Dual-task Paradigm Research Articles

Tracing executive functions in insight

Usually the central executive is considered as a single capacity in the insight studies which leads to inconsistent results on the link between the central executive of working memory and insight. We suppose a more detailed view on the process of insight solution in which various executive functions could be important at different solution stages: updating is necessary to build a problem’s representation, inhibition—to overcome the impasse, shifting—to restructure the problem’s representation. These assumptions were not confirmed in an experiment via dual-task paradigm and cognitive load. We did not find the relation between executive functions and solution stages, but we demonstrated that the more complexity of dual-task, the more cognitive load in problem solving. Moreover, the highest load of executive functions is observed at the end of insight solution. We speculate that the loading occurs either due to decrease of the free space in working memory storage systems, or due to a resource-intensive event (for example, representational change).

Visual Complexity of Head-Up Display in Automobiles Modulates Attentional Tunneling.

To investigate how the visual complexity of head-up displays (HUDs) influence the allocation of driver's attention in two separate visual domains (near and far domains). The types and amount of information displayed on automobile HUDs have increased. With limited human attention capacity, increased visual complexity in the near domain may lead to interference in the effective processing of information in the far domain. Near-domain and far-domain vision were separately tested using a dual-task paradigm. In a simulated road environment, 62 participants were to control the speed of the vehicle (SMT; near domain) and manually respond to probes (PDT; far domain) simultaneously. Five HUD complexity levels including a HUD-absent condition were presented block-wise. Near domain performance was not modulated by the HUD complexity levels. However, the far domain detection accuracies were impaired as the HUD complexity level increased, with greater accuracy differences observed between central and peripheral probes. Increased HUD visual complexity leads to a biased deployment of driver attention toward the central visual field. Therefore, the formulation of HUD designs must be preceded by an in-depth investigation of the dynamics of human cognition. To ensure driving safety, HUD designs should be rendered with minimal visual complexity by incorporating only essential information relevant to driving and removing driving-irrelevant or additional visual details.

Dual tasking paradigm in clinical stages of early Alzheimer’s disease

AbstractBackgroundIn Alzheimer’s disease (AD) both motor and cognitive domains are impaired [1‐2]. However, these domains are usually assessed independently, even when performing dual‐task (DT) paradigms, the cognitive‐motor interaction (CMI) is not taken into account which may lead to misinterpretation of the patient’s global state. To date, there are no precise markers to neither detect subtle signs of pre‐clinical neurodegeneration nor accurately monitor disease progression.MethodWe have evaluated the motor and cognitive components of a DT paradigm concurrently (Figure 1). 50 participants, aged 60 to 80 years, were included in the study, distributed across four cohorts corresponding to progressive clinical stages of early AD [3]: 1) amyloid negative, cognitively healthy participants (control group), 2) amyloid positive pre‐symptomatic AD, 3) Mild Cognitive Impairment (MCI) due to AD and 4) mild AD. Two inertial measurement units (IMUs) (Physilog, GaitUp S.A.) were attached to each foot to measure gait parameters and a small microphone (Wireless GO, RØDE) was attached to the shirt to record counting. Both timing and gait features were extracted from raw data, however only conventional features, correct response rate (CRR) and gait speed, were considered for this abstract and were used to evaluate the CMI based on Plummer’s classification system [5]. Moreover two‐way ANOVA was carried out to evaluate the effect of cohort and cognitive load conditions on the CMI.ResultOur results show that there is a significant drop in performance at both the cognitive and motor tasks while performing DT and that this drop is more pronounced as we move toward stages of greater cognitive impairment and as we increase the cognitive load of the task (Figure 2). Moreover, CMI shows a cognitive‐priority trade‐off in all cohorts (better/similar counting while slower walking), but movement toward mutual interference effect (worst counting and slower walking) when increasing cognitive load and state of cognitive decline (Figure 3).ConclusionTo our knowledge, this is the first feasibility study assessing the CMI at preclinical and early clinical stages of AD. Our preliminary results suggest that the DT paradigm is a sensitive method to detect early signs of neurodegeneration and monitor AD progression.

Detrimental effects of effortful physical exertion on a working memory dual-task in older adults.

Action and cognition often interact in everyday life and are both sensitive to the effects of aging. The present study tested the effects of a simple physical action, effortful handgrip exertion, on working memory (WM) and inhibitory control in younger and older adults. Using a novel dual-task paradigm, participants engaged in a WM task with 0 or 5-distractors under concurrent physical exertion (5% vs. 30% individual maximum voluntary contraction). Effortful physical exertion, although failing to effect WM accuracy in the distractor absent condition for both age groups, reduced WM accuracy for the older, but not young adults, in the distractor-present condition. Similarly, older adults experienced greater distractor interference in the distractor-present condition under high physical exertion, indexed by slower reaction time (RT), confirmed by hierarchical Bayesian modeling of RT distributions. Our finding that a simple but effortful physical task results in impaired cognitive control may be empirically important for understanding everyday functions of older adults. For example, the ability to ignore task-irrelevant items declines with age and this decline is greater when simultaneously performing a physical task, which is a frequent occurrence in daily life. The negative interactions between cognitive and motor tasks may further impair daily functions, beyond the negative consequences of reduced inhibitory control and physical abilities in older adults. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Dyspnea induced by inspiratory loading limits dual-tasking in healthy young adults.

Dyspnea is a common and multidimensional experience of healthy adults and those with respiratory disorders. Due to its neural processing, it may limit or interfere with cognition, which may be examined with a dual-task paradigm. The aim of this study was to compare single-task performance of Stroop Colour and Word Test (SCWT) or inspiratory threshold loading (ITL) to their combined dual-task performance. Secondly, whether mood was related to dyspnea or cognitive performance was also evaluated. A virtual pre-post design examined single (SCWT and ITL) and dual-task (SCWT+ITL) performance. For ITL, a Threshold Trainer™ was used to elicit a "somewhat severe" rating of dyspnea. The SCWT required participants to indicate whether a colour-word was congruent or incongruent with its semantic meaning. The Depression, Anxiety and Stress Scale-21 (DASS-21) was completed to assess mood. Breathing frequency, Borg dyspnea rating, and breathing endurance time were ascertained. Thirty young healthy adults (15F, 15M; median age = 24, IQR [23-26] years) completed the study. SCWT+ITL had lower SCWT accuracy compared to SCWT alone (98.6%, [97.1-100.0] vs 99.5%, [98.6-100.0]; p = 0.009). Endurance time was not different between ITL and SCWT+ITL (14.5 minutes, [6.9-15.0]) vs 13.7 minutes, [6.1-15.0]; p = 0.59). DASS-21 scores positively correlated with dyspnea scores during ITL (rho = 0.583, p<0.001) and SCWT+ITL (rho = 0.592, p<0.001). ITL significantly reduced dual-task performance in healthy young adults. Lower mood was associated with greater perceived dyspnea during single and dual-task ITL. Considering the prevalence of dyspnea in respiratory disorders, the findings of this dual task paradigm warrant further exploration to inform dyspnea management during daily activities.

Dual-tasking while using two languages: Examining the cognitive resource demands of cued and voluntary language production in bilinguals.

The way bilinguals switch languages can differ depending on the context. In cued dual-language environments, bilinguals select a language in response to environmental cues (e.g., a monolingual conversation partner). In voluntary dual-language environments, bilinguals communicating with people who speak the same languages can use their languages more freely. The control demands of these types of language-production contexts, and the costs of language switches, have been argued to differ (Adaptive Control Hypothesis). Here, we used a dual-task paradigm to examine how cued and voluntary bilingual production differ in cognitive resources used. Forty Mandarin-English bilinguals completed two language-switching paradigms as the primary task; one in response to cues and one while using two languages freely. At the same time, they also had to respond to the pitch of tones (secondary task). Response times (RTs) on the secondary task, as well as naming times on the primary task, were shorter under the voluntary- than cued-naming condition. Task workload ratings were also higher under the cued- than voluntary-naming condition. This suggests more attentional resources are needed in a cued-naming context to monitor cues and select languages accordingly. However, the costs associated with switching from one language to the other were similar in both voluntary- and cued-naming contexts. Thus, while cued-naming might be more effortful overall, cued and voluntary switching recruited similar levels of cognitive resources.

Neural α Oscillations and Pupil Size Differentially Index Cognitive Demand under Competing Audiovisual Task Conditions.

Cognitive demand is thought to modulate two often used, but rarely combined, measures: pupil size and neural α (8-12 Hz) oscillatory power. However, it is unclear whether these two measures capture cognitive demand in a similar way under complex audiovisual-task conditions. Here we recorded pupil size and neural α power (using electroencephalography), while human participants of both sexes concurrently performed a visual multiple object-tracking task and an auditory gap detection task. Difficulties of the two tasks were manipulated independent of each other. Participants' performance decreased in accuracy and speed with increasing cognitive demand. Pupil size increased with increasing difficulty for both the auditory and the visual task. In contrast, α power showed diverging neural dynamics: parietal α power decreased with increasing difficulty in the visual task, but not with increasing difficulty in the auditory task. Furthermore, independent of task difficulty, within-participant trial-by-trial fluctuations in pupil size were negatively correlated with α power. Difficulty-induced changes in pupil size and α power, however, did not correlate, which is consistent with their different cognitive-demand sensitivities. Overall, the current study demonstrates that the dynamics of the neurophysiological indices of cognitive demand and associated effort are multifaceted and potentially modality-dependent under complex audiovisual-task conditions.SIGNIFICANCE STATEMENT Pupil size and oscillatory α power are associated with cognitive demand and effort, but their relative sensitivity under complex audiovisual-task conditions is unclear, as is the extent to which they share underlying mechanisms. Using an audiovisual dual-task paradigm, we show that pupil size increases with increasing cognitive demands for both audition and vision. In contrast, changes in oscillatory α power depend on the respective task demands: parietal α power decreases with visual demand but not with auditory task demand. Hence, pupil size and α power show different sensitivity to cognitive demands, perhaps suggesting partly different underlying neural mechanisms.

Processing cost effects of atypicality inferences in a dual-task setup

Whether pragmatic inferences are cognitively more effortful than processing literal language has been a longstanding question in pragmatics. So far, experimental studies have exclusively tested generalized (scalar) implicatures. Current theories would predict that particularized implicatures should be cognitively effortful – however, this prediction has to date not been tested empirically. The present article contributes to the debate by investigating a specific type of particularized implicature, atypicality inferences, in a dual-task paradigm. In three experiments, we used either a non-linguistic (Experiment 1) or a linguistic (Experiments 2 and 3) secondary task, to modulate the amount of available cognitive resources. Our results show that the strength of pragmatic inferences is largely unaffected by the secondary task, which contrasts with prior predictions. We discuss the implications for traditional and modern accounts of pragmatic processing.

Dual-task decrements in mono-, bi- and multilingual participants: Evidence for multilingual advantage

ABSTRACT Evidence suggests that language processing in bilinguals is less left-lateralized than in monolinguals. We explored dual-task decrement (DTD) for mono-, bi- and multilinguals in a verbal-motor dual-task paradigm. We expected monolinguals to show greater DTD than bilingual participants, who would show greater DTD than multilingual participants. Fifty right-handed participants (18 monolingual, 16 bilingual, 16 multilingual) completed verbal fluency and manual motor tasks in isolation and concurrently. Tasks were completed twice in isolation (left-handed, right-handed) and twice as dual-tasks (left-handed, right-handed); participants’ motor-executing hands served proxy for hemispheric activation. Results supported the hypotheses. Completing dual-tasks incurred greater cost for manual motor tasks than for verbal fluency tasks. Negative cost of performing dual-tasks diminished as number of languages spoken increased; in fact, multilingual individuals demonstrated a dual-task advantage in both tasks when using the right hand, strongest in the verbal task. Dual-tasking had the greatest negative impact on verbal fluency of monolingual participants when the motor task was completed with the right hand; for bi- and multi-lingual participants, the greatest negative impact on verbal fluency was seen when the motor task was completed with the left hand. Results provide support for the bi-lateralization of language function in bi- and multilingual individuals.

Work performance in industry: The impact of mental fatigue and a passive back exoskeleton on work efficiency

Mental fatigue (MF) is likely to occur in the industrial working population. However, the link between MF and industrial work performance has not been investigated, nor how this interacts with a passive lower back exoskeleton used during industrial work. Therefore, to elucidate its potential effect(s), this study investigated the accuracy of work performance and movement duration through a dual task paradigm and compared results between mentally fatigued volunteers and controls, with and without the exoskeleton. No main effects of MF and the exoskeleton were found. However, when mentally fatigued and wearing the exoskeleton, movement duration significantly increased compared to the baseline condition (βMF:Exo = 0.17, p = .02, ω2 = .03), suggesting an important interaction between the exoskeleton and one's psychobiological state. Importantly, presented data indicate a negative effect on production efficiency through increased performance time. Further research into the cognitive aspects of industrial work performance and human-exoskeleton interaction is therefore warranted.

Functional brain changes in sarcopenia: evidence for differential central neural mechanisms in dynapenic older women

BackgroundThe European Working Group on Sarcopenia in Older People (EWGSOP2) recently revised its definition and diagnostic criteria for sarcopenia, placing muscle strength at the forefront. The pathogenesis of dynapenia (or low muscle strength) is still not fully understood, but there is emerging evidence that central neural factors constitute critical determinants.MethodsOur cross-sectional study included 59 community-dwelling older women (mean age 73.1 ± 4.9 years). Participants underwent detailed skeletal muscle assessments for muscle strength defined by handgrip strength and chair rise time measurements using the recently published EWGSOP2 cut-off points. Functional magnetic resonance imaging (fMRI) was assessed during the performance of a cognitive dual-task paradigm, consisting of a baseline, two single-tasks (motor and arithmetic) and one dual-task (motor and arithmetic combined).ResultsForty-seven percent (28/59) of participants were classified as dynapenic. fMRI results revealed a differential recruitment of motor circuits in the brain during the dual-task condition in dynapenic as compared with non-dynapenic participants. In particular, while the brain activity during the single-tasks did not differ between the two groups, only during the dual-task non-dynapenic participants showed significant increased activation in dorsolateral prefrontal and premotor cortex, and in supplementary motor area as compared to dynapenic participants.ConclusionOur results point to a dysfunctional involvement of brain networks associated with motor control in dynapenia in a multi-tasking paradigm. A better knowledge of the link between dynapenia and brain functions could provide new impulses in the diagnosis and interventions for sarcopenia.

Spatiotemporal Parameters of Gait Among Adolescent Athletes with Concussion When Performing a Visuospatial Cognitive Task.

Adolescent athletes aged 10 to 19 years are at the highest risk of experiencing sport-related concussions (SRCs). Despite the known deficits and battery of assessments following concussion, postural stability during dual-task gait remains understudied in this population. The purpose of this study was to evaluate the dual-task cost (DTC) in adolescents with an acute or chronic SRC compared to reference values from healthy athlete peers for spatiotemporal parameters of gait during walking with and without a concurrent visuospatial memory task presented on a hand-held tablet. Researchers hypothesized that adolescents during the acute phase of concussion would be likely to experience a greater DTC compared to healthy peers in at least one spatiotemporal parameter of gait when walking within the dual-task paradigm. Cross-sectional, observational cohort design. Adolescents with concussion were recruited to participate. Subjects were divided into acute and chronic categories based on significant differences in the neuropsychological function after a period of 28 days. They walked at a self-selected speed along the 5.186-meter GAITRite® Walkway System with and without a concurrent visuospatial cognitive task presented on a hand-held tablet. Outcomes included normalized velocity (m/s), step length (m), and double limb (DLS) and single limb support (SLS) (defined as the percent of a gait cycle [%GC]). The data were then compared to the previously published reference values established using the same methods in the healthy athlete participants for all spatiotemporal parameters of gait. Data was collected on 29 adolescent athletes with SRC. Among males (15.53+/-1.12 years) with SRC, 20% of acute and 10% of chronic cases experienced a greater DTC compared to healthy athlete reference values. A similarly increased DTC was experienced by 83% of acute and 29% of chronic SRC cases for females (15.58+/-1.16 years). Adolescent athletes with concussion may continue demonstrating deficits in gait capabilities even in the chronic phase, and compensatory gait strategies were not the same between males and females. Dual-task cost assessment using the GAITRite® may be a valuable adjunct to comprehensive analysis of gait following SRC. 2.

High visual perceptual load reduces prepulse inhibition induced by task-unrelated and task-related sound.

Prepulse inhibition (PPI) is an automatic and pre-attentive sensorimotor gating process. Several studies have shown that advanced cognitive functions can modulate PPI. This study aimed to further elucidate the modulatory effect of attentional resource allocation on PPI. We examined the differences in PPI between high and low attentional loads. First, we verified that the adapted feature versus combination visual search paradigm could produce high and low perceptual load differences according to the task demands. Second, we measured the participants' task-unrelated PPI during the visual search task and found that the PPI in the high-load condition was significantly lower than that in the low-load condition. To further elucidate the role of attentional resources, we tested task-related PPI using a dual-task paradigm in which participants were instructed to complete a visual task with an auditory discrimination task. We found a result similar to that of the task-unrelated experiment. The participants in the high-load condition had less PPI than those in the low-load condition. Finally, we ruled out the possibility that the working memory load explains the modulation of PPI. In line with the theory of PPI modulation, these results suggest that allocating limited attentional resources to the prepulse modulates PPI. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Muscular and Prefrontal Cortex Activity during Dual-Task Performing in Young Adults

Postural control depends on attentional resources besides automatic processes. The dual-task paradigm is a possible approach to analyzing the interference and performance between motor and/or cognitive tasks. Various studies showed that, when individuals simultaneously perform two tasks, the postural stability can decline during a dual-task compared with a single-task due to the attentional resources required performing the tasks. However, little is known about the cortical and muscular activity pattern during dual-task performance. Therefore, this study aims to analyze the muscular and prefrontal activity under dual-task performance in healthy young adults. Thirty-four healthy young adults (mean age ± SD = 22.74 ± 3.74 years) were recruited to perform a postural task (standing posture) and a dual-task (maintaining standing posture while performing a cognitive task). Lower-limb muscle activity was bilaterally collected from five muscles using surface electromyography (sEMG), and the co-contraction index (CCI) was also calculated for selected muscle pairings. The oxy- and deoxyhemoglobin concentrations (prefrontal cortex activity) were recorded using functional near-infrared spectroscopy (fNIRS). Data were compared between single- and dual-task performance. Prefrontal activity increased (p < 0.05), and muscle activity decreased in most analyzed muscles (p < 0.05), from the single-task to cognitive dual-task performing. The co-contraction index patterns changed from single- to dual-task conditions in most selected muscle pairs (p < 0.05). We conclude that the cognitive task negatively interfered with motor performance once the muscle activity decreased and the prefrontal cortex activity increased under a dual-task, suggesting that young adults prioritized cognitive task performance, and they allocated more attentional resources to the cognitive task over the motor performance. Understanding the neuromotor changes can help adopt a better clinical practice to prevent injuries. However, future studies are recommended to assess and monitor muscular and cortical activity during the dual-task performance to provide additional information about the cortical and muscular activity patterns in postural control while performing a dual-task.

Dual-Task Paradigm Measures of Listening Effort: To Include or Not to Include Secondary Task Responses with Incorrect Primary Task Responses.

Response time-based dual-task paradigms are commonly adopted to measure behavioral listening effort. Most extant studies used an all-response approach that included secondary task responses under both correct and incorrect primary task responses during analysis. However, evidence supporting this strategy is limited. Therefore, the current study investigated the potential differences between including all responses versus only including correct responses. Data from two previous studies were reanalyzed. Experiment 1 included 16 listeners and used a dual-task paradigm to examine the effect of introducing background noise on listening effort. Experiment 2 included 19 participants and used a different dual-task paradigm to examine the effect of reverberation and loudspeaker-to-listener distance on listening effort. ANOVA results obtained using both analysis approaches were compared. The all-response and correct-only approaches revealed similar results. However, larger effect sizes and an additional main effect were found with the all-response approach. The current study supports the use of an all-response approach due to its greater sensitivity to changes in behavioral listening effort. However, a correct-only approach could be utilized to suit specific study purposes.

Attentional allocation and the pan-field color illusion.

Humans subjectively experience a scene as rendered in color across the entire visual field, a visual phenomenon called "pan-field color" (Balas & Sinha, 2007). This experience is inconsistent with the limited color sensitivity in the peripheral visual field. We investigated the effects of visual attention allocated to the peripheral visual field on the pan-field color illusion. Using "chimera" stimuli in which color was restricted to a circular central area, we assessed observers' tendency to perceive color throughout images with achromatized peripheral regions. We separately analyzed sensitivity and response bias in judging the color content of the scene image as full-color, chimera, or gray. Using a dual-task paradigm, we manipulated observers' attentional allocation by controlling the stimulus presentation time of the central task, making the foveal attentional load change. The slope of the foveal load-sensitivity function suggests that attention was modulated by foveal load even in the peripheral visual field. Bias was affected by the size of the central colored area, such that the tendency to answer "full-color" to the chimera image increased with eccentricity. Based on these effects of attention on sensitivity and bias, we suggest that the pan-field color illusion cannot be fully explained by the decrease of sensitivity that is modulated by attentional allocation in the periphery. Our results rather indicate that the pan-field color illusion at least partly reflects a liberal bias in peripheral vision.

The role of line-orientation processing in the production of the Poggendorff illusion: A dual-task study.

Using a dual-task paradigm, the present investigation examined whether processes related to line orientation play a critical role in the production of the Poggendorff illusion. In Experiment 1, we assessed the magnitude of the Poggendorff illusion under three different task conditions. In the single-task condition, participants were asked to report how they perceive the alignment of transversal lines in the Poggendorff figure. In two different dual-task conditions, the participants were asked to read aloud the time displayed on a digital or analogue clock while also performing the Poggendorff perception task. The method of constant stimuli was used to calculate the point of subjective equality (PSE) and bistability width values, which represent illusion strength and perceptual uncertainty, respectively. PSEs indicated that the magnitude of the illusion did not vary between single, dual-analogue, and dual-digital task conditions, which suggests that the additional demands placed by the dual tasks had no effect on the illusion strength. Perceptual uncertainty and clock-reading errors were greater in the dual-analogue task condition. Experiment 2 revealed that the analogue clockface was more difficult to read than the digital clockface. Based on these results, we conclude that having participants perform a secondary task does not influence the magnitude of the Poggendorff illusion.

The predictive relationships between advanced dynamic balance and physical activity/quality of life in Parkinson's disease

Gait and balance problems commonly occur in Parkinson's disease (PD). However, balance tasks with only one performance objective (e.g., sit-to-stand) may not be sufficient, compared to dual motor tasks (e.g., carrying a tray while walking), to be applied to the assessments and interventions which are designed to promote PD patients' balance functioning, physical activity (PA) and health-related quality of life (HQoL). The aim of this study, therefore, was to determine whether advanced dynamic balance, measured by a demanding motor-motor dual task, is a significant predictor of PA/HQoL in older adults with and without PD. Participants with (n = 22) and without (n = 23) PD were assessed using the Berg Balance Scale (BBS), the single leg hop and stick series task (SLHS), the Physical Activity Scale for the Elderly (PASE), and the Parkinson's Disease Questionnaire–39 (PDQ39). We calculated the R2 change, namely the incremental validity, between the multiple regression models before and after adding the scores on the BBS/SLHS. While controlling for biological and socioeconomic covariates, competence in the SLHS task provided moderate and large levels of incremental validity to PA (ΔR2 = 0.08, Cohen's f2 = 0.25, p = .035) and HQoL (ΔR2 = 0.13, Cohen's f2 = 0.65, p < .001), respectively. In particular for participants with PD, the SLHS explained significantly more variance in HQoL in relation to psychosocial functioning (ΔR2 = 0.25, Cohen's f2 = 0.42, p = .028) compared to the BBS (p = .296). Assessing advanced dynamic balance by means of a highly demanding dual-task paradigm was not only strongly associated with PA but also covered a wider spectrum of HQoL components. This approach is recommended for use in evaluations and interventions carried out in clinical and research settings in order to promote healthy living.

Disentangling working memory from multiple-object tracking: Evidence from dual-task interferences.

Multiple object tracking (MOT) is generally regarded as a pure attention-consuming task that draws heavily on attention resources. In the present study, we adopted a cross-channel visual-audio dual-task paradigm, i.e., the MOT task combined with the concurrent auditory N-back working memory task, to test whether working memory indeed plays a necessary role in the process of multiple tracking, as well as to further identify the specific types of working memory components involved in this process. Experiments 1a and 1b examined the relationship between the MOT task and nonspatial object working memory (OWM) processing by manipulatingthe tracking load and working memory load, respectively. Results in both experiments indicated that the concurrent nonspatial OWM task did not have a significant effect on the tracking capacity of the MOT task. In contrast, Experiments 2a and 2b examined the relationship between the MOT task and spatial working memory (SWM) processing by a similar approach. Results in both experiments indicated that the concurrent SWM task significantly impaired the tracking capacity of the MOT task, showing a gradual decrease with increasing SWM load. Overall, our study provides empirical evidence that multiple object tracking does involve working memory, primarily related to spatial working memory rather than nonspatial object working memory, which sheds more light on the mechanisms of multiple object tracking.

Speech intelligibility and listening effort: A dual-task paradigm for accented speech perception

Unfamiliar accents can make speech communication difficult, both by reducing speech intelligibility and by increasing the effort listeners must put forth to understand speech. In general, intelligibility refers to the proportion of words that a listener can correctly identify (100%, 50%, etc.), while listening effort refers to the cognitive resources that must be devoted to a difficult listening task. Generally, lower intelligibility is related to higher effort. However, it is now apparent that these two constructs, while related, are independent: for example, two 100% intelligible speakers may elicit different amounts of effort. To better characterize the relationship between intelligibility and effort, this study presents speakers of four intelligibility levels (one L1 English speaker, and three Mandarin-accented English speakers) within a dual-task paradigm (featuring a vibrotactile secondary task) to measure listening effort. We hypothesize an inverse relationship between intelligibility and effort, but the shape and slope of this relationship are of primary interest. These results will begin to illuminate the relationship between intelligibility and effort across a more continuous range of accent intelligibility. Data collection is ongoing. Results for the Mandarin Chinese accent will be presented. Preliminary results for the study’s second iteration (using a Korean accent) will also be presented.