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.

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.

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.

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.

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.

Age differences in entropy: primary versus secondary memory.

We report a spatial-memory scanning experiment that was used to measure age differences in entropy. A target grid consisting of four adjacent letters followed by the presentation of a single probe letter was presented on each trial. Half of the trials presented the probe stimulus in the same spatial position was the target letter (i.e., the probe letter was always a member of the positive set), and half of the trials transposed the target letter one, two, or three spaces of the right or left of the original target display position (i.e., different trials). The experiment involved blocks of primary-memory and secondary-memory tasks. Reaction-time and error-rate data, as well as entropy analyses and the fitting of an entropy model (based on Allen, Kaufman, Smith, and Propper, in press) to the empirical data indicated that older adults showed higher entropy levels than young adults. These results are interpreted in a "computational temperature" framework in which older adults' higher computational temperatures result in less efficient spatial, episodic memory functioning.

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 long-term semantic priming.

Young and older adults were first asked to decide if a list of individually presented words were "living" (e.g., "tree") or "nonliving" (e.g., "store"). This was termed the "orienting task." Next, subjects performed a pronunciation task. Semantic priming for young and older adults was indexed by determining if semantic congruence between words in the orienting task and words in the pronunciation task improved performance on the pronunciation task relative to pronounced words from semantic categories not primed in the orienting task. The present data, from two different experiments, revealed that subjects pronounced high-dominance exemplars of the "living" words primed in the orienting task faster than words not primed in the orienting task. These data indicated that semantic priming for relatively long prime-target stimulus onset asynchronies can occur, and that such priming is at least as robust for older adults as for young adults. The results are discussed in terms of four current models of semantic priming.

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.

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.

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.

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.

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).

Aging and the speed/accuracy relation in visual search: evidence for an accumulator model.

Two models of performance in visual classification tasks, the fast-guess model and the accumulator model, offer contrasting accounts of the relation between speed and accuracy. We attempted to distinguish these models in the context of age-related changes in visual search performance. Twenty-four young adults (mean age 21.50 years) and 24 older adults (mean age 66.17 years) performed a visual search task requiring the detection of an upright L among rotated L's. The results supported the accumulator model, in that mean reaction time (RT) was higher for error responses than for correct responses, and there was a positive relation between RT and error rate. Both of these effects were more pronounced for older adults than for young adults, even when visual acuity was covaried statistically. We conclude that age-related changes in visual search performance involve a decline in the efficiency of sampling the amount of evidence necessary to exceed a decision criterion.

Adult age differences in attention: filtering or selection?

We examined the effect of target letter redundancy for target-only (TO) and target-plus-noise (TPN) trials on a visual search, divided attention task where target letters were presented in one or two corners of a two-corner display. Half of the two-letter displays also included a noise letter. In both Experiment 1 (two-choice vs go/no-go) and Experiment 2 (all go/no-go), older adults showed larger redundancy gains than did young adults, and this effect did not interact with task type or visual similarity. However, for the "no-go" trials in both experiments, there were no age differences in overall errors. These results suggest that there are age differences in the activation of selective attention rather than age differences in inhibitory control. In Experiment 2, young adults under lower-luminance presentation conditions (18 cd/m2) showed a smaller redundancy gain than did older adults under higher-luminance presentation conditions (40 cd/m2). These results provided further support of the age differences in activation interpretation, as well as indicating that older adults' larger redundancy gain was not due to an age decrement in retinal illuminance.

Influence of imaging ability on word transformation.

In the present study, we examined whether individual differences in imaging ability affect visual word recognition. Poor and vivid imagers performed a naming task that involved nonreversed (e.g., JUMP) and reversed (e.g., PMUJ) words (Experiment 1). Poor and vivid imagers were also tested on a naming task that was controlled for verbal ability; all the words were reversed and presentation time was varied (Experiment 2). In both experiments, imaging ability interacted with task difficulty, suggesting that individual differences in imaging ability affect visual word recognition. Specifically, the present data suggest that poor imagers may be less efficient than vivid imagers at processing words analytically. The data are interpreted within a limited-capacity, hybrid, word recognition model, in which words can be processed as either word-level or letter-level codes.

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.

Influence of letter size on age differences in letter matching.

We tested healthy young and older adults on a simultaneous presentation, letter-matching task that varied letter size. The goal of the experiment was to determine if older adults' higher baseline level of internal noise would affect age differences in letter-matching performance as letter size was varied. The results indicated that both young and older adults evidenced "fast-same" effects for RT and "false-different" effects for errors. However, older adults (compared to young adults) showed a larger "false-different" effect for errors, and this effect was especially pronounced for smaller letter pairs. These results imply that older adults' higher baseline levels of internal noise result in these individuals setting "compromise criteria" that underestimate the impact of internal noise.

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.

Influence of response selection and noise similarity on age differences in the redundancy gain.

We examined the impact of target redundancy for target-plus-noise (TPN) and target-only (TO) trials. Experiment 1 manipulated response selection load (two-choice vs go/no-go) and Experiment 2 (all two-choice) varied noise redundancy (single or cumulative noise letters) on a visual search, divided attention task in which target letters were presented in one, two, or three corners of a four-corner display. Half of the trials also included noise letters. For Experiment 1, there was a definite redundancy gain for TO trials. Furthermore, older adults, relative to young adults, evidenced an even larger redundancy gain for TO trials than for TPN trials, although response selection load did not interact with age. These results are consistent with the notion that older adults exhibit a processing resources decrement. For Experiment 2, older adults evidenced a relatively larger redundancy gain for TPN trials than for TO trials, and this was especially the case for TPN trials in which all nontarget locations were filled with noise letters. Experiment 2 results are consistent with the notion that older adults also exhibit a selective attention decrement.