Dual-task Setting Research Articles

Simultaneous EEG recording of cortical tracking of speech and movement kinematics

Rationale: Cortical activity is coupled with streams of sensory stimulation. The coupling with the temporal envelope of heard speech is known as the cortical tracking of speech (CTS), and that with movement kinematics is known as the corticokinematic coupling (CKC). Simultaneous measurement of both couplings is desirable in clinical settings, but it is unknown whether the inherent dual-tasking condition has an impact on CTS or CKC. AimWe aim to determine whether and how CTS and CKC levels are affected when recorded simultaneously. MethodsTwenty-three healthy young adults underwent 64-channel EEG recordings while listening to stories and while performing repetitive finger-tapping movements in 3 conditions: separately (audio- or tapping-only) or simultaneously (audio-tapping). CTS and CKC values were estimated using coherence analysis between each EEG signal and speech temporal envelope (CTS) or finger acceleration (CKC). CTS was also estimated as the reconstruction accuracy of a decoding model. ResultsAcross recordings, CTS assessed with reconstruction accuracy was significant in 85 % of the subjects at phrasal frequency (0.5 Hz) and in 68 % at syllabic frequencies (4–8 Hz), and CKC was significant in over 85 % of the subjects at movement frequency and its first harmonic. Comparing CTS and CKC values evaluated in separate recordings to those in simultaneous recordings revealed no significant difference and moderate-to-high levels of correlation.Conclusion.Despite the subtle behavioral effects, CTS and CKC are not evidently altered by the dual-task setting inherent to recording them simultaneously and can be evaluated simultaneously using EEG in clinical settings.

Visual and Haptic Guidance for Enhancing Target Search Performance in Dual-Task Settings

In complex environments, users frequently need to manage multiple tasks simultaneously, which poses significant challenges for user interface design. For instance, when driving, users must maintain continuous visual attention on the road ahead while also monitoring rearview mirrors and performing shoulder checks. These multitasking scenarios present substantial design challenges in effectively guiding users. To address these challenges, we focus on investigating and designing visual and haptic guidance systems to augment users’ performance. We initially propose the use of visual guidance, specifically employing a dynamic arrow as a guidance technique. Our evaluation shows that dynamic arrows significantly expedite both reaction and selection times. We further introduce and evaluate haptic feedback, which users perceive as more salient than visual guidance, leading to quicker responses when switching from primary to secondary tasks. This allows users to maintain visual attention on the primary task while simultaneously responding effectively to haptic cues. Our findings suggest that multimodal guidance, especially haptic guidance, can enhance both reaction time and user experience in dual-task environments, offering promising practical implications and guidelines for designing more user-friendly interfaces and systems.

The interference of negative emotional stimuli on semantic vigilance performance in a dual-task setting

A large body of previous research has shown that emotional stimuli have an advantage in a wide variety of cognitive processes. This was mainly observed in visual search and working memory tasks. Emotionally charged objects draw and hold attention, are remembered better, and interfere more with the completion of the primary task than neutral ones. Therefore, it seems reasonable to assume that emotional stimuli also greatly affect sustained attention and vigilance decrement. In the present research, we investigated whether emotional stimuli demand more attentional resources than neutral ones in a dual-task paradigm. We adopted the abbreviated semantic discrimination vigilance task and measured participants’ (N = 49) performance in a single-task and two dual-task settings. In the dual-task conditions, the visual semantic vigilance paradigm was combined with an auditory word recall task (with neutral or emotional stimuli). We found reduced vigilance and improved word recall performance in the emotional dual-task condition compared to the neutral dual-task and single-task conditions. The reduced performance was apparent throughout the task, while in the neutral conditions, participants’ performance first increased and then dropped as time progressed. To conclude, our results indicate that emotional stimuli not only have an advantage in cognitive processing but also demand more attentional resources continuously while it is present compared to neutral stimuli. These results are consistent with the emotionality effect theory and evolutionary accounts of the neural circuits underlying motivated behaviors associated with critical survival needs.

Effect of dual-task interaction combining postural and visual perturbations on cortical activity and postural control ability

Previous studies have suggested cortical involvement in postural control in humans by measuring cortical activities and conducting dual-task paradigms. In dual-task paradigms, task performance deteriorates and can be facilitated in specific dual-task settings. Theoretical frameworks explaining these dual-task interactions have been proposed and debated for decades. Therefore, we investigated postural control performance under different visual conditions using a virtual reality system, simultaneously measuring cortical activities with a functional near-infrared spectroscopy system. Twenty-four healthy participants were included in this study. Postural stability and cortical activities after perturbations were measured under several conditions consisting of postural and visual perturbations. The results showed that concurrent visual and postural perturbations could facilitate cortical activities in the supplementary motor area and superior parietal lobe. Additionally, visual distractors deteriorated postural control ability and cortical activation of the supplementary motor area. These findings supported the theoretical framework of the “Cross talk model”, in which concurrent tasks using similar neural domains can facilitate these task performances. Furthermore, it indicated that the cortical resource capacity and domains activated for information processing should be considered in experiments involving dual-task paradigms and training.

Multifractal Nonlinearity Moderates Feedforward and Feedback Responses to Suprapostural Perturbations.

An adaptive response to unexpected perturbations requires near-term and long-term adjustments over time. We used multifractal analysis to test how nonlinear interactions across timescales might support an adaptive response following an unpredictable perturbation. We reanalyzed torque data from 44 young and 24 older adults who performed a single-leg squat task challenged by an unexpected mechanical perturbation and a secondary visual-cognitive task. We report three findings: (a) multifractal nonlinearity interacted with pre-perturbation torque production and task error to presage greater pre-voluntary feedforward increases and greater voluntary reductions, respectively, in post-perturbation task error; (b) multifractal nonlinearity presaged relatively smaller task error than standard deviations of both pre-perturbation torques and pre-perturbation task error; and (c) increased task demand (e.g., age-related changes in dexterity and dual-task settings) led to multifractal nonlinearity presaging reduced task error. All these results were consistent with our expectations, except that a pre-perturbation knee torque-dependent increase in post-perturbation task error appeared later for older than for younger participants. This correlational multifractal modeling offered theoretical clarity on the possible roles of nonlinear interactions across timescales, moderating both feedforward and feedback processes, and presaging greater stability when the standard deviation is relatively large and task demands are strong. Thus, multifractal nonlinearity usefully describes movement variability even when paired with classical descriptors like the standard deviation. We discuss potential insights from these findings for understanding suprapostural dexterity and developing rehabilitative interventions.

Divided Attention Alters Trailing Limb Stepping activity– A Dual-task Study

<h3>Research Objectives</h3> To investigate the changes of lower extremity joint kinematics and gait characteristics of the trailing leg during the dual-task obstacle crossing task (OCT). <h3>Design</h3> Observational study from a healthy cohort. <h3>Setting</h3> Hospital and research institute setting. <h3>Participants</h3> Nine young healthy participants (4 females and 5 males; age:27.8±4.1 years old) were recruited from University of Kansas Medical Center following the volunteer sample selection procedure. Key eligibility criteria included: (1) be able to independently walk for 30 minutes; (2) no neurological disorders that cause postural instability; (3) no recent (< 6 months) lower extremity fracture. <h3>Interventions</h3> Participants were instructed to walk on the instrumented C-Mill VR treadmill (Motek, the Netherlands) and step over obstacle images projected on the treadmill belt using right legs as leading legs. During the dual-task OCT, an auditory Stroop test was administered concurrently. Eight-sensor APDM Moveo Explorer system (Portland, OR) was used to collect the trailing leg's joint kinematics and spatiotemporal gait characteristics. <h3>Main Outcome Measures</h3> The trailing leg's joint angles and spatiotemporal characteristics while stepping over the obstacle in a single- and dual- task condition were measured. We hypothesized that both joint angles and characteristics would be significantly altered in the dual-task setting. <h3>Results</h3> The maximal knee extension was significantly decreased. The double-support time was significantly extended while the stride length was significantly decreased. There has a trending that the height of foot elevation at mid-swing phase of stepping was decreased (ρ = 0.07). <h3>Conclusions</h3> Our hypothesis was supported through the decreased knee extension, stride length and increased double-support time. Future studies are warranted to identify trailing leg's stepping strategies among aging or neurodegenerative populations. <h3>Author(s) Disclosures</h3> No conflict of interests was disclosed in this study.

Abnormal neural oscillations during gait and dual-task in Parkinson's disease.

Gait dysfunctions are debilitating motor symptoms of Parkinson’s disease (PD) and may result in frequent falling with health complications. The contribution of the motor-cognitive network to gait disturbance can be studied more thoroughly by challenging motor-cognitive dual-task gait performances. Gait is a complex motor task that requires an appropriate contribution from motor and cognitive networks, reflected in frequency modulations among several cortical and subcortical networks. Electrophysiological recordings by scalp electroencephalography and implanted deep brain stimulation (DBS) electrodes have unveiled modulations of specific oscillatory patterns in the cortical-subcortical circuits in PD. In this review, we summarize oscillatory contributions of the cortical, basal ganglia, mesencephalic locomotor, and cerebellar regions during gait and dual-task activities in PD. We detail the involvement of the cognitive network in dual-task settings and compare how abnormal oscillations in the specific frequency bands in the cortical and subcortical regions correlate with gait deficits in PD, particularly freezing of gait (FOG). We suggest that altered neural oscillations in different frequencies can cause derangements in broader brain networks, so neuromodulation and pharmacological therapies should be considered to normalize those network oscillations to improve challenged gait and dual-task motor functions in PD. Specifically, the theta and beta bands in premotor cortical areas, subthalamic nucleus, as well as alpha band activity in the brainstem prepontine nucleus, modulate under clinically effective levodopa and DBS therapies, improving gait and dual-task performance in PD with FOG, compared to PD without FOG and age-matched healthy control groups.

Inconsistent attentional contexts impair relearning following gradual visuomotor adaptation.

One of the brain's primary functions is to promote actions in dynamic, distracting environments. Because distractions divert attention from our primary goals, we must learn to maintain accurate actions under sensory and cognitive distractions. Visuomotor adaptation is a learning process that restores performance when sensorimotor capacities or environmental conditions are abruptly or gradually altered. Prior work showed that learning to counteract an abrupt perturbation under a particular single- or dual-task setting (i.e., attentional context) was associated with better recall under the same conditions. This suggested that the attentional context was encoded during adaptation and used as a recall cue. The current study investigated whether the attentional context (i.e., single vs. dual task) also affected adaptation and recall to a gradual perturbation, which limited awareness of movement errors. During adaptation, participants moved a cursor to a target while learning to counteract a visuomotor rotation that increased from 0° to 45° by 0.3° each trial, with or without performing a secondary task. Relearning was impaired when the attentional context was different between adaptation and recall (experiment 1), even when the exposure to the attentional context was limited to the early or late half of adaptation (experiment 2). Changing the secondary task did not affect relearning, indicating that the attentional context, rather than specific stimuli or tasks, was associated with better recall performance (experiment 3). These findings highlight the importance of cognitive factors, such as attention, in visuomotor adaptation and have implications for learning and rehabilitation paradigms.NEW & NOTEWORTHY Adaptation acquired under single- or dual-task setting, which created an undivided or divided attentional context, respectively, was impaired when relearning occurred under different conditions (i.e., shifting from a dual to single task). Changes to the attentional context impaired relearning when the initial adaptation was to a gradual perturbation. Explicit awareness of the perturbation was not necessary for this effect to be robust, nor was the effect attributable to changes in the secondary task requirements.

Imposed load versus voluntary investment: Executive control and attention management in dual-task performance

Dual task performance is one of the most frequently used paradigm in the evaluation of coping with concurrent task demands. The Breakfast Task experimented in this paper, was originally developed as a general indicator of coping ability with high demand executive control and attention management requirements. It is a computer-based simulation, in which the performer is required to cook several food items while concurrently setting table for guests.The task was employed in different studies, to compare young to old adults, monolinguals to bilinguals, influence of Parkinson disease and brain injury. However, in a closer examination, it is a dual task setting, in which cooking reflects coping with imposed load while table setting is an indicator of strategy free, voluntary invested effort. Models of workload did not examine the impact of such asymmetric flexibility on concurrent performance. Three experiments with elaborated versions of the breakfast task, show that the difference between the tasks affects concurrent performance formats in response to manipulations of task difficulty, priority change and practice. These results and their implications are discussed in reference to limited capacity, resource and executive control models of multitasking and task load.

Muscle activity in explicit and implicit sequence learning: Exploring additional measures of learning and certainty via tensor decomposition

Sequence learning in serial reaction time tasks (SRTTs) is usually inferred through the reaction time measured by a keyboard. However, this chronometric parameter offers no information beyond the time point of the button-press. We therefore examined whether sequence learning can be measured by muscle activations via electromyography (EMG) in a dual-task paradigm. The primary task was a SRTT, in which the stimuli followed a fixed sequence in some blocks, whereas the sequence was random in the control condition. The secondary task stimulus was always random. One group was informed about the fixed sequence, and the other not. We assessed three dependent variables. The chronometric parameter premotor time represents the duration between stimulus onset and the onset of EMG activity, which indicates the start of the response. The other variables describe the response itself considering the EMG activity after response start. The EMG integral was analyzed, and additionally, tensor decomposition was implemented to assess sequence dependent changes in the contribution of the obtained subcomponents. The results show explicit sequence learning in this dual-task setting. Specifically, the informed group show shorter premotor times in fixed than random sequences as well as larger EMG integral and tensor contributions. Further, increased activity seems to represent response certainty, since a decrease is found for both groups in trials following erroneous responses. Interestingly, the sensitivity to sequence and post-error effects varies between the subcomponents. The results indicate that muscle activity can be a useful indicator of response behavior in addition to chronometric parameters.

Response-code conflict in dual-task interference and its modulation by age

Difficulties in performing two tasks at once can arise from several sources and usually increase in advanced age. Tasks with concurrent bimodal (e.g., manual and oculomotor) responding to single stimuli consistently revealed crosstalk between conflicting response codes as a relevant source. However, how this finding translates to unimodal (i.e., manual only) response settings and how it is affected by age remains open. To address this issue, we had young and older adults respond to high- or low-pitched tones with one (single task) or both hands concurrently (dual task). Responses were either compatible or incompatible with the pitch. When responses with the same level of compatibility were combined in dual-task conditions, their response codes were congruent to each other, whereas combining a compatible and an incompatible response created mutually incongruent (i.e., conflicting) response codes, potentially inducing detrimental crosstalk. Across age groups, dual-task costs indeed were overall highest with response-code incongruency. In these trials, compatible responses exhibited higher costs than incompatible ones, even after removing trials with strongly synchronized responses. This underadditive cost asymmetry argues against mutual crosstalk as the sole source of interference and corroborates notions of strategic prioritization of limited processing capacity based on mapping-selection difficulty. As expected, the effects of incongruent response codes were found to be especially deleterious in older adults, supporting assumptions of age-related deficits in multiple-action control at the level of task-shielding. Overall, our results suggest that aging is linked to higher response confusability and less efficient flexibility for capacity sharing in dual-task settings.

Computer-Based Assessment: Dual-Task Outperforms Large-Screen Cancellation Task in Detecting Contralesional Omissions.

Objective: Traditionally, asymmetric spatial processing (i.e., hemispatial neglect) has been assessed with paper-and-pencil tasks, but growing evidence indicates that computer-based methods are a more sensitive assessment modality. It is not known, however, whether simply converting well-established paper-and-pencil methods into a digital format is the best option. The aim of the present study was to compare sensitivity in detecting contralesional omissions of two different computer-based methods: a “digitally converted” cancellation task was compared with a computer-based Visual and Auditory dual-tasking approach, which has already proved to be very sensitive.Methods: Participants included 40 patients with chronic unilateral stroke in either the right hemisphere (RH patients, N = 20) or the left hemisphere (LH patients, N = 20) and 20 age-matched healthy controls. The cancellation task was implemented on a very large format (173 cm × 277 cm) or in a smaller (A4) paper-and-pencil version. The computer-based dual-tasks were implemented on a 15′′ monitor and required the detection of unilateral and bilateral briefly presented lateralized targets.Results: Neither version of the cancellation task was able to show spatial bias in RH patients. In contrast, in the Visual dual-task RH patients missed significantly more left-sided targets than controls in both unilateral and bilateral trials. They also missed significantly more left-sided than right-sided targets only in the bilateral trials of the Auditory dual-task.Conclusion: The dual-task setting outperforms the cancellation task approach even when the latter is implemented on a (large) screen. Attentionally demanding methods are useful for revealing mild forms of contralesional visuospatial deficits.

Automated Prescreening of Mild Cognitive Impairment Using Shank-Mounted Inertial Sensors Based Gait Biomarkers

The mild symptoms in Mild Cognitive Impairment (MCI), a precursor of dementia, often go unnoticed and are assumed as normal aging signs. Such negligence result in late visits which consequently, lead to the diagnosis and progression of dementia. An instrumented gait assessment in home settings may facilitate the detection of subtle MCI-related motor deficits thus, allowing early diagnosis and intervention. This paper investigates potential gait biomarkers derived from shank mounted inertial sensors signals under normal and dual-task walking conditions using data collected from thirty MCI and thirty cognitively normal (CN) subjects. To identify potential gait biomarkers for MCI screening, we assess the variance and predictive power of each feature. Moreover, multiple classification models using different machine learning and feature selection techniques are built to automate MCI detection by leveraging the gait biomarkers. Statistical analysis reveal multiple gait parameters that are significantly different under both single and dual-task settings. However, we show that dual-task walking provides better distinction between MCI and CN subjects. The machine learning model employed for MCI pre-screening based on the inertial sensor-derived gait biomarkers achieves accuracy and sensitivity of 71.67% and 83.33%, respectively.

Task-separation in dual-tasking: How action effects support the separation of the task streams

Dual-task costs might reflect a direct consequence of confusions on the task-set level as both tasks are integrated into a single task-set, instead of two separate task-sets. In order to prevent this integration-driven interference, the two task streams have to be separated. Under three experimental conditions we investigated whether in a dual-task setting such separated task processing can be elicited by providing separated action effects for both tasks. Building on the finding that implicit sequence learning is hampered under dual-tasking conditions, we used it as an indicator for successfully separated task processing. To this end, we compared the implicit sequence learning effect under a single-task condition (baseline condition) to that under a dual-task condition either with separated action effects (action-effect condition) or with conjoined error feedback at the end of each trial (feedback condition): Learning should be unaffected under the former and reduced under the latter experimental condition. In all three conditions, the participants performed a visual-manual and an auditory-manual discrimination task which were always presented concurrently. The results show that, compared to the single-task condition, under dual-task conditions implicit sequence learning is hampered when only a conjoined error feedback is given, but is largely unaffected by dual-tasking when separated action effects are presented. Overall this suggests that whenever two tasks in a dual-task situation appear concurrently, they seem to get integrated into a single task-set by default. Yet, manipulations like the presentation of separated action effects could help to elicit a separated task processing, thus strengthening the representation as two separate task-sets.

Increased reliance on top-down information to compensate for reduced bottom-up use of acoustic cues in dyslexia

Speech recognition is a complex human behavior in the course of which listeners must integrate the detailed phonetic information present in the acoustic signal with their general linguistic knowledge. It is commonly assumed that this process occurs effortlessly for most people, but it is still unclear whether this also holds true in the case of developmental dyslexia (DD), a condition characterized by perceptual deficits. In the present study, we used a dual-task setting to test the assumption that speech recognition is effortful for people with DD. In particular, we tested the Ganong effect (i.e., lexical bias on phoneme identification) while participants performed a secondary task of either low or high cognitive demand. We presumed that reduced efficiency in perceptual processing in DD would manifest in greater modulation in the performance of primary task by cognitive load. Results revealed that this was indeed the case. We found a larger Ganong effect in the DD group under high than under low cognitive load, and this modulation was larger than it was for typically developed (TD) readers. Furthermore, phoneme categorization was less precise in the DD group than in the TD group. These findings suggest that individuals with DD show increased reliance on top-down lexically mediated perception processes, possibly as a compensatory mechanism for reduced efficiency in bottom-up use of acoustic cues. This indicates an imbalance between bottom-up and top-down processes in speech recognition of individuals with DD.

Augmentation Impacts Strategy and Gaze Distribution in a Dual-Task Interleaving Scenario

ABSTRACT When interleaving multiple tasks, people are confronted with a decision of how to distribute a finite amount of time between several tasks, which defines the task-interleaving strategy. In some challenging task interleaving scenarios where accurate timing is essential, people perform worse than they could have. With the growing advancement of technology, such as augmented reality, it became possible to impact people’s strategy and improve their performance. However, when augmenting visual input with additional visual content, the augmentation not only introduces the possible benefit but can also capture attentional resources. It is, thus, important to investigate how visual augmentation affects people’s performance in cases when otherwise people underscore in their performance. In the current study, using a psychophysics approach, it was investigated how visual augmentation impacts the task-interleaving strategy and, thus, performance in a dual-task setting with unequal task importance. In a simple dynamic 3D environment, four visual augmentations were generated aiming to prompt the user when it is more beneficial score-wise to switch from one task to another. The mean duration on one task before the task switch, as well as the resulting total performance, were evaluated in combination with the gaze direction distribution. In terms of the strategy and the total performance, all augmentations showed an advantage compared to when augmentation was not present. Furthermore, an abrupt augmentation onset based on the individual response time of the participant was more beneficial score-wise for the strategy compared to a constantly present visual augmentation. However, it affected the natural gaze direction distribution indicating the allocation of attentional resources to the augmentation. The results of this study provide an insight into potential visual augmentation designs aiming to improve user’s performance in a challenging dual-task interleaving setting.

Association between Balance Confidence and Cognitive-Motor Interference in Stroke Patients – Pilot Study

Background: Functional community ambulation demands the ability to accomplish both mobility andcognitive tasks at the same time (dual-tasking). When gait and cognitive deficits are done concurrently,this is referred to as cognitive-motor interference. Some hypothesis says that Individuals with lowbalance confidence would have higher cognitive-motor interference, indicating a behavioral changeduring dual-task settings. The purpose of this study is to see if cognitive-motor interference is linked tostroke patients’ confidence in their balance.Methodology: The participants in this pilot trial were sub-acute and chronic community-dwelling strokesurvivors. The MFES questionnaire assessed balance confidence. Participants completed four 10-meterwalking trails to evaluate Cognitive-Motor Interference. Two of the walking trails were performedwithout any additional tasks, while the other two were completed with a concurrent cognitive challenge.Conclusion: A total of 30 people participated in this study, with a mean age of 64±7.7 years. Pearsoncorrelation discovered a statistically significant (p=&lt;0.05) negative correlation (r=-0.202) betweenbalance confidence and CMI. This study found that balance confidence is not associated with cognitivemotor interference in stroke patients

A Current View on Dual-Task Paradigms and Their Limitations to Capture Cognitive Load.

Dual-task paradigms encompass a broad range of approaches to measure cognitive load in instructional settings. As a common characteristic, an additional task is implemented alongside a learning task to capture the individual’s unengaged cognitive capacities during the learning process. Measures to determine these capacities are, for instance, reaction times and interval errors on the additional task, while the performance on the learning task is to be maintained. Opposite to retrospectively applied subjective ratings, the continuous assessment within a dual-task paradigm allows to simultaneously monitor changes in the performance related to previously defined tasks. Following the Cognitive Load Theory, these changes in performance correspond to cognitive changes related to the establishment of permanently existing knowledge structures. Yet the current state of research indicates a clear lack of standardization of dual-task paradigms over study settings and task procedures. Typically, dual-task designs are adapted uniquely for each study, albeit with some similarities across different settings and task procedures. These similarities range from the type of modality to the frequency used for the additional task. This results in a lack of validity and comparability between studies due to arbitrarily chosen patterns of frequency without a sound scientific base, potentially confounding variables, or undecided adaptation potentials for future studies. In this paper, the lack of validity and comparability between dual-task settings will be presented, the current taxonomies compared and the future steps for a better standardization and implementation discussed.

Structuralist mental representation of dual-action demands: Evidence for compositional coding from dual tasks with low cross-task dimensional overlap

The present study asks how behavioral (dual-action) demands in dual tasks are mentally represented and whether changes in representation might govern practice-related dual-task performance improvements. Three different representation accounts were empirically tested based on the idea that dual-action demands required in a dual-task trial might be represented in different ways. According to a compositional (Structuralist) account, component tasks remain structurally intact when combined with another task. In contrast, a holistic (Gestalt) account posits that dual-action requirements in dual tasks are represented holistically and entirely distinct from its component action requirements. Finally, a contextual change account assumes that a change in context (e.g., from single- to dual-action requirement) generally impedes response retrieval, similar to repeating a response while the task context switches. To address this issue, we analyzed trial-by-trial effects in a single/dual switch paradigm (SDS paradigm, involving a randomized mix of single- and dual-task trials within blocks). Specifically, we analyzed performance in an extensive dual-task training setting (involving training sessions across several days) combining an auditory-vocal task and a visual-manual task. The results indicated that, throughout practice, nearly all relevant comparisons of performance between complete switch trials (e.g., between the two single tasks) and partial repetition trials (e.g., from dual to single task) revealed partial repetition benefits, that is, for both the auditory-vocal and the visual-manual task, and for both single- and dual-task performance analyses. Therefore, dual-action requirements in the present dual-task setting are mentally represented in a compositional, Structuralist fashion, probably due to low between-task dimensional overlap.

Structuralist Mental Representation of Dual-action Demands: Mechanisms of Improved Dual-task Performance after Practice in Older Adults

ABSTRACT Aim: The present study was designed to investigate how behavioral (dual-action) demands in dual tasks are mentally represented in older adults and how these representations might contribute to the practice-related improvement of dual-task performance. Three different theoretical representation accounts were empirically tested: a structuralist account, a holistic account, and a contextual change account. The first account assumes that component tasks remain structurally intact when combined with another task while the second account assumes that dual-action requirements in dual tasks are represented holistically and entirely distinct from its component (single-action) requirements. The final account assumes that a change in context (e.g., from single to dual requirement) might generally impede response retrieval, similar to repeating a response when the task context switches. Methods: To address this issue of dual-action representations in older adults, we assessed trial-by-trial effects in a single/dual switch paradigm (involving a randomized mix of single- and dual-task trials within blocks). In detail, we re-analyzed a large set of practice data involving seven sessions, in which an auditory-vocal task was combined with a visual-manual task. Results: At the end of practice, the current results were largely consistent with the structuralist account. Conclusions: We conclude that dual-action requirements in the present dual-task setting are mentally represented in a predominantly structuralist fashion at the end of practice in older adults. The results are discussed in the context of other theories on practice-related mechanisms of improved dual-task performance in this age group.