Ralf Krampe

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.

Sequential and Coordinative Processing Dynamics in Figural Transformations across the Life Span.

This work tests the proposition that two distinct factors involved in life span cognitive development are mental speed and coordination efficiency. Dynamics of information processing in a figural transformation task were assessed via time-accuracy functions for children (mean age = 9.5 years), young adults (mean age = 23.7 years), and old adults (mean age = 73.7 years). Corresponding to the two proposed factors, speed and coordination, both sequential and coordinative aspects of complexity were varied. Sequential complexity was manipulated through the number of objects to be checked for transformations; coordinative complexity was manipulated through the number of transformations to be considered simultaneously. Individual time--accuracy operating characteristics were adequately described by exponential functions for all age and complexity levels. Complexity-specific effects confirmed the general expectation of a particularly large age sensitivity of coordinative functions. Proportional adult age effects in the processing time parameter were larger for coordinatively complex than for sequentially complex conditions. For the contrast between children and young adults this was the case only for high coordinative complexity. Results are interpreted in terms of (a) dissociable developmental changes in speed of processing and working memory functioning across the life span and (b) differential effects of coordinative demands in children and old adults.

Task prioritization in aging: effects of sensory information on concurrent posture and memory performance

In older adults, cognitive resources play a key role in maintaining postural stability. In the present study, we evaluated whether increasing postural instability using sway referencing induces changes in resource allocation in dual-task performance leading older adults to prioritize the more age-salient posture task over a cognitive task. Young and older adults participated in the study which comprised two sessions. In the first session, three posture tasks (stable, sway reference visual, sway reference somatosensory) and a working memory task (n-back) were examined. In the second session, single- and dual-task performance of posture and memory were assessed. Postural stability improved with session. Participants were more unstable in the sway reference conditions, and pronounced age differences were observed in the somatosensory sway reference condition. In dual-task performance on the stable surface, older adults showed an almost 40% increase in instability compared to single-task. However, in the sway reference somatosensory condition, stability was the same in single- and dual-task performance, whereas pronounced (15%) costs emerged for cognition. These results show that during dual-tasking while standing on a stable surface, older adults have the flexibility to allow an increase in instability to accommodate cognitive task performance. However, when instability increases by means of compromising somatosensory information, levels of postural control are kept similar in single- and dual-task, by utilizing resources otherwise allocated to the cognitive task. This evidence emphasizes the flexible nature of resource allocation, developed over the life-span to compensate for age-related decline in sensorimotor and cognitive processing.

An Ecological Approach to Studying Aging and Dual-Task Performance.

An aspect of executive functioning observed to decline with normative and nonnormative aging is the control of attention when performing concurrent tasks. Previous research directed at localizing the underlying processes that might lead to such decline (e.g., reduced attentional capacity, attentional flexibility), has mostly used artificial laboratory tasks tapping into novel and unpracticed skills. Our approach emphasizes the ecological relevance of concurrent tasks for individuals of different age groups. In this context we highlight the interacting effects of specific losses in cognitive ability on the one hand, and compensatory resource allocation on the other. This perspective is informed by the Selection, Optimization, and Compensation (SOC) model of adaptive development advanced by Baltes and Baltes (1990), in which adaptation to losses can involve compensatory behaviors or a revision of goal or task priorities. After reviewing the basic literature on aging and cognitive dual-task performance, we discuss the case of dual-task cognitive and sensorimotor performance. There, studies show that healthy older adults selectively prioritize sensorimotor performance (walking, balance) over cognitive performance (memory encoding, response selection). This pattern appears to generalize to special populations of less cognitively intact older adults. Compensatory behavior focusing on the prioritized task provides further evidence of qualitatively different approaches to dual-task performance in older adults. The data reviewed prompt a reconsideration of our definitions of successful dual-task performance, and more generally, of intellectual status (intelligence) in old age. Aging and dual-task performance 3 “... cognitive aging researchers can accept the reality of declining cognitive powers stemming from the reduced efficiency of the brain but at the same time look for means by which older adults can best hold the negative effects of aging at bay and optimize the mental capacities they possess.” Salthouse & Craik (2002, p. 701) A pervasive challenge of modern adult life is to satisfy numerous demands within a constrained period of time. The simultaneous performance of two or more tasks such as driving and conversing (e.g., Strayer & Johnson, 2000), walking and talking (Kemper, Herman, & Lian, 2003), or listening while note-taking (Tun & Wingfield, 1995), constitutes a cognitive dual-task situation in which attention must be divided. Questionnaire data indicate that older adults rate the difficulty of everyday divided attention activities higher than do younger adults, whereas younger adults report a higher frequency of engaging in dual-task situations compared to older adults (Tun & Wingfield, 1995). The majority of age-comparative studies of divided attention performance concur with the subjective report data (for reviews, see Hartley, 1992; Kramer & Larish, 1996; McDowd, Vercruyssen, & Birren, 1991; McDowd & Shaw, 2000). The importance of dual-task functioning for independent living in old age, coupled with the general trend of age-related declines in such performance, has prompted a steady output of empirical work on this topic since the early 1960s (e.g., Broadbent & Heron, 1962). As with many other areas of cognitive aging research (Craik & Salthouse, 2000), substantial efforts have been devoted to understanding how and why age-related loss in dual-task performance is observed, but less work has been done to understand how such age deficits can be ameliorated (but see Kramer, Larish, & Strayer, 1995). Further, Aging and dual-task performance 4 little is known about the development of cognitive adaptations that may occur in midlife and beyond, in response to normative cognitive declines. Our approach to cognitive aging research (loss-plus-compensation) acknowledges both the reduction of efficiency and the compensatory means, as alluded to in our opening quotation. In this context we highlight the interacting effects of specific losses in cognitive ability on the one hand, and compensatory resource allocation on the other. This perspective is informed by the Selection, Optimization, and Compensation (SOC) model of adaptive development advanced by Baltes and Baltes (1990), in which adaptation to losses can involve compensatory behaviors or a revision of goal or task priorities. In this chapter, we first review central findings and theoretical models of aging and dual-task performance. We then discuss the importance of considering a more holistic or ecological approach to studying dual-task performance, illustrating with recent findings from the domain of concurrent cognitive and sensorimotor dual-task performance. Finally, we propose ways in which our loss-plus-compensation perspective might be applicable to models of individual and pathological differences in cognitive processing. There, we argue that taking a developmental approach to studying cognitive deficits associated with clinical conditions would help clarify debates concerning causality vis à vis symptomatology and cognitive status. What processing limitations are known? With few exceptions, investigations of aging and dual-task performance have been cross-sectional in design, with standard convenience samples of young adults in their 2 and 3 decades, and older adults in their 6 and 7 decades. The standard method of investigation involves measuring performance on each single task condition (Task A, Task B) and on the dual-task condition (Task A&B) to determine the degree to which Aging and dual-task performance 5 Task A and B performance decreases under dual-task conditions compared to their respective single-task baseline levels (dual-task costs; DTCs). Figure 1 illustrates the derivation of absolute and proportional dual-task costs. ----Insert Figure 1 about here ----Early empirical observations. Broadbent and Heron (1962) tested concurrent visual search of specified digits and auditory detection of repeated letters, finding age-related deficits in the auditory task but age-equivalence in the visual task. Talland (1962) reported a similar pattern using concurrent motor tasks (bead manipulation and rapid button pressing) such that older adults showed DTCs only on the second task, relative to young adults. Two subsequent studies juxtaposed simultaneous auditory and visual presentations of digits (McGhie, Chapman, & Lawson, 1965) or alternating digits and letters (Broadbent & Gregory, 1965). Both studies reported substantial age-related decreases in dual-task performance in both tasks. As noted by McDowd et al. (1991), older adults in these early studies appear to show some evidence of focusing on one task at the expense of the other. By modern standards, these studies lack the control of temporal parameters associated with some more recent work, allowing more opportunities for older adults to sequentialize or switch between tasks rather than concurrently perform both tasks. Processing resource explanations. Subsequent dual-task research focused more on specifying the processes responsible for age-related differences in dual-task performance. Wright’s (1981) investigation of concurrent digit span and verbal reasoning showed increasing age effects as a function of task complexity, which she attributed to decreasing general processing resources. Aging and dual-task performance 6 A more specific resource reduction approach has been taken by Salthouse and colleagues, who have argued that reductions in general processing speed result in lower dual-task performance because of the added processing stages required to carry out two tasks instead of one. Somberg and Salthouse (1982) prompted several important considerations by arguing that previous studies had not taken into account the age differences inherent under single-task conditions. In one experiment involving simultaneous visual target detection, they first calibrated single-task difficulty to ensure equivalent accuracy levels across individuals and age groups (Expt. 1). In a second experiment involving simultaneous tone detection and sequential digit keying, they computed relative, or proportional DTCs by computing the absolute difference in single versus dual-task performance, then dividing by single-task performance. Using these two methods of controlling for variations in single-task performance, Somberg and Salthouse reported age-invariance in DTCs. A subsequent study (Salthouse, Rogan, & Prill, 1984) produced an important caveat: Using more complex tasks than before, Salthouse et al. (1984) reported greater DTCs in older than younger participants, even when task difficulty was individually calibrated. As well, with these more controlled stimuli, Salthouse and colleagues demonstrated that young and older adults were similar in their ability to shift their attentional emphasis across tasks when instructed to by using proportions or ratios as goals (e.g., 25:75, 50:50, 75:25; see also Crossley & Hiscock, 1992). Salthouse’s early dual-task findings provoked a more direct examination of the effects of task complexity (McDowd & Craik, 1988). Using auditory 2-choice reaction time (RT) and visual 4-choice RT tasks, McDowd and Craik manipulated the depth of processing (perceptual or semantic) required to make the decisions in each task (Expt. Aging and dual-task performance 7 1). These increases in complexity had interacting effects with age when calculated as absolute, but not relative, DTCs (see also Baron & Mattila, 1989). In a second experiment using different visual and auditory tasks, they found that manipulations of difficulty had comparable effects on young and older adults. Taken together, these experiments yield mixed support for the complexity hypothesis, although they demonstrate a clear age-related decline in dual-task performance. Lorsbach and Simpson (1988) also introduced a manipulation of complexity by varying depth of processing. Participants made same-different judgments to letter pairs o

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.

Timing, sequencing, and executive control in repetitive movement production.

The authors demonstrate that the timing and sequencing of target durations require low-level timing and executive control. Sixteen young (M-sub(age) = 19 years) and 16 older (M-sub(age) = 70 years) adults participated in 2 experiments. In Experiment 1, individual mean-variance functions for low-level timing (isochronous tapping) and the sequencing of multiple targets (rhythm production) revealed (a) a dissociation of low-level timing and sequencing in both age groups, (b) negligible age differences for low-level timing, and (c) large age differences for sequencing. Experiment 2 supported the distinction between low-level timing and executive functions: Selection against a dominant rhythm and switching between rhythms impaired performances in both age groups and induced pronounced perseveration of the dominant pattern in older adults.

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.

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.

Perceptual Grouping in Haptic Search: The Influence of Proximity, Similarity, and Good Continuation

We conducted a haptic search experiment to investigate the influence of the Gestalt principles of proximity, similarity, and good continuation. We expected faster search when the distractors could be grouped. We chose edges at different orientations as stimuli because they are processed similarly in the haptic and visual modality. We therefore expected the principles of similarity and good continuation to be operational in haptics as they are in vision. In contrast, because of differences in spatial processing between vision and haptics, we expected differences for the principle of proximity. In haptics, the Gestalt principle of proximity could operate at two distinct levels-somatotopic proximity or spatial proximity-and we assessed both possibilities in our experiments. The results show that the principles of similarity and good continuation indeed operate in this haptic search task. Neither of our proximity manipulations yielded effects, which may suggest that grouping by proximity must take place before an invariant representation of the object has formed. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

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.