in their judgments. Most important, age did not interact significantly with problem size or split size. The authors suggest that elderly adults' central processes, such as memory retrieval and decision making, did not demonstrate the typical age deficit because of the skilled nature of these processes in simple arithmetic.

Adult age differences in attentional allocation during memory search.

Young and older adults performed a memory search task in which, before probe onset, a cue indicated which of 4 memory-set items the probe was most likely to be. The results were consistent with an attentional allocation model in which performance represents a weighted combination, across trials, of focused (i.e., selective) versus distributed attention. The model significantly underestimated the reaction time required by miscued trials, probably because of the response inhibition occurring on these trials. The degree to which Ss relied on focused attention was significantly greater for older adults than for young adults. The estimated time required to shift attention between memory-set items was equivalent for the 2 age groups.

Adult age differences in the use of distractor homogeneity during visual search.

Previous research has suggested that an age-related decline may exist in the ability to inhibit distracting information during visual search. The present experiments used a conjunction search task in which the within-item features of the target (an upright L) and the distractors (rotated Ls) were identical. In each of 2 experiments, both young and older adults searched the display significantly more rapidly when the distractors were all rotated in the same direction (homogeneous) than when the distractors were rotated in different directions (heterogeneous). The concept of a generalized, age-related slowing was able to account for many aspects of the data, although the degree of relative improvement associated with distractor homogeneity was greater for young adults than for older adults.

A molar entropy model of age differences in spatial memory.

Two very-short-term-memory, spatial scanning aging experiments were conducted involving a graphics character as a target stimulus. On the probe portion of a trial, the stimulus was presented in the same position as it was on the target portion of the trial (i.e., a same trial) 50% of the time. However, on the remaining 50% of the trials, the probe stimulus was shifted (or transposed) 1, 2, or 3 positions to the right or left of the original presentation (target) position. In Experiment 1, exposure duration was manipulated. In Experiment 2, the number of potential target display positions was manipulated. For both experiments, older adults showed larger transposition distance effects than younger adults for errors. In the past (e.g., P.A. Allen, 1990, 1991), this effect has been attributed to higher levels of internal noise (entropy) in older than younger adults. This research provides converging operations to this contention by using statistical physics methods to rigorously compute the entropy in a molar neural network across age groups. After successfully fitting the statistical mechanics model to the data, the model is proved to have external validity by fitting a simplified version of it to an earlier spatial memory aging experiment reported by P. R. Bruce and J. F. Herman (1986). The results of both traditional reaction time and error rate analyses, as well as the entropy modeling analyses, indicated that older adults exhibited higher levels of entropy than did the younger adults and that this effect appeared to be generalized across processing stage.

The psychological refractory period: evidence for age differences in attentional time-sharing.

The authors report 2 psychological refractory period (PRP) experiments in which the stimulus onset asynchrony (SOA) between Task 1 and Task 2 was 150 ms, 250 ms, 600 ms, and 1,100 ms for both younger and older adults. H. Pashler's (1994a) response-selection bottleneck theory predicts that SOA manipulations should not affect Task 1 performance, but that reaction time (RT) for Task 2 should increase as the SOA between the 2 tasks decreases (i.e., the classical PRP effect). In Experiment 1 (Task 1 = tone discrimination, Task 2 = dot location), older adults showed a larger PRP effect than younger adults did, although Task 1 RT was affected by SOA, suggesting that participants were grouping their responses on some trials. That is, participants were holding their response for Task 1 until they had completed processing Task 2, and then they responded to both tasks almost simultaneously. However, a subset of participants (11 younger adults and 11 older adults) who showed no evidence of response grouping on Task 1 continued to show a larger PRP effect for older adults on Task 2. In Experiment 2 (Task 1 = dot location, Task 2 = simultaneous letter matching), older adults continued to show a larger PRP effect than younger adults for Task 2, and Task 1 performance was unaffected by SOA. Consequently, these experiments provide evidence that older adults (relative to younger adults) exhibit a decrement in time-sharing at the response-selection stage of processing. These results suggest that attentional time-sharing needs to be added to the list of topics examined in aging research on varieties of attention.

Adult age differences in visual search accuracy: attentional guidance and target detectability.

Previous research, relying primarily on reaction time measures of highly accurate performance, suggests that both younger and older adults can increase the efficiency of visual search by guiding attention to a candidate subset of items. The authors investigated attentional guidance when accuracy was well below ceiling to focus more specifically on the role of perceptual processes. In the most difficult condition (conjunction search), the likelihood of missing a target was greater for older adults than for younger adults, and this effect was not attributable entirely to generalized slowing. Both age groups were able to improve search efficiency by attending to a distinct subset of display items, indicating that attentional guidance to perceptual features does not exhibit age-related decline. A signal-detection model of the conjunction search data demonstrated that the age difference represented an age-related decline in target detectability.

Influence of adult age on primary and secondary memory search.

We compared young and elderly adults on the ability to search lists of words stored in primary memory (PM) and in secondary memory (SM). The results of Experiment 1 indicated that age differences in search performance were greatest under SM conditions. Older adults, unlike the young, appeared biased toward responding that probe items were not members of the memory sets stored in SM. As a result of this apparent bias, older adults committed a large number of errors on trials in which the probe was a member of the memorized list (i.e., positive probe trials) yet few errors on trials in which the probe was not a member of the list (i.e., negative probe trials). In addition, the responses of older, but not younger, adults to negative probe trials were found to be more rapid than were those to positive probe trials. In Experiment 2 we examined this pattern of responding and concluded that age differences were involved in the ability to encode memory sets and transfer them from PM to SM as well as in the ability to retrieve information from SM prior to conducting a memory search.

Influence of age and processing stage on visual word recognition.

The authors used a lexical-decision task in 3 different experiments to examine whether age differences in word recognition were consistent across processing stage. In all experiments, word frequency and length were manipulated. In Experiments 1 and 2, encoding difficulty was varied, and in Experiment 3, response selection difficulty was varied. In all 3 experiments, there were no age differences for word frequency. However, in Experiments 1 and 2, older adults showed a larger decrement for encoding. In Experiment 3, age differences were larger when response selection load increased. These results suggest that age differences in word recognition occur because older adults exhibit primarily peripheral-rather than central-processing decrements. The implications of these data for generalized and localized slowing models are discussed.

Improving aerobic capacity in healthy older adults does not necessarily lead to improved cognitive performance.

The effects of aerobic exercise training in a sample of 85 older adults were investigated. Ss were assigned randomly to either an aerobic exercise group, a nonaerobic exercise (yoga) group, or a waiting-list control group. Following 16 weeks of the group-specific protocol, all of the older Ss received 16 weeks of aerobic exercise training. The older adults demonstrated a significant increase in aerobic capacity (cardiorespiratory fitness). Performance on reaction-time tests of attention and memory retrieval was slower for the older adults than for a comparison group of 24 young adults, and there was no improvement in the older adults' performance on these tests as a function of aerobic exercise training. Results suggest that exercise-related changes in older adults' cognitive performance are due either to extended periods of training or to cohort differences between physically active and sedentary individuals.

How shared are age-related influences on cognitive and noncognitive variables?

Several theories have suggested that age-related declines in cognitive processing are due to a pervasive unitary mechanism, such as a decline in processing speed. Structural equation model tests have shown some support for such common factor explanations. These results, however, may not be as conclusive as previously claimed. A further analysis of 4 cross-sectional data sets described in Salthouse, Hambrick, and McGuthry (1998) and Salthouse and Czaja (2000) found that although the best fitting model included a common factor in 3 of the data sets, additional direct age paths were significant, indicating the presence of specific age effects. For the remaining data set, a factor-specific model fit at least as well as the best fitting common factor model. Three simulated data sets with known structure were then tested with a sequence of structural equation models. Common factor models could not always be falsified--even when they were false. In contrast, factor-specific models were more easily falsified when the true model included a unitary common factor. These results suggest that it is premature to conclude that all age-related cognitive declines are due to a single mechanism. Common factor models may be particularly difficult to falsify with current analytic procedures.

Age differences in mental multiplication: evidence for peripheral but not central decrements.

This study reports two mental multiplication experiments that were designed to measure age differences in central and peripheral processes. Experiment 1 varied task type (verification vs production), and Experiment 2 varied exposure duration (presentation until response, 600 ms, and 300 ms) on a production task. Neither experiment showed evidence of age differences in central processes (e.g., retrieval speed); however, there was some evidence of a peripheral-process (e.g., encoding) decrement for older adults. Specifically, there were no Age X Problem Size interactions for either experiment. Experiment 2 revealed decreasing age differences as problem difficulty increased. Indeed, for the 300-ms exposure duration, there were no age differences in RT or error rate. These results suggest that the magnitude of age differences in central processing speed are significantly less extreme than are age differences for peripheral processing speed for this type of mental arithmetic task. Also, older adults, in general, may have a higher skill level for basic fact retrieval in mental arithmetic than do young adults.

Hypnotic susceptibility, imaging ability, and the detection of embedded words within letters.

Two experiments were conducted to determine the role of hypnotic susceptibility level (high or low) and imaging ability (vivid or poor) in the performance of a visual search for words embedded within matrices of letters. In Experiment 1, subjects searched for target words from a list; however, distractor words were also embedded in the matrices. Results indicated that subjects judged both high in hypnotic susceptibility and vivid in imaging ability demonstrated the fastest search speed with a greater percentage of target words found. These subjects also made fewer false alarm errors (locating distractor words not on the target list). The poorest performance was exhibited by subjects judged both low in hypnotic susceptibility and poor in imaging ability. The amount of variance accounted for by hypnotic susceptibility and imaging ability was approximately equal for each dependent measure. In Experiment 2, when subjects searched for target words from a list without distractor words embedded in matrices, similar results to those reported for Experiment 1 were produced, except that the percentage of words found was equivalent across groups. This was attributed to the elimination of potential false alarm errors. The results are explained in terms of the use of either a holistic or a detail strategy in the performance of a visual search.

Hypnotic susceptibility, imaging ability, and anagram-solving activity.

Anagram-solving activity was examined as a function of hypnotic susceptibility level and imaging ability. In Experiment 1, anagrams that were composed of sets of letters that formed actual words (word anagrams), but when unscrambled formed other words, were compared to sets of letters that formed nonwords (nonsense anagrams). Word anagrams required more time to solve than nonsense anagrams. Also, fewer word anagrams were correctly solved compared to nonsense anagrams. Those individuals judged both high in hypnotic susceptibility and vivid in imaging ability demonstrated the best performance. In Experiment 2, anagrams that when unscrambled formed high-imagery words were compared to those that formed low-imagery words. High-imagery-word anagrams were solved more quickly and correctly than low-imagery-word anagrams. Such activity was best demonstrated by individuals who were judged to be both high in hypnotic susceptibility and vivid in imaging ability. These results are discussed in terms of strategies for solving anagrams and the individual differences that appear to be associated with using such strategies.