Dual-task costs of texting while walking forward and backward are greater for older adults than younger adults

Cognitive-motor dual-tasking involves concurrent performance of two tasks with distinct cognitive and motor demands and is associated with increased fall risk. In this hypothesis-driven study, younger (18–30 years, n = 24) and older (60–75 years, n = 26) adults completed six walking tasks in triplicate. Participants walked forward and backward along a GAITRite mat, in isolation or while performing a verbal fluency task. Verbal fluency tasks involved verbally listing or typing on a smartphone as many words as possible within a given category (e.g., clothes). Using repeated measures MANOVA models, we examined how age, method of fluency task (verbal or texting), and direction of walking altered dual-task performance. Given that tasks like texting and backward walking require greater cognitive resources than verbal and forward walking tasks, respectively, we hypothesized older adults would show higher dual-task costs (DTCs) than younger adults across different task types and walking directions, with degree of impairment more apparent in texting dual-task trials compared to verbal dual-task trials. We also hypothesized that both age groups would have greater DTCs while walking backward than while walking forward, regardless of task.Independent of age group, velocity and stride length were reduced for texting compared to the verbal task during both forward and backward walking; cadence and velocity were reduced while walking forward compared to walking backward for the texting task; and stride length was reduced for forward walking compared to backward walking during the verbal task. Younger adults performed better than older adults on all tasks with the most pronounced differences seen in velocity and stride length during forward-texting and backward-texting. Interaction effects for velocity and stride length while walking forward indicated younger adults performed better than older adults for the texting task but similarly during the verbal task. An interaction for cadence during the verbal task indicated younger adults performed better than older adults while walking backward but similarly while walking forward.In summary, older adults experienced greater gait decrement for all dual-task conditions. The greater declines in velocity and stride length in combination with cadence being stable suggest reductions in velocity during texting were due to shorter strides rather than a reduced rate of stepping. Contrary to our hypotheses, we found greater DTCs while walking forward rather than backward, which may be due to reduced gait performance during single-task backward walking; thus, further decrements with dual-tasking are unlikely. These findings underscore the need for further research investigating fall risk potential associated with texting and walking among aging populations and how interventions targeting stride length during dual-task circumstances may improve performance.     

Aging ebbs the flow of thought: Adult age differences in mind wandering,executive control,and self-evaluation

Two experiments examined the relations among adult aging, mind wandering, and executive-task performance, following from surprising laboratory findings that older adults report fewer task-unrelated thoughts (TUTs) than do younger adults (e.g., Giambra, 1989, Jackson and Balota, 2012). Because older adults may experience more ability- and performance-related worry during cognitive tasks in the laboratory, and because these evaluative thoughts (known as task-related interference, “TRI”) might be sometimes misclassified by subjects as task-related, we asked subjects to distinguish task-related thoughts from TRI and TUTs when probed during ongoing tasks. In Experiment 1, younger and older adults completed either a go/no-go or a vigilance version of a sustained attention to response task (SART). Older adults reported more TRI and fewer TUTs than did younger adults while also performing more accurately. In Experiment 2, subjects completed either a 1- or a 2-back version of the n-back task. Older adults again reported more TRI and fewer TUTs than younger adults in both versions, while performing better than younger adults in the 1-back and worse in the 2-back. Across experiments, older adults' reduced TUT rates were independent of performance relative to younger adults. And, although older adults consistently reported more TRI and less mind wandering than did younger adults, overall they reported more on-task thoughts. TRI cannot, therefore, account completely for prior reports of decreasing TUTs with aging. We discuss the implications of these results for various theoretical approaches to mind-wandering.     

Trait anxiety,visuospatial processing,and working memory

This experiment assessed the components of Baddeley's working memory system impaired by anxiety during performance of the Corsi Blocks Test. The Corsi task was performed concurrently with different secondary tasks (i.e., articulatory suppression; counting backwards; spatial tapping; simple tapping). Results showed Corsi performance depended mainly on the central executive and visuospatial sketchpad components of working memory. Adverse effects of trait anxiety on the Corsi task were observed on the central executive but not on the phonological loop or the visuospatial sketchpad. These effects were not mediated by state anxiety. The findings indicate for the first time that trait anxiety impairs central executive functioning on a nonverbal task, and that anxiety does not impair functioning of the “slave” systems (i.e., phonological loop; visuospatial sketchpad). Theoretical implications of these findings are discussed.     

Does a simultaneous memory load affect older and younger adults’ implicit associative learning?

This study investigated the effects of a simultaneous memory load on implicit associative sequence learning using the Triplets Learning Task (TLT). Participants in the Simultaneous condition held a secondary task memory load during the TLT, while those in the Sequential condition also performed both tasks, but successively, rather than simultaneously. Thus, the Simultaneous condition had a memory load during the TLT, while the Sequential condition did not. Probe blocks without the secondary task allowed separation of effects on learning from effects on its expression. Results revealed that the simultaneous memory load affected older, but not younger adults, by suppressing the expression of learning, not learning itself. Thus, older and younger adults can learn probabilistic associations while holding a simultaneous memory load, but the load can limit the extent to which older adults adapt their performance to environmental structure. Results are consistent with theories which propose that implicit associative learning does not call on limited capacity resources, and highlight the importance of distinguishing effects of dual tasks on the expression of learning from those on learning itself.     

Age- and practice-related influences on dual-task costs and compensation mechanisms under optimal conditions of dual-task performance

Impaired dual-task performance in younger and older adults can be improved with practice. Optimal conditions even allow for a (near) elimination of this impairment in younger adults. However, practice effects under these conditions in older adults are unknown. Further, it is open, how changed task scheduling and/ or the acquisition of task coordination skills affect the temporal overlap of two tasks in different age groups; this overlap indicate the involvement of these practice-related mechanisms to compensate for impaired dual-task performance. In a dual-task situation of Schumacher et al. (2001 , Psychological Science, 12, 230) including optimal conditions for dual-task performance, both younger and older adults were able to achieve an improvement in dual-task performance with 8 practice sessions to the same degree. The temporal task overlap changed similarly in both age groups during these sessions demonstrating a similar degree of the involvement of compensation mechanisms in younger and older adults. At the end of practice, however, we showed that older adults do not achieve the same optimized dual-task performance level of younger adults.     

Age,working memory,and the Tower of London task

The current study explores the role of three components of working memory in age differences in an executive task, the Tower of London (TOL). The TOL task is sensitive to frontal lobe damage, and is widely used to measure planning ability. Dual tasks were used to test the involvement of the phonological loop (articulatory suppression), visuospatial buffer (pattern tapping), and central executive (random generation) in age effects on the TOL. Older adults showed greater reliance than young on domain-specific verbal and spatial memory components in performing the TOL. In terms of executive function, qualitatively different interference patterns were seen in young and old participants. However, the validity of using random generation tasks to assess executive function in older populations can be questioned. For older participants, performing the TOL loads all components of working memory, whereas for the younger participants the TOL more specifically loads executive functioning.     

Sequential tapping interferes selectively with multiple-object tracking: Do finger-tapping and tracking share a common resource?

Multiple-object tracking involves simultaneously monitoring positions of a number of target items as they move among distractors. Young adults are capable of tracking only 3–5 items at once. In this study we investigated the origin of this limitation by looking for secondary tasks that interfere with tracking. We compared tracking performance (baseline condition), with performance when participants tapped three fingers in a specific order while tracking (sequential tapping) or articulated three syllables in a specific order while tracking (sequential articulation). The articulation task was used to ensure that the interference produced by sequential tapping was more than would be expected by the executive demands of carrying out any two “attention-demanding” tasks at once. Even though sequential tapping does not require vision or memorizing the positions of external items, it produced significantly more interference than did sequential articulation, as might be expected if tracking and sequential tapping shared a common (limited) resource.     

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.     

Sequential tapping interferes selectively with multiple-object tracking: do finger-tapping and tracking share a common resource?

Multiple-object tracking involves simultaneously monitoring positions of a number of target items as they move among distractors. Young adults are capable of tracking only 3-5 items at once. In this study we investigated the origin of this limitation by looking for secondary tasks that interfere with tracking. We compared tracking performance (baseline condition), with performance when participants tapped three fingers in a specific order while tracking (sequential tapping) or articulated three syllables in a specific order while tracking (sequential articulation). The articulation task was used to ensure that the interference produced by sequential tapping was more than would be expected by the executive demands of carrying out any two “attention-demanding” tasks at once. Even though sequential tapping does not require vision or memorizing the positions of external items, it produced significantly more interference than did sequential articulation, as might be expected if tracking and sequential tapping shared a common (limited) resource.     

Age, Focal Processing, and Monitoring in Event-Based Prospective Memory

While there is some consensus that prospective memory (PM) declines with age, the reasons for differences in performance across age groups are not fully understood. This experiment examines two factors that are likely to affect the magnitude of observed age group differences: type of PM task and whether participants monitor the task environment for the opportunity to complete the PM task. Younger and older adults were engaged in an ongoing test of short-term memory and were asked to perform one of two different event-based PM tasks. Younger adults performed better than older adults on both focal and nonfocal PM tasks. In addition, younger adults were able to perform both types of tasks equally well, but older adults were more successful on the focal task than on the nonfocal task. Age group differences in self-reported PM monitoring were also evident and were related to performance. These findings and their implications for current theoretical conceptions of PM aging are discussed.     

Different effects of dual task demands on the speech of young and older adults

Young and older adults provided language samples in response to elicitation questions while concurrently performing 3 different tasks. The language samples were scored on three dimensions: fluency, grammatical complexity, and content. Previous research had suggested the hypothesis that the restricted speech register of older adults is buffered from the costs of dual task demands. This hypothesis was tested by comparing language samples collected during a baseline condition with those produced while the participants were performing the concurrent tasks. The results indicate that young and older adults adopt different strategies when confronted with dual task demands. Young adults shift to a restricted speech register when confronted with dual task demands. Older adults, who were already using a restricted speech register, became less fluent although the grammatical complexity and informational content of their speech was preserved. Hence, some but not all aspects of older adults' speech are buffered from dual task demands.     

Implicit Learning of Affective Responses in Dementia Patients: A Face-Emotion-Association Paradigm

ABSTRACT

Young and older adults performed verbal and spatial storage-only and storage-plus-processing working memory tasks while performing a secondary finger tapping task, and the effects on both the maximum capacity (measured as the longest series correct) and the reliability (measured as the proportion of items correct) of working memory were assessed. Tapping tended to produce greater disruption of working memory tasks that place greater demands on executive processes (i.e., storage-plus-processing tasks compared to storage-only span tasks). Moreover, tapping produced domain-general interference, disrupting both verbal and spatial working memory, providing further support for the idea that tapping interferes with the executive component of the working memory system, rather than domain-specific maintenance processes. Nevertheless, tapping generally produced equivalent interference effects in young and older adults. Taken together, these findings are inconsistent with the hypothesis that age-related declines in working memory are primarily attributable to a deficit in the executive component.     

Older adults exhibit altered motor coordination during an upper limb object transport task requiring a lateral change in support

Investigating an ecologically relevant upper limb task, such as manually transporting an object with a concurrent lateral change in support (sidestepping alongside a kitchen counter), may provide greater insight into potential deficits in postural stability, variability and motor coordination in older adults. Nine healthy young and eleven older, community dwelling adults executed an upper limb object transport task requiring a lateral change in support in two directions at two self-selected speeds, self-paced and fast-paced. Dynamic postural stability and movement variability was quantified via whole-body center of mass motion. The onset of lead lower limb movement in relation to object movement onset was quantified as a measure of motor coordination. Older adults demonstrated similar levels of stability and variability as their younger counterparts, but at slower peak movement velocity and increased task duration. Furthermore, older adults demonstrated asymmetrical motor coordination between left and right task directions, while younger adults remained consistent regardless of task direction. Thus, older adults significantly modulated movement speed and motor coordination to maintain similar levels of stability and variability compared to their younger counterparts.     

The transient nature of executive control processes in younger and older adults

In this paper I review data from recent studies supporting the hypothesis that executive control processes fluctuate in efficiency over time and that these fluctuations are more pervasive in older than younger adults. Patterns of response accuracy in tasks requiring selective attention and prospective memory reveal that lapses of intention are often preceded and followed by periods of goal-directed action. Analysis of response time distributions reveals that increased performance variability in older adults for task conditions requiring executive control results from an increase in the degree of positive skewing of the distribution. Together, these findings lead to the suggestion that disruptions of executive control processes supporting performance in demanding tasks are temporally limited in nature. Data from recent neurophysiological studies indicates a possible role of the prefrontal cortex in maintaining optimal levels of executive control.     

The attentional demands of encoding and retrieval in younger and older adults: 2. Evidence from secondary task reaction time distributions

Three studies examined the effects of encoding or retrieval on properties of secondary task reaction time (RT) distributions in younger and older adults. Relative to full attention conditions, encoding and retrieval increased secondary task RT medians and standard deviations more for older adults than for younger adults, and the age-related RT increase was most pronounced among the slowest RTs. Hierarchical regression analyses revealed two age-related mechanisms underlying these effects, which were interpreted as cognitive slowing and reductions in attentional resources. Cognitive slowing affects the entire RT distribution regardless of the memory task. By contrast, reduced attentional resources result in very long RTs, especially when the tasks require self-initiated encoding or retrieval operations.     

Age-related differences in working memory and force control under dual-task conditions

The aim of this study was to investigate the relationship between force control and cognitive performance under dual-task conditions in younger (18-22 years) and older adults (65-77 years). Cognitive (n-back test) and motor performance (force-tracking) was measured independently and simultaneously. Results indicated overall age-related differences for the n-back and the force-tracking task. Age-related differences increased during dual-task conditions. While younger adults exhibited no decrease in cognitive or motor performance during dual-task conditions, older adults showed a decrease in motor and cognitive performance. Additionally, when older adults made an error in the cognitive task they tended to show greater variability in the force-tracking task. These results suggest that cognitive motor deficits are responsible for older adults' performance decrements under dual-task conditions.     

Age-differential motivational consequences of optimization versus compensation focus in younger and older adults

Four studies investigated age-related differences in goal focus in younger and older adults. Studies 1 and 2 confirmed the hypothesis that younger adults are more persistent when the same sensorimotor task offers possibility for optimizing performance than when the task requires counteracting a loss in performance (compensation). In contrast, older adults were more persistent in the compensation than in the optimization condition. Study 3 showed that the age-differential effects of goal focus on persistence were not simply due to perceiving the 2 conditions as easy versus difficult. Study 4 ruled out that the age differences were due to differences in the 2 tasks themselves. Taken together, the studies underscore the importance of situating motivational research into a life span context.     

Age differences in response selection for pure and mixed stimulus-response mappings and tasks

Two experiments examined effects of mixed stimulus-response mappings and tasks for older and younger adults. In Experiment 1, participants performed two-choice spatial reaction tasks with blocks of pure and mixed compatible and incompatible mappings. In Experiment 2, a compatible or incompatible mapping was mixed with a Simon task for which the mapping of stimulus color to location was relevant and stimulus location was irrelevant. In both experiments, older adults showed larger mixing costs than younger adults and larger compatibility effects, with the differences particularly pronounced in Experiment 1 when location mappings were mixed. In mixed conditions, when stimulus location was relevant, older adults benefited more than younger adults from complete repetition of the task and stimulus from the preceding trial. When stimulus location was irrelevant, the benefit of complete repetition did not differ reliably between age groups. The results suggest that the age-related deficit associated with mixing mappings and tasks is primarily due to older adults having more difficulty separating task sets that activate conflicting response codes.     

Different Effects of Dual Task Demands on the Speech of Young and Older Adults

Abstract

Young and older adults provided language samples in response to elicitation questions while concurrently performing 3 different tasks. The language samples were scored on three dimensions: fluency, grammatical complexity, and content. Previous research has shown that older adults use a restricted speech register that is grammatically less complex than young adults’ and has suggested that this restricted speech register is buffered from the costs of dual task demands. This hypothesis was tested by comparing language samples collected during a baseline condition with those produced while the participants were performing the concurrent tasks. The results indicate that young and older adults adopt different strategies when confronted with dual task demands. Young adults shift to a restricted speech register when confronted with dual task demands. Older adults, who were already using a restricted speech register, became less fluent although the grammatical complexity and informational content of their speech was preserved. Hence, some but not all aspects of older adults’ speech are buffered from dual task demands.