Age-Related Declines in Context Maintenance and Semantic Short-Term Memory

Event Segmentation Enhances Older Adults' Reactive Cognitive Control Bias

The present study examined the effect of event segmentation on cognitive control mode use in a sample of older adults (N = 30; Mage = 73, SDage = 4.75) using a modified AX-Continuous Performance Test (AX-CPT). This task included a perceptual event boundary between each cue and its forthcoming probe by means of a spatial shift across the left and right side of the display. Past research showed that young adults' existing proactive control bias could be enhanced in an event segmented AX-CPT relative to their performance on a standard AX-CPT. For older adults who adopt reactive control by default, the event boundary was expected to impede cue-reactivation during probe presentation, and thus further enhance their existing reactive control bias. To examine this, older adults were tested with a standard and an event segmented AX-CPT in two blocks, with error rates revealing a shift toward greater reactive control use in the event segmented relative to the standard AX-CPT. Findings supported our hypothesis that placing a spatial event boundary between each cue and forthcoming probe would further enhance older adults' reactive control bias. This study contributes to the sparse but growing literature on the effects of task-specific manipulations on cognitive control use. The results are discussed in light of the dual mechanisms of control framework and the event horizon model.

Effects of task types and time interval conditions on age-related decline in verbal working memory

Age-related differences in working memory (WM) components were investigated by manipulating the time interval and interference effects between phonological and semantic judgment tasks to identify tasks to best discriminate between younger and older groups. The 96 participants (young = 48; old = 48) prospectively performed two task types of WM, with phonological and semantic judgment tasks, which were administered while varying the three interval conditions: 1-s unfilled (UF), 5-s UF, and 5-s filled (F). The main effect for age was significant in the semantic judgment task but not in the phonological judgment task. The main effect for the interval conditions were significant in both tasks. A 5-s UF condition applied to a semantic judgment task could significantly differentiate the older group from the younger group. Differential effects of time interval manipulation in semantic and phonological processing are involved in WM resources. The older group could be differentiated by varying the task types and interval conditions, indicating that the semantic-related WM burdens may contribute to a superior differential diagnosis of aging-related WM decline.

The effect of aging on context use and reliance on context in speech: A behavioral experiment with Repeat–Recall Test

Purpose

To elucidate how aging would affect the extent of semantic context use and the reliance on semantic context measured with the Repeat–Recall Test (RRT).

Methods

A younger adult group (YA) aged between 18 and 25 and an older adult group (OA) aged between 50 and 65 were recruited. Participants from both the groups performed RRT: sentence repeat and delayed recall tasks, and subjective listening effort and noise tolerable time, under two noise types and seven signal-to-noise ratios (SNR). Performance–Intensity curves were fitted. The performance in SRT50 and SRT75 was predicted.

Results

For the repeat task, the OA group used more semantic context and relied more on semantic context than the YA group. For the recall task, OA used less semantic context but relied more on context than the YA group. Age did not affect the subjective listening effort but significantly affected noise tolerable time. Participants in both age groups could use more context in SRT75 than SRT50 on four tasks of RRT. Under the same SRT, however, the YA group could use more context in repeat and recall tasks than the OA group.

Conclusion

Age affected the use and reliance of semantic context. Even though the OA group used more context in speech recognition, they failed in speech information maintenance (recall) even with the help of semantic context. The OA group relied more on context while performing repeat and recall tasks. The amount of context used was also influenced by SRT.

Age-Related Changes in Verbal Working Memory Strategies

Background/Study context: Maintenance in verbal working memory is thought to rely on two main systems: a phonological and a semantic system. The three objectives of the present study were to clarify how these systems are organized and interact, to examine whether their involvement in maintenance changes with aging, and to identify which underlying mechanism accounts for both age-related changes in the available set of mechanisms and immediate recall.Methods: To address these issues, we examined age-related changes in strategic aspects of maintenance of information in working memory. We collected trial-by-trial verbal reports of which strategy young and older adults used while accomplishing a verbal complex span task. In addition, individuals' speed of articulation was collected.Results: Results support the existence of separable systems (i.e., phonological and semantic systems) that participants combine to cope with increasing memory loads. We also found age-related differences (e.g., older individuals used more strategies than young individuals and used available strategies unequally often) and invariance (e.g., both age groups used strategies based on phonological and semantic processing) in strategic aspects of working memory maintenance. Importantly, articulation speed accounted for effects of both memory load and age on strategy distributions as well as for age-related differences in immediate recall.Conclusion: Our findings suggest that young and older adults' use of common and different sets of maintenance mechanisms stems for the constraints of the phonological loop in working memory, especially the speed of articulation, which slowed down with aging.

Preserved Proactive Control in Ageing: A Stroop Study With Emotional Faces vs. Words

Previous studies regarding age-related changes in proactive control were inconclusive and the effects of emotion on proactive control in ageing are yet to be determined. Here, we assessed the role of task-relevant emotion on proactive control in younger and older adults. Proactive control was manipulated by varying the proportion of conflict trials in an emotional Stroop task. In Experiment 1, emotional target faces with congruent, incongruent or non-word distractor labels were used to assess proactive control in younger and older adults. To investigate whether the effects of emotion are consistent across different stimulus types, emotional target words with congruent, incongruent or obscured distractor faces were used in Experiment 2. Data from this study showed that older adults successfully deployed proactive control when needed and that task-relevant emotion affected cognitive control similarly in both age groups. It was also found that the effects of emotion on cognitive performance were qualitatively different for faces and words, with facilitating effects being observed for happy faces and for negative words. Overall, these results suggest that the effects of emotion and age on proactive control depend on the task at hand and the chosen stimulus set.

Effects of Aging and Dual-Task Demands on the Comprehension of Less Expected Sentence Continuations: Evidence From Pupillometry

Prior studies on language processing in aging have shown that older adults experience integration difficulties for contextually unpredictable target words (as indicated by low cloze probabilities in prior ratings), and that such comprehension difficulties are more likely to occur under more demanding processing conditions (e.g., dual-task situations). However, these effects have primarily been demonstrated for conditions when cloze probability of the linguistic stimuli was very low. The question we asked here was do dual-task demands also impair comprehension when target words provide a good, but not perfect, match with prior context? We used a dual-task design, consisting of a sentence comprehension and secondary motor tracking task. Critical target words were those which were not perfectly predictable based on context (words with a cloze probability of 0.7), as opposed to words that were near perfectly predictable based on context (cloze probabilities of 0.99). As a measure to index online processing difficulty for less expected target words, we took into account participants' pupil size. Separate mixed effects models were fit for language comprehension, motor tracking, and pupil size, showing the following: (1) dual-task demands led to age-related comprehension difficulties when target words were less expected (as opposed to very highly expected), (2) integration difficulty in older adults was related to cognitive overload as less expected sentence continuations progressed over time, resulting in behavioral trade-offs between language comprehension and motor tracking, and (3) lower levels of working memory were predictive of whether or not older adults experienced cognitive overload when processing less expected words. In sum, more demanding processing conditions lead to comprehension impairments when words are highly unpredictable based on context, as many prior studies showed. Comprehension impairments among older individuals also occur for conditions when words provide a good, but not perfect, match with prior context. Higher working memory capacity can alleviate such impairments in older adults, thereby suggesting that only high-WM older adults have sufficient cognitive resources to pre-activate words that complete a sentence context plausibly, but not perfectly.

A new index of semantic short-term memory: Development and validation of the conceptual span task in Spanish

Mounting evidence from both cognitive and neuropsychological research points to the importance of conceptual and lexical-semantic contributors to short-term memory performance. Nonetheless, a standardized and well-controlled measure to assess semantic short-term memory was only recently developed for English-speakers, and no parallel measure exists for Spanish-speakers. In the conceptual replication and extension reported here, we develop and validate a Spanish adaptation of the Conceptual Span task as a tool to measure the semantic component of short-term memory. Two versions of the task were validated, the Clustered and the Non-Clustered Conceptual Span task, both in separate samples of 64 and 105 Spanish-speaking university students. We found that both versions of the Conceptual Span task correlate well with another widely used standardized measure of working memory capacity, the Reading Span task. The two versions also correlated, as expected, with discrimination of linguistic congruency as assessed by a semantic anomaly judgment task. Clustered Conceptual Span remained a significant predictor of Reading Span when controlling for several additional cognitive variables, including fluid reasoning, text comprehension, verbal fluency, ideational fluency, and speed of processing. Our results present evidence that the Spanish adaptation of both versions of the Conceptual Span task can yield reliable estimates of the active maintenance of semantic representations in verbal working memory–an under-investigated ability that is involved in diverse domains such as episodic memory retrieval, language processing, and comprehension. Thus, the Conceptual Span task validated here can be employed to predict individual variation in semantic short-term memory capacity in a broad range of research domains.

Age-Related Deficits in Memory Encoding and Retrieval in Word List Free Recall

Although ageing is known to affect memory, the precise nature of its effect on retrieval and encoding processes is not well understood. Here, we examine the effect of ageing on the free recall of word lists, in which the semantic structure of word sequences was manipulated from unrelated words to pairs of associated words with various separations (between pair members) within the sequence. We find that ageing is associated with reduced total recall, especially for sequences with associated words. Furthermore, we find that the degree of semantic clustering (controlled for chance clustering) shows an age effect and that it interacts with the distance between the words within a pair. The results are consistent with the view that age effects in memory are mediated both by retrieval and by encoding processes associated with frontal control and working memory.

Designing Wearable Technology for an Aging Population

When considering the future and application of wearable technological devices, the growing demographic of adults over the age of 65 should be included during the product design process. Wearable technology could provide an ideal mechanism for delivering supportive applications to a growing older adult population, but designers must consider age-related changes in cognitive, sensory, and motor function when developing for older populations. Potential issues with wearable devices for older adults can be avoided by acknowledging limitations, and development teams can create effective and safe platforms that appeal to a variety of end users.

The role of the frontal cortex in memory: an investigation of the Von Restorff effect

Evidence from neuropsychology and neuroimaging indicate that the pre-frontal cortex (PFC) plays an important role in human memory. Although frontal patients are able to form new memories, these memories appear qualitatively different from those of controls by lacking distinctiveness. Neuroimaging studies of memory indicate activation in the PFC under deep encoding conditions, and under conditions of semantic elaboration. Based on these results, we hypothesize that the PFC enhances memory by extracting differences and commonalities in the studied material. To test this hypothesis, we carried out an experimental investigation to test the relationship between the PFC-dependent factors and semantic factors associated with common and specific features of words. These experiments were performed using Free-Recall of word lists with healthy adults, exploiting the correlation between PFC function and fluid intelligence. As predicted, a correlation was found between fluid intelligence and the Von-Restorff effect (better memory for semantic isolates, e.g., isolate “cat” within category members of “fruit”). Moreover, memory for the semantic isolate was found to depend on the isolate's serial position. The isolate item tends to be recalled first, in comparison to non-isolates, suggesting that the process interacts with short term memory. These results are captured within a computational model of free recall, which includes a PFC mechanism that is sensitive to both commonality and distinctiveness, sustaining a trade-off between the two.

Rapid communication: Integrating working memory capacity and context-processing views of cognitive control

Individuals low in working memory capacity (WMC) exhibit impaired performance on a variety of cognitive control tasks. The executive-attention theory of WMC (Engle & Kane, [2004[) accounts for these findings as failures of goal maintenance and response conflict resolution. Similarly, the context-processing view (Braver et al., [2001]) provides an explanation of cognitive control deficits observed in schizophrenia patients and older adults that is based on the ability to maintain context information. Instead of maintenance deficits, the inhibition view (Hasher, Lustig, & Zacks, [2007]) states that older adults and individuals low in WMC primarily have an impairment in the ability to inhibit information. In the current experiment, we explored the relationships among these theories. Individuals differing in performance on complex span measures of WMC performed the AX-Continuous Performance Test to measure context-processing performance. High-WMC individuals were predicted to maintain the context afforded by the cue, whereas low-WMC individuals were predicted to fail to maintain the context information. Low-WMC individuals made more errors on AX and BX trials and were slower to respond correctly on AX, BX, and BY trials. The overall pattern of results is most consistent with both the executive-attention and context-processing theories of cognitive control.

Pupillometric and behavioral markers of a developmental shift in the temporal dynamics of cognitive control

The capacity to anticipate and prepare for future events is thought to be critical for cognitive control. Dominant accounts of cognitive control treat the developing system as merely a weaker version of the adult system, progressively strengthening over time. Using the AX Continuous Performance Task (AX-CPT) in combination with high-resolution pupillometry, we find that whereas 8-year-old children resemble adults in their proactive use of cognitive control, 3.5-year-old children exhibit a qualitatively different, reactive form of cognitive control, responding to events only as they unfold and retrieving information from memory as needed in the moment. These results demonstrate the need to reconsider the origins of cognitive control and the basis for children's behaviors across domains.

The Model Human Processor and the older adult: parameter estimation and validation within a mobile phone task

The authors estimate weighted mean values for nine information processing parameters for older adults using the Card, Moran, and Newell (1983) Model Human Processor model. The authors validate a subset of these parameters by modeling two mobile phone tasks using two different phones and comparing model predictions to a sample of younger (N = 20; M-sub(age) = 20) and older (N = 20; M-sub(age) = 69) adults. Older adult models fit keystroke-level performance at the aggregate grain of analysis extremely well (R = 0.99) and produced equivalent fits to previously validated younger adult models. Critical path analyses highlighted points of poor design as a function of cognitive workload, hardware/software design, and user characteristics. The findings demonstrate that estimated older adult information processing parameters are valid for modeling purposes, can help designers understand age-related performance using existing interfaces, and may support the development of age-sensitive technologies.

The validity of "conceptual span" as a measure of working memory capacity

Three experiments tested whether a modified version of the Clustered Conceptual Span task (H. J. Haarmann, E. J. Davelaar, & M. Usher, 2003), which ostensibly requires active maintenance of semantic representations, predicted individual differences in higher-order cognitive abilities better than short-term memory (STM) span tasks or nonsemantic versions of the "Conceptual" task did. Nonsemantic Conceptual tasks presented short word lists clustered by color, first letter, or initial vowel sound, and cued subjects to recall only 1 of 3 clusters from each list; the Semantic task clustered words by taxonomic category. The Semantic Conceptual task generally failed to predict incremental variance in either verbal abilities or general fluid intelligence beyond the other Conceptual tasks or STM span tasks. Although the Semantic task showed a stronger relation to working memory span tasks than did the nonsemantic tasks (Experiment 3), that stronger relation did not translate into strong prediction of cognitive individual differences.

The elusive nature of executive functions: a review of our current understanding

Executive functions include abilities of goal formation, planning, carrying out goal-directed plans, and effective performance. This article aims at reviewing some of the current knowledge surrounding executive functioning and presenting the contrasting views regarding this concept. The neural substrates of the executive system are examined as well as the evolution of executive functioning, from development to decline. There is clear evidence of the vulnerability of executive functions to the effects of age over lifespan. The first executive function to emerge in children is the ability to inhibit overlearned behavior and the last to appear is verbal fluency. Inhibition of irrelevant information seems to decline earlier than set shifting and verbal fluency during senescence. The sequential progression and decline of these functions has been paralleled with the anatomical changes of the frontal lobe and its connections with other brain areas. Generalization of the results presented here are limited due to methodological differences across studies. Analysis of these differences is presented and suggestions for future research are offered.

Impaired psychological recovery in the elderly after the Niigata-Chuetsu Earthquake in Japan:a population-based study

BACKGROUND

An earthquake measuring 6.8 on the Richter scale struck the Niigata-Chuetsu region of Japan at 5.56 P.M. on the 23rd of October, 2004. The earthquake was followed by sustained occurrence of numerous aftershocks, which delayed reconstruction of community lifelines. Even one year after the earthquake, 9,160 people were living in temporary housing. Such a devastating earthquake and life after the earthquake in an unfamiliar environment should cause psychological distress, especially among the elderly.

METHODS

Psychological distress was measured using the 12-item General Health Questionnaire (GHQ-12) in 2,083 subjects (69% response rate) who were living in transient housing five months after the earthquake. GHQ-12 was scored using the original method, Likert scoring and corrected method. The subjects were asked to assess their psychological status before the earthquake, their psychological status at the most stressful time after the earthquake and their psychological status at five months after the earthquake. Exploratory and confirmatory factor analysis was used to reveal the factor structure of GHQ12. Multiple regression analysis was performed to analyze the relationship between various background factors and GHQ-12 score and its subscale.

RESULTS

GHQ-12 scores were significantly elevated at the most stressful time and they were significantly high even at five months after the earthquake. Factor analysis revealed that a model consisting of two factors (social dysfunction and dysphoria) using corrected GHQ scoring showed a high level of goodness-of-fit. Multiple regression analysis revealed that age of subjects affected GHQ-12 scores. GHQ-12 score as well as its factor 'social dysfunction' scale were increased with increasing age of subjects at five months after the earthquake.

CONCLUSION

Impaired psychological recovery was observed even at five months after the Niigata-Chuetsu Earthquake in the elderly. The elderly were more affected by matters relating to coping with daily problems.