Aging and time-sharing aspects of executive control

A particularly important aspect of executive functioning involves the ability to coordinate two simultaneous activities. The role of this aspect of executive functioning in adult-age differences in cognitive performance was examined in a study involving 150 adults between 20 and 91 years of age who performed the same visual-motor tracking task with three different primary tasks. The participants also performed several additional cognitive tasks that allowed examination of the relation of time-sharing efficiency to other types of cognitive functioning The results were consistent with the existence of a distinct time-sharing ability because the time-sharing costs in the three dual-task combinations were significantly correlated with one another but only weakly correlated with other cognitive variables. Increased age was associated with reductions in time-sharing ability, and greater efficiency in performing two tasks at once was associated with better performance on tasks assessing spatial, reasoning, and memory abilities. Although this pattern is what one would expect if executive processes contribute to age differences in cognitive functioning, the effects were smaller than those associated with a perceptual speed construct.     

Aging, exercise, and attention.

The authors investigated the relationship among aging, attentional processes, and exercise in 2 experiments. First they examined age differences on 2 attentional tasks, a time-sharing task and an attentional flexibility task. Young adults alternated attention between 2 sequenced tasks more rapidly and time-shared the processing of 2 tasks more efficiently than older adults. They then investigated the effects of aerobic exercise on the same 2 attentional tasks in older adults. Following the 10-week exercise program, older exercisers showed substantially more improvement in alternation speed and time-sharing efficiency than older controls. Interestingly, this exercise effect was specific to dual-task processing. Both groups of subjects showed equivalent effects on single-task performance. These results indicate that aerobic exercise can exert a beneficial influence on the efficiency of at least 2 different attentional processes in older adults.     

The effects of age and professional expertise on working memory performance

Differences in professional choice and experience may explain age differences in working memory performance of elderly people. The aim of this study was to examine whether expertise and prolonged practice in verbal and visuo‐spatial abilities reduce age differences in laboratory working memory tasks. The effects of age and expertise on working memory performance were examined in three age groups in two different experiments. Firstly, the role of visuo‐spatial expertise was analysed by examining age differences in architects. Secondly, people with extensive experience in verbal abilities (literary people) were tested in order to evaluate the effect of professional verbal experience. Architects and literary people outperformed a group of unselected age peers on tasks related to professional expertise only, but not on general working memory tests. There was no interaction between age and experience, suggesting that professional experience does not increase differences between experts and non experts and cannot modulate age‐related effects. Copyright © 2008 John Wiley & Sons, Ltd.     

Age trends in children's time-sharing performance

To investigate developmental differences in time-sharing performance, 60 boys, 20 in each of three age groups (7-, 10-, and 13-year-olds) performed an auditory matching task and a tracking task alone and concurrently, the latter under two sets of instructions. Decrements produced by concurrent performance were compared for the three age groups. When the time-shared tasks were presented as equally important, time-sharing produced significantly greater proportional decrements in the tracking performance of the younger children and for all age groups tracking task decrements were directly related to matching task difficulty. Subsequently, the children were instructed that one or the other of the tasks was more important and that they were to improve their performance on that task. All three age groups showed a significant improvement on the task emphasized by instructions. The relationship of the results to two models of information processing is discussed.     

Executive-process interactive control: A unified computational theory for answering 20 questions (and more) about cognitive ageing

Although the effects of ageing on human information processing and performance have been studied extensively, many fundamental questions about cognitive ageing remain to be answered definitively. For example, what are the sources of age-related slowing? How much is working-memory capacity reduced in older adults? Is time-sharing ability lost with age? Answering such questions requires a unified computational theory that characterises the interactive operations of many component mental processes and integrates diverse data on cognitive ageing. Toward fulfilling this requirement, an executive-process interactive control (EPIC) architecture has been extended to model performance of both young and older adults. EPIC models yield accurate accounts of ageing effects on reaction times and accuracy in basic dual-task and working-memory paradigms. From these accounts, it appears that time-sharing ability and working-memory capacity decrease relatively little until after 70 years of age. Before age 70, at least some apparent performance decrements may be attributable to conservative executive processes and inefficient task procedures rather than decreased "hardware" functionality. By clarifying and deepening such insights, unified computational theories like EPIC will help answer many questions about cognitive ageing.     

Baseline differences,attention, and age differences in time-sharing performance

The purpose of this experiment was to determine whether age differences noted when two tasks are performed concurrently can be accounted for in terms of age differences in single task baseline performance. Two groups of 12 8-year-olds and one group of 12 13-year-olds performed a compensatory tracking task and an auditory matching task, first alone and then time shared. The 8- and 13-year-old baseline groups performed baseline trials on each task prior to time-sharing trials. Each training group 8-year-old was randomly paired with a 13-year-old and given sufficient single task practice before time sharing to equate the 8- and 13-year-old pair members' baselines on both tasks. Results showed trained 8-year-olds to be indistinguishable from 13-year-olds in time sharing, whereas the 8-year-old baseline group showed significantly greater decrements in time-sharing and higher baseline scores on both tasks. These data provide support for the hypothesis that time-shared performance is directly related to level of baseline performance.     

The reliability of the time-sharing paradigm

The primary purpose of this study was to investigate the reliability of the time-sharing paradigm as a function of the age of the child and the concurrent speaking task employed. Subjects were 40 normal right-handed children, 10 at each of four age levels: 3, 5, 7, and 9. Each subject was presented with three concurrent speaking tasks, syllable repetition, sentence repetition, and story telling. There were control tapping and verbal conditions as well. The entire experimental procedure was administered two times within a 2-week interval. The principal finding of the study was that children were more likely to show the predicted asymmetry on the first administration of the paradigm than on the second one. The sentence repetition task was the one most likely to show the predicted asymmetry between hands, though children showed the most consistent performance on the syllable repetition task. Based on these findings, it was suggested that the time-sharing paradigm might not be particularly reliable in showing the predicted asymmetry in repeated administration of the same tasks with the same linguistic stimuli.     

A Bayesian approach to exploring expertise and putting success in adolescent and young adult golfers

ObjectivesPutting behaviour was examined to explore if age influenced performance and the development of motor and perceptual-cognitive expertise during late adolescence and early adulthood. We also examined if motor control and perceptual-cognitive expertise was related to performance on a representative putting task.MethodTwenty elite golfers (15 male; 17–24 years old; mean handicap of 0.5) completed eight straight and eight sloped putts at two distances (8ft/2.44m and 15ft/4.57m), on an indoor golf surface. Participants wore an eye tracker whilst putting and putting performance was assessed via putts holed and eye-movement behaviour, examining Quiet Eye (QE, the duration of the final fixation on the ball). A baseline profile for each participant was created using kinematic stroke data (collected using SAM PuttLab), average putts per round, greens in regulation and current practice hours (subjective self-report measures).ResultsBayesian statistical analysis revealed ‘moderate’ evidence that age and baseline kinematic factors did not influence putting success rates. Eye movement data revealed ‘moderate’ evidence that i) successful performance was associated with less variability in QE duration and ii) extended periods of QE were associated with a decline in performance. Previous experience and current skill level were ruled out as potential confounds.ConclusionOur findings reveal that performance and perceptual-cognitive expertise, did not improve with age. We suggest that post 18 years, age should not be considered a factor in talent development programmes for golf putting. We discuss the benefits of adopting a Bayesian approach and suggest future studies employ longitudinal designs to examine changes in expertise over time.     

Extensive occupational finger use delays age effects in tactileperception—an ERP study

Tactile expertise, resulting from extensive use of hands, has previously been shown to improve tactile perception in blind people and musicians and to be associated with changes in the central processing of tactile information. This study investigated whether expertise, due to precise and deliberate use of the fingers at work, relates to improved tactile perception and whether this expertise interacts with age. A tactile pattern and a frequency discrimination task were conducted while ERPs were measured in experts and nonexperts of two age groups within middle adulthood. Independently of age, accuracy was better in experts than in nonexperts in both tasks. Somatosensory N70 amplitudes were larger with increasing age and for experts than for nonexperts. P100 amplitudes were smaller in experts than in nonexperts in the frequency discrimination task. In the pattern discrimination task, P300 difference wave amplitude was reduced in experts and late middle-aged adults. In the frequency discrimination task, P300 was more equally distributed in late middle-aged adults. We conclude that extensive, dexterous manual work leads to acquisition of tactile expertise and that this expertise might delay, but not counteract, age effects on tactile perception. Comparable neurophysiological changes induced by age and expertise presumably have different underlying mechanisms. Enlarged somatosensory N70 amplitudes might result from reduced inhibition in older adults but from enhanced, specific excitability of the somatosensory cortex in experts. Regarding P300, smaller amplitudes might indicate fewer available resources in older adults and, by contrast, a reduced need to engage as much cognitive effort to the task in experts.     

Influence of Domain Knowledge on Monitoring Performance Across the Life Span

Two studies were conducted to investigate effects of domain knowledge on metacognitive monitoring across the life span in materials of different complexity. Participants from 4 age groups (3rd-grade children, adolescents, younger and older adults) were compared using an expert–novice paradigm. In Study 1, soccer experts’ and novices’ ease-of-learning judgments (EOLs), judgments of learning (JOLs), and confidence judgments (CJs) were contrasted when memorizing soccer-related word pairs. In Study 2, monitoring judgments (i.e., a rating of global comprehension, JOLs, and CJs) were collected in regards to a soccer-related narrative. The results of both approaches showed that experts’ better memory performance obtained in both studies was not always accompanied by advantages in monitoring performance. In Study 1, experts of all ages outperformed novices in monitoring accuracy. In Study 2, no benefits of expertise on monitoring were found; in children, novices even surpassed experts in monitoring quality. In both studies, the most consistent influence of previous domain knowledge on monitoring performance concerned more optimistic judgments of experts compared with novices, regardless of stimuli and recall format. In sum, our results document a twofold effect of expertise on monitoring. Although domain-specific knowledge enhances monitoring performance in some situations, more optimistic estimates, presumably due to the application of a familiarity heuristic, typically reduce experts’ monitoring accuracy.     

Attending to the execution of a complex sensorimotor skill: expertise differences, choking, and slumps

A simulated baseball batting task was used to compare the relative effects of attending to extraneous information (tone frequency) and attending to skill execution (direction of bat movement) on performance and swing kinematics and to evaluate how these effects differ as a function of expertise. The extraneous dual task degraded batting performance in novices but had no significant effect on experts. The skill-focused dual task increased batting errors and movement variability for experts but had no significant effect on novices. For expert batters, accuracy in the skill-focused dual task was inversely related to the current level of performance. Expert batters were significantly more accurate in the skill-focused dual task when placed under pressure. These findings indicate that the attentional focus varies substantially across and within performers with different levels of expertise.     

Lateralized interference effects: evidence for a processing style by modality interaction

A time-sharing paradigm was used to study potential interference effects of concurrent successive-auditory/vocal, successive-visual/motor, simultaneous-auditory/vocal, and simultaneous-visual/motor tasks on right- and left-handed manual-motor behaviors of differential levels of difficulty. Participants were selected from each of three developmental levels from 9 through 20 years of age. Results suggested that processing style (i.e., successive or simultaneous) interacts with modality (i.e., auditory/vocal or visual/motor) in terms of lateralized interference effects; however, potential effects due to age level were obfuscated by differential concurrent-task difficulties.     

Regarding time-sharing with convergent operations

This study contrasts the structural bottleneck and the resource view of attentional limits in time-sharing performance. The research incorporated features of the psychological refractory period (PRP) and the relative priority paradigm designed to maximize joint performance. A main distinction between the two attention views was their prediction on the extent that graded performance tradeoff was possible with graded priority changes. Detailed analysis of the performance and time-sharing strategies called into question the conclusions based exclusively on the PRP paradigm.     

Evidence against a short-term-store account of long-term recency effects

When subjects perform a distractor task before and after every item on a list, recall of the last itemis much higher than recall of items from the middle of the list. Koppenaal and Glanzer (1990) have shown that this long-term recency effect can be eliminated by using, after the last item, a distractor task different from that used elsewhere on the list. They interpreted this finding as evidence in favor of a short-term-store account of long-term recency effects. This account is challenged by the results reported here. Practice either on the task or on time-sharing between the task and list items had little impact on the recency effect. Also, substantial recency effects were found when a different distractor task occurred after every list position. Thus, it is not true that long-term recency effects are found only when subjects have an opportunity to adapt to the distractor task. Our results are not consistent with a short-term-store account of recency effects.     

Cognitive Structure,Content Knowledge,and Classificatory Reasoning

Classificatory reasoning was studied in 58 children, 7 and 8 years old, who differed in operational level as well as in expertise. Knowledge about dinosaurs was used to distinguish expertise level. The children's performance on class-inclusion tasks involving the dinosaur content was a function of operational level. An overall effect of expertise was found for children's performance on class-membership measures. Furthermore, on the class-membership measures, expertise did not significantly influence the performance of children at the concrete-operational level, but it did for children at the pre-operational level. The results suggest that domain-specific knowledge and operational level may have different but interacting influences on children's classificatory reasoning.     

Age and Assessments of Professional Expertise: The Relationship between Higher Level Employees’ Age and Self‐assessments or Supervisor Ratings of Professional Expertise

In this article the relationship between higher level employees’ age and assessments of professional expertise is described. Hypotheses have been tested with original survey data from 417 higher level employees and 224 direct supervisors. Concerning the analyses of the effects of age, our hypotheses have for the greater part been confirmed. In our study, we have found that age‐related stereotyping is an important phenomenon where assessments concerning professional expertise are made by supervisors. As regards the self‐ratings, there is no relationship between age and professional expertise. Further research is needed to understand the pattern of differences between the two types of ratings. Some speculations concerning improvements of the measurements are discussed.     

Effects of extensive dual-task practice on processing stages in simultaneous choice tasks

Schumacher et al. Psychological Science 12:101–108, (2001) demonstrated the elimination of most dual-task costs (“perfect time-sharing”) after extensive dual-task practice of a visual and an auditory task in combination. For the present research, we used a transfer methodology to examine this practice effect in more detail, asking what task-processing stages were sped up by this dual-task practice. Such research will be essential to specify mechanisms associated with the practice-related elimination of dual-task costs. In three experiments, we introduced postpractice transfer probes focusing on the perception, central response-selection, and final motor-response stages. The results indicated that the major change achieved by dual-task practice was a speed-up in the central response-selection stages of both tasks. Additionally, perceptual-stage shortening of the auditory task was found to contribute to the improvements in time-sharing. For a better understanding of such time-sharing, we discuss the contributions of the present findings in relation to models of practiced dual-task performance.     

When what you know is not enough: expertise and gender dynamics in task groups

This study investigates how the contribution, identification, and consideration of expertise within groups are affected by gender differences. The authors examined the effects of member expertise and gender on others' perceptions of expertise, actual and own perceptions of influence, and group performance on a decision-making task. The authors' findings are consistent with social role theory and expectation states theory. Women were less influential when they possessed expertise, and having expertise decreased how expert others perceived them to be. Conversely, having expertise was relatively positive for men. These differences were reflected in group performance, as groups with a female expert underperformed groups with a male expert. Thus, contrary to common expectations, possessing expertise did not ameliorate the gender effects often seen in workgroups. The findings are discussed in light of their implications for organizational workgroups in which contribution of expertise is critical to group performance.     

The effects of variability and expectations on utilization of member expertise and group performance

One of the most important resources a group has is the expertise of its members (Hackman & Morris, 1975; McGrath, 1984). Further, research suggests that recognition of expertise plays an important role in group performance (e.g., Libby, Trotman, & Zimmer, 1987). The current study experimentally manipulated member expectations and within-group variability and examined their relationships to recognition of expertise, utilization of expertise, and performance on a complex group decision-making task. Results indicate that variability and expectations affect utilization of expertise primarily through their effects on recognition of expertise. Recognition of expertise is positively associated with how often groups defer to their best member, but even when all members recognize the best member groups defer to that member only 62% of the time. Although reliance on the best member is positively related to group performance, the authors postulate that the relationship may be more complex than is commonly assumed.