Concurrent Task Conditions Research Articles

Effectiveness of Concurrent Performance of Military and Robotics Tasks and Effects of Cueing in a Simulated Multi-Tasking Environment

We simulated a military mounted crewstation environment and conducted two experiments to examine the workload and performance of the combined position of gunner and robotics operator. The robotics tasks involved managing a semi-autonomous ground robot or teleoperating a ground robot to conduct reconnaissance tasks. We also evaluated whether aided target recognition (AiTR) capabilities (delivered either through tactile or tactile + visual cueing) for the gunnery task might benefit the concurrent robotics and communication tasks. Results showed that participants' gunnery task performance degraded significantly when s/he had to concurrently monitor, manage, or teleoperate a robot compared to the gunnery-single task condition. When there was AiTR to assist them with their gunnery task, operators' concurrent performance of robotics and communication tasks improved significantly. However, there was a tendency for participants to over-rely on automation when taskload was heavy, and performance degradations were observed in instances where automation failed to be entirely reliable. Participants' spatial ability was found to be a reliable predictor of robotics task performance. Participants' perceived workload increased consistently as the concurrent task conditions became more challenging and when their gunnery task was unassisted.

Effects of response–stimulus interval manipulation and articulatory suppression on task switching

We conducted three experiments using a list paradigm to examine how articulatory suppression and response–stimulus interval (RSI) manipulation affected task switching. Experiments 1 and 2 tested task-switching performance under a short and long RSI and three concurrent task conditions (control, articulatory suppression, and tapping) without external task cues. The results indicated that alternation had a greater effect under articulatory suppression than under the control and tapping conditions, and that articulatory suppression costs were unrelated to the RSI. In Experiment 3, an external task cue was provided with each stimulus, and the negative effect of articulatory suppression on alternation cost was eliminated. These results indicated that articulatory suppression effects did not differ between conditions of short and long RSI and that the availability of verbal representations of task information was independent of RSI length. This paper discussed the possible roles played by the phonological loop in task-switching paradigms.

Age-related changes in duration reproduction: Involvement of working memory processes

The aim of the present research was to study age-related changes in duration reproduction by differentiating the working memory processes underlying this time estimation task. We compared performances of young and elderly adults in a duration reproduction task performed in simple and concurrent task conditions. Participants were also administered working memory tests to measure storage and central executive functions. Findings indicated a differential involvement of working memory storage and central executive functions in age-related differences in temporal tasks. The limited storage capacities explained age-related changes in the simple task of duration reproduction, and the dysfunctioning of central executive functions accounted for age-related changes in duration reproduction performed in a concurrent task condition, which involves greater attentional resources.

Motor Learning of a Dynamic Balancing Task After Stroke: Implicit Implications for Stroke Rehabilitation

After a stroke, people often attempt to consciously control their motor actions, which, paradoxically, disrupts optimal performance. A learning strategy that minimizes the accrual of explicit knowledge may circumvent attempts to consciously control motor actions, thereby resulting in better performance. The purpose of this study was to examine the implicit learning of a dynamic balancing task after stroke by use of 1 of 2 motor learning strategies: learning without errors and discovery learning. Ten adults with stroke and 12 older adults practiced a dynamic balancing task on a stabilometer under single-task (balance only) and concurrent-task conditions. Root-mean-square error (in degrees) from horizontal was used to measure balance performance. The balance performance of the discovery (explicit) learners after stroke was impaired by the imposition of a concurrent cognitive task load. In contrast, the performance of the errorless (implicit) learners (stroke and control groups) and the discovery learning control group was not impaired. The provision of explicit information during rehabilitation may be detrimental to the learning/relearning and execution of motor skills in some people with stroke. The application of implicit motor learning techniques in the rehabilitation setting may be beneficial.

Speech Interactions With Linguistic, Cognitive, and Visuomotor Tasks

Lip movements were examined across several repetitive speaking conditions (speech alone and speaking concurrently with a linguistic, cognitive, or visuomotor challenge task) in 20 young adults. Performance in these nonspeech activities was also compared between isolated tasks and concurrent speech conditions. Linguistic challenges resulted in increased spatiotemporal variability of lip displacement across repetitions. Motor challenges led to more rapid speech with smaller lip displacement. These qualitatively different changes suggest that different aspects of attention are required for linguistic versus manual visuomotor activity. Vocal intensity increased for all concurrent task conditions compared with speech alone, suggesting increased effort compared to the control condition. Scores for linguistic performance decreased when utterance repetition occurred concurrently with the syntactic challenge. These findings reveal that speech motor activity can influence linguistic performance as well as be influenced by it. Although these data come from healthy speakers, they suggest that clinicians working with disordered speakers should not overlook the potential interactions among the demands of language formulation, cognitive activity, and speech motor performance.

Visuo-spatial processing in Parkinson's disease: evidence for diminished visuo-spatial sketch pad and central executive resources

A dual-task study compared the visuo-spatial sketch pad and central executive components of working memory as potential cognitive mechanisms of visuo-spatial dysfunction in Parkinson's disease. Mildly to moderately affected Parkinsonian patients ( n=15) and controls ( n=15) performed the Corsi blocks task concurrently with tasks designed to load on the visuo-spatial sketch pad (spatial tapping) or the central executive (random interval repetition). Patients performed more poorly in both concurrent task conditions, implicating a reduction in both visuo-spatial sketch pad and central executive resources. The impact of the concurrent tasks varied with disease severity, with the central executive deficit prominent at disease onset, but the visuo-spatial sketch pad deficit becoming apparent only in the moderate stages of the illness.

The Effect of a Concurrent Task on Parkinsonian Speech

The aim of the study was to examine the role of attention in Parkinsonian speech control, by using a dual-task paradigm. Whilst it is well-known that skeletal motor performance is impaired when Parkinson's disease (PD) patients are required to perform two motor acts simultaneously, this has not been examined in the context of speech motor control. Fifteen idiopathic PD patients and matched controls performed two speech tasks (spontaneous conversation and numerical recitation), with and without simultaneous engagement on a visuo-manual tracking task. Volumetric and temporal parameters of speech control were examined. The findings show a trend towards reduced overall speech volume, and a significant increase in progressive volume decay for patients relative to controls, for the concurrent task condition. Patients' speech was also characterised by increased speech initiation time and pause time, while speech rate was reduced upon introduction of the concurrent task. Performance on the visuo-motor task by patients, however, was similar to that of controls. The PD patients demonstrated a deterioration of volumetric and temporal measures of speech motor control, when attentional resources were reduced by a distractor task. Consistent with dual-task studies of skeletal movement control, these findings also show that there is a Parkinsonian disadvantage for the more automatic and non-visually controlled task, that is, speech, in the present study. It is, therefore, suggested that speech and skeletal movement control are similarly driven by the higher-order frontostriatal impairment inherent in PD.

Working memory for movement patterns: a direct comparison of memory spans for body and hand movements in dual-task situations

In this experiment, 36 participants engaged in one of three span tasks; digit span, body movement span, or hand movement span task, in which they were asked to remember visually presented sequences of digits, whole body movement patterns, or hand movement patterns, respectively. As in a standard memory span procedure, the items within each sequence were recalled in order. Participants were presented with increasingly longer sequences of the items, and span score was defined as the number of items in the longest sequence a participant could recall perfectly. The span tasks were tested under three concurrent task conditions; no concurrent task control, concurrent articulation task, and concurrent body-related movement task. The concurrent movement task interfered with performance on both body movement and hand movement span tasks, but not on the digit span task, while the concurrent articulation task interfered with performance on all of the three span tasks. It is suggested that memory for movement patterns, which is involved in the body and band movement spans, would be mediated by a common motor-processing system.

THE NEED FOR CONTROLLED INFORMATION PROCESSING IN THE VISUAL ACQUISITION OF ROUTE KNOWLEDGE

The route knowledge of participants who performed a concurrent task during a simulated route-learning exercise was compared to that of participants engaged only in the route-learning exercise by employing tests of scene recognition, distance estimation and map verification. Results indicated performance decrements on the scene recognition and distance estimation tasks on the part of participants in the concurrent task condition, thus supporting the interpretation that these tasks were sensitive to the reduction in available attentional resources. Performance on the map verification task was generally poor, a fact that may have masked the general effect of the concurrent task manipulation. Comparisons involving only those subgroups for which performance was above chance level provided evidence that this task was also sensitive to the availability of resources. In addition, results from the map verification task clearly pointed to map orientation as an important factor influencing the ability to recognize a cartographic representation of a path of movement within a large-scale environment.

Effect of repetition on grammaticality judgments under objective and subjective self-awareness conditions

Three experiments were performed to investigate the differential effect of repeated presentation of sentences on judgments of grammaticality under the two mental states of objective and subjective self-awareness. In Experiment 1, 22 students judged the relative grammaticality of sentences twice, receiving a repetition treatment between the two judgments. During the repetition phase, they were exposed to a repeated presentation of sentences. The findings showed that repetition makes a judgment criterion more stringent on judgments after repetition than on those before repetition for the subjectively self-aware subjects, while it does not influence the judgments for the objectively self-aware subjects. Experiment 2 was run using a revised procedure with 26 students. The findings showed the expected, interaction, such that the repetition makes a criterion stringent for the subjectively self-aware subjects while it makes the criterion lenient for the objectively self-aware subjects. Experiment 3 examined with 12 students whether the finding for the latter subjects could be explained, by divided attention theory in a concurrent task condition. The findings showed no change of judgment criterion. These findings indicate that repeated exposure to the sentences exerts differential effects on grammaticality judgments dependent on whether the subjects are objectively or subjectively self-aware.

The Influence of Brain Lateralization of Function on a Manual Skill

The present study considers the predictions of the brain lateralization of function hypothesis for the concurrent-task situation where the subject is required, to perform simultaneously a manual and a cognitive task. The manual task required the subject to successively press two keys with either the right or left hand, this being done concurrently with one of twelve different cognitive tasks. The cognitive tasks varied in terms of their verbal (left hemisphere) and non-verbal (right hemisphere) attributes. The results indicate that, for the concurrent verbal task conditions, only right-hand performance was disrupted while left-hand performance remained unchanged. For the non-verbal conditions both left and right hand performance was disrupted. These findings were interpreted in terms of brain lateralization of cognitive functions and possible hemispheric processes controlling manual performance.