Multitasking across the lifespan in different task contexts.

We assessed lifespan development of multitasking in a sample of 187 individuals aged 8-82 years. Participants performed a visuo-spatial working memory (VSWM) task together with either postural control or reaction time (RT) tasks. Using criterion-referenced testing we individually adjusted difficulty levels for the VSWM task to control for single-task differences. Age-differences in single-task performances followed U-shaped patterns with young adults outperforming children and older adults. Multitasking manipulations yielded robust performance decrements in VSWM, postural control and RT tasks. Presumably due to our adjustment of VSWM challenges, costs in this task were small and similar across age groups suggesting that age-differential costs found in earlier studies largely reflected differences already present during single-task performance. Age-differences in multitasking costs for concurrent tasks depended on specific combinations. For VSWM and RT task combinations increases in RT were the smallest for children but pronounced in adults highlighting the role of cognitive control processes. Stabilogram diffusion analysis of postural control demonstrated that long-term control mechanisms were affected by concurrent VSWM demands. This interference was pronounced in older adults supporting concepts of compensation or increased cognitive involvement in sensorimotor processes at older age. Our study demonstrates how a lifespan approach can delineate the explanatory scope of models of human multitasking.

Toward a Listening Training Paradigm: Evaluation in Normal-Hearing Young and Middle-Aged Adults.

OBJECTIVES: Adults' most common complaint relates to understanding speech in noisy environments. Hearing aids can compensate for sensory loss but do not restore hearing to normal. Listening training has the potential to partially remediate these problems. In this study, we propose and evaluate a Flemish version of a listening training paradigm, which involves the use of cognitive control as well as auditory perception. The paradigm entails a discrimination task where participants are cued to attend to one of two concurrent talkers with target speakers randomly varying between a female and a male voice. We evaluate learning effects, different scenarios, and masking types. DESIGN: In total, 70 young and 54 middle-aged adults participated in this study. Each adult performed one or more conditions. Participants' hearing was screened before participation, all middle-aged adults passed a cognitive screening task. RESULTS: Analyses indicated learning effects across scenarios that were similar in terms of speech intelligibility. Our results indicated better speech intelligibility when the female speaker was the target, but speech intelligibility did not differ when the target was the male speaker. An unintelligible masker noise results in worse speech intelligibility than a competing talker masker. Our results suggest that listeners could use an intensity cue to identify and/or select the target speaker when presented at a lower signal to noise ratio (SNR). Error analysis suggested higher cognitive control demands when the target and masker were presented at similar levels (i.e., around 0 dB SNR). The addition of independent trials with the intensity of target and masker reversed improved speech intelligibility. Inhibitory control, but not task switching, was reliably correlated with listening performance. CONCLUSIONS: The proposed paradigm turned out to be feasible and practicable, demonstrating its potential for training speech intelligibility in noise. We believe that this training paradigm can generate real-life benefits including for persons with hearing loss. This latter application awaits future evaluation.

Lifespan changes in postural control.

Lifespan development of postural control shows as an inverted U-shaped function with optimal performance in young adults and similar levels of underperformance in children and older adults. However, similarities in children and older adults might conceal differences in underlying control processes. We mapped out age-related differences in postural control using center-of-pressure trajectories of 299 participants ranging from 7 to 81 years old in three tasks: stable stance, compromised vision, and narrowed base of support. Summary statistics (path length, ellipse area) replicated the well-known U-shape function also showing that compromising vision and narrowing the base of support affected older adults more than children. Stabilogram diffusion analysis (SDA) allows to assess postural control performance in terms of diffusion at short (< 1 s) and longer timescales. SDA parameters showed the strongest short-term drift in older adults, especially under compromised vision or narrowed base of support conditions. However, older adults accommodated their poor short-term control by corrective adjustments as reflected in long-term diffusion under eyes closed conditions and initiating anti-persistent behavior earlier compared with children and young adults in tandem stance. We argue that these results highlight the adaptability of the postural control system and warrant a reinterpretation of previous postural control frameworks.

Perceptual grouping in complex rhythmic patterns.

Perception of simple temporal patterns has been shown to rely on accentuations in terms of intensity, pitch, or timbre, but also on grouping according to runs of the same events (intervals between successive sounds or light flashes) or significant gaps between them (Garner in The processing of information and structure. Lawrence Erlbaum, 1974; Preusser et al. in Am J Psychol 83(2):151-170 in 1970; Royer and Garner in Percept Psychophys 1(1):41-47, 1966; Royer and Garner in Percept Psychophys 7(2):115-120, 1970; Yu et al. in Atten Percept Psychophys 77(8):2728-2739, 2015). Here we investigate whether the run and gap principles can also account for participants' perceived start of complex rhythmic patterns. We also investigated the role of participants' musical training. Sixteen novices and 16 amateur musicians listened to rhythmic patterns and indicated perceived starting points by a single tap with a drumstick on electronic pads. Auditory patterns contained prominent gaps, runs, or a combination of the two for target intervals. We systematically varied task complexity in terms of the target durations of intervals constituting the patterns and overall tempos. Overall, run and gap principles proved to be useful grouping principles accounting for a large proportion (59.2%) of the selected starting positions underlining the universal relevance of these principles. Grouping principles were not as successful in predicting the perceived start of a rhythmic pattern compared to previous studies. Results indicate that additional grouping principles must be at play. Predictive power of the grouping principles varied depending on the structure of rhythmic patterns. For rhythmic patterns including longer intervals (i.e., longer gaps) the gap principle alone or in combination with the run principle showed the strongest predictive power. Novices and amateur musicians were similar in their usage of grouping principles suggesting that the underlying principles might be equally at the dispositions of performers and listeners.

Task-set control, chunking, and hierarchical timing in rhythm production.

We investigated task-set control processes and chunking in 16 novices and 16 amateur musicians, who produced unimanual rhythms in three experimental conditions: low-level timing tasks required isochronous tapping at constant target durations; sequencing tasks consisted of individual rhythmic patterns comprising multiple target durations; the task-set control condition required alternations between two rhythmic patterns. According to our hierarchical timing control model conditions differed in their task-set control demands necessary to provide rhythm programs for the sequencing of individual intervals. Transitions at predicted chunk boundaries were marked by increased frequencies of sequence errors, relative lengthening of intervals preceding the switch to a new rhythm chunk, and increased variabilities in intervals immediately following a switch. Amateur musicians showed superior timing (less variability) in complex rhythm tasks. Moreover, they made fewer sequence errors than novices at set-switch points with their error patterns suggesting that they relied on larger chunks compared with novices. Our findings elucidate the time course of task reconfiguration processes in rhythm production and the role of chunking in the context of musical skill.

Movement timing and cognitive control: adult-age differences in multi-tasking.

Over the course of six sessions, 24 young (M = 19.40 years, SD 1.61) and 24 older participants (M = 71.48 years, SD 3.86) performed simple, repetitive tapping tasks at 300 and 600 ms target durations concurrently with two cognitive tasks under non-switch or switch conditions. Despite substantial improvements, over sessions, reliable switch costs remained, which were pronounced in older adults. Young and older adults alike showed increased drift in the tapping tasks under dual-task conditions. Under dual-task non-switch conditions, older adults maintained the same timing accuracy (variability) as in the single-task condition. However, variability increased when concurrent cognitive task-set switching was required, while young adults even improved timing accuracy relative to the single-task condition. Being at odds with extant models of timing, our findings demonstrate that control of simple repetitive movements is far from automatic even at intervals below 1 s. Interference with timing in older adults is not caused by multi-tasking per se, but depends on the cognitive control demands of the concurrent task. We argue that our findings suggest a critical role of cognitive control processes for the maintenance of representations of target durations during interval production. This hypothesis received further support from patterns of local interference in the timing of individual intervals.

Leisure sports and postural control: can a black belt protect your balance from aging?

To determine potential benefits of intensive leisure sports for age-related changes in postural control, we tested 3 activity groups comprising 70 young (M = 21.67 years, SD = 2.80) and 73 older (M = 62.60 years, SD = 5.19) men. Activity groups were martial artists, who held at least 1st Dan (black belt), sportive individuals exercising sports without explicit balance components, and nonsportive controls. Martial artists had an advantage over sportive individuals in dynamic posture tasks (upright stance on a sway-referenced platform), and these 2 active groups showed better postural control than nonsportive participants. Age-related differences in postural control were larger in nonsportive men compared with the 2 active groups, who were similar in this respect. In contrast, negative age differences in other sensorimotor and cognitive functions did not differ between activity groups. We concluded that individuals engaging in intensive recreational sports have long-term advantages in postural control. However, even in older martial artists with years of practice in their sports, we observed considerable differences favoring the young.

Age-related differences in attentional cost associated with postural dual tasks: increased recruitment of generic cognitive resources in older adults.

Dual-task designs have been used widely to study the degree of automatic and controlled processing involved in postural stability of young and older adults. However, several unexplained discrepancies in the results weaken this literature. To resolve this problem, a careful selection of dual-task studies that met certain methodological criteria are considered with respect to reported interactions of age (young vs. older adults)×task (single vs. dual task) in stable and unstable postural conditions. Our review shows that older adults are able to perform a postural dual task as well as younger adults in stable conditions. However, when the complexity of the postural task is increased by dynamic conditions (surface and surround), performance in postural, concurrent, or both tasks is more affected in older relative to young adults. In light of neuroimaging studies and new conceptual frameworks, these results demonstrate an age-related increase of controlled processing of standing associated with greater intermittent adjustments.

The effects of aging on haptic 2D shape recognition.

We use the image-mediation model (Klatzky & Lederman, 1987) as a framework to investigate potential sources of adult age differences in the haptic recognition of two-dimensional (2D) shapes. This model states that the low-resolution, temporally sequential, haptic input is translated into a visual image, which is then reperceived through the visual processors, before it is matched against a long-term memory representation and named. In three experiments we tested groups of 12 older (mean age 73.11) and three groups of 12 young adults (mean age 22.80) each. In Experiment 1 we confirm age-related differences in haptic 2D shape recognition, and we show the typical age × complexity interaction. In Experiment 2 we show that if we facilitate the visual translation process, age differences become smaller, but only with simple shapes and not with the more complex everyday objects. In Experiment 3 we target the last step in the model (matching and naming) for complex stimuli. We found that age differences in exploration time were considerably reduced when this component process was facilitated by providing a category name. We conclude that the image-mediation model can explain adult-age differences in haptic recognition, particularly if the role of working memory in forming the transient visual image is considered. Our findings suggest that sensorimotor skills thought to rely on peripheral processes for the most part are critically constrained by age-related changes in central processing capacity in later adulthood.

The role of intuition and deliberative thinking in experts' superior tactical decision-making.

Current theories argue that human decision making is largely based on quick, automatic, and intuitive processes that are occasionally supplemented by slow controlled deliberation. Researchers, therefore, predominantly studied the heuristics of the automatic system in everyday decision making. Our study examines the role of slow deliberation for experts who exhibit superior decision-making outcomes in tactical chess problems with clear best moves. Our study uses advanced computer software to measure the objective value of actions preferred at the start versus the conclusion of decision making. It finds that both experts and less skilled individuals benefit significantly from extra deliberation regardless of whether the problem is easy or difficult. Our findings have important implications for the role of training for increasing decision making accuracy in many domains of expertise.

Dual task performance of working memory and postural control in major depressive disorder.

OBJECTIVE: Previous studies with patients diagnosed with Major Depressive Disorder (MDD) revealed deficits in working memory and executive functions. In the present study we investigated whether patients with MDD have the ability to allocate cognitive resources in dual task performance of a highly challenging cognitive task (working memory) and a task that is seemingly automatic in nature (postural control). METHOD: Fifteen young (18-35 years old) patients with MDD and 24 healthy age-matched controls performed a working memory task and two postural control tasks (standing on a stable or on a moving platform) both separately (single task) and concurrently (dual task). RESULTS: Postural stability under single task conditions was similar in the two groups, and in line with earlier studies, MDD patients recalled fewer working memory items than controls. To equate working memory challenges for patients and controls, task difficulty (number of items presented) in dual task was individually adjusted such that accuracy of working memory performance was similar for the two groups under single task conditions. Patients showed greater postural instability in dual task performance on the stable platform, and more importantly when posture task difficulty increased (moving platform) they showed deficits in both working memory accuracy and postural stability compared with healthy controls. CONCLUSIONS: We interpret our results as evidence for executive control deficits in MDD patients that affect their task coordination. In multitasking, these deficits affect not only cognitive but also sensorimotor task performance.

Long-term maintenance of retest learning in young old and oldest old adults.

This study examined the maintenance of retest learning benefits in young old and oldest old adults over an 8-month period in 3 cognitive abilities: reasoning, perceptual-motor speed, and visual attention. Twenty-four young old (aged 70-79 years, M = 74.2) and 23 oldest old adults (aged 80-90 years, M = 83.6) who participated in a previously published study (Yang, L., Krampe, R. T., & Baltes, P. B. [2006]. Basic forms of cognitive plasticity extended into the oldest-old: Retest learning, age, and cognitive functioning. Psychology and Aging, 21, 372-378) returned after an 8-month delay to complete 2 follow-up retest sessions. The results demonstrated that both young old and oldest old groups maintained about 50% of the original retest learning benefits. This extends the earlier findings of substantial long-term cognitive training maintenance in young old adults to a context of retest learning with oldest old adults, and thus portrays a positive message for cognitive plasticity of the oldest old.

Basic forms of cognitive plasticity extended into the oldest-old: retest learning, age, and cognitive functioning.

To address the question of whether cognitive plasticity varies by age and level of cognitive functioning in the older population, the authors used a self-guided retest paradigm to assess the basic forms of plasticity of 34 young-olds (M=74.4 years, range=70-79) and 34 oldest-olds (M=84.0 years, range=80-91), with half in each age group screened for high or low (midrange) level of cognitive functioning. As a whole, members of the sample represent about the upper two thirds of their age cohorts. Results show persistent, though age-reduced, learning in all samples and across all tests. However, age is not differentially "kinder" to the more able with respect to the age-graded decline in learning.

The effects of expertise and age on rhythm production: adaptations to timing and sequencing constraints.

We investigate age- and expertise-related individual differences in component processes of rhythmic timing. To this end we apply analysis of covariance structure and symbolic dynamics to time series obtained from performances of two bimanual rhythm tasks at different tempos. Results show similar effects for peripheral motor implementation and timekeeper execution in young and older amateur pianists. Older participants show specific problems with temporal sequencing processes (specification of different target intervals). Expert pianists show lower variability in both motor implementation and timekeeper execution and they accommodate to the sequencing demands of different tempos by selectively relying on integrated or parallel timing. We argue that the observed timing control characteristics reflect individuals' adaptations to internal processing limitations and performance constraints.