Continuous Task Research Articles

Contributions of open-loop and closed-loop control in a continuous tracking task differ depending on attentional demands during practice.

Improving tracking performance requires numerous adjustments in the motor system, including peripheral muscle functions and central motor commands. These commands can rely on sensory feedback processing during tracking, i.e., closed-loop control. In the case of repeated tracking sequences, these commands can rely on an inner representation of the target trajectory to optimize pre-planning, i.e., open-loop control. Implicit learning in a continuous tracking task with repeated sequences proves the availability of an inner target representation, which emerges by learning task regularities, even without explicit knowledge. We hypothesize that the actual use of open-loop or closed-loop control is influenced by the demand for attention. Specifically, we suggest that closed-loop control and its development during practice need attentional resources, whereas open-loop control can work and evolve in a more automatic way without attentional demands. To test this, we investigated motor-control strategies when extensively practicing a continuous compensatory force-tracking task using isometric leg muscle activation, either as a single-motor task or as a motor-cognitive dual task. After training, we found evidence for predominantly closed-loop control in the single-task training group and for open-loop control in the dual-task training group. In particular, we ascertained dual-task motor costs and a weakly developed implicit knowledge of task regularities in the single-task training group. In contrast, in the dual-task training group dual-task motor costs disappeared, while implicit learning was clearly observed. We conclude that motor-cognitive dual-task training may boost implicit motor learning, without necessarily impeding concurrent improvement in the cognitive task. Data repository: reserved doi: https://doi.org/10.5281/zenodo.6759377.

APD: Learning Diverse Behaviors for Reinforcement Learning Through Unsupervised Active Pre-Training

Unsupervised pre-training in reinforcement learning enables the agent to gain prior environmental knowledge, which is then fine-tuned in the supervised stage to quickly adapt to various downstream tasks. In the absence of task-related rewards, pre-training aims to acquire policies (i.e., behaviors) that generate different trajectories to explore and master the environment. Previous research categorizes states into their associated behaviors by learning a supervised discriminator. However, an underlying problem persists: such discriminator is trained in lack of relevant data, leading to an underestimation of reward for new states and inadequate exploration. To this end, we introduce an unsupervised active pre-training algorithm for diverse behavior induction (APD). We explicitly characterize the behavior variables with a state-dependent sampling method, and the agent can decompose the entire state space into parts for fine-grained and diverse behavior learning. Specifically, a particle-based entropy estimator is applied to optimize a combination of behavioral entropy and mutual information objective. Moreover, we develop behavior-based representation learning to compress states into the latent space. Experiments show that our method can improve exploration efficiency and outperforms most state-of-the-art unsupervised algorithms on a number of continuous control tasks in the DeepMind Control Suite.

Movement Variability and Loading Characteristics in Athletes With Athletic Groin Pain: Changes After Successful Return to Play and Compared With Uninjured Athletes.

Athletic groin pain (AGP) can lead to altered movement patterns during rapid deceleration and acceleration. However, the effect of AGP on movement variability and loading patterns during such actions remains less clear. To investigate, using a continuous lateral hurdle hop task, how movement variability and magnitude measures of 3-dimensional (3D) kinematic, kinetic, and vertical ground-reaction force (vGRF) variables are (1) affected by AGP (AGP vs uninjured controls [CON]) and (2) changed after successful rehabilitation (AGP prerehabilitation vs AGP postrehabilitation vs CON). Controlled laboratory study. A total of 36 athletes diagnosed with AGP and 36 uninjured CON athletes matched on age (18-35 years), level (subelite), and type of sports played (multidirectional field sport) performed a continuous lateral hurdle hop test that involved 10 side-to-side hops over a 15-cm hurdle. The 3D joint kinematic, kinetic, and vGRF variables (total, eccentric, and concentric; ground contact time, peak force, and impulse; and eccentric rate of force development) were examined. The AGP and CON groups were tested at baseline, and the AGP group was retested after participants successfully completed a standardized, exercise-based rehabilitation program targeting intersegmental control. There were no differences in baseline characteristics between the AGP (mean ± SD: age, 27.5 ± 4.8 years; height, 179.8 ± 6.3 cm; mass, 80.3 ± 7.1 kg) and CON (mean ± SD: age, 24.1 ± 4.5 years; height, 181.0 ± 5.8 cm; mass, 80.4 ± 8.2 kg) groups. At baseline, athletes with AGP demonstrated altered loading patterns in the vGRF (longer ground contact times, reduced peak force, and reduced rate of force development) compared with CON athletes, while no significant difference in any movement variability variables was evident. After rehabilitation, the athletes with AGP demonstrated significant changes in transverse and coronal plane hip and trunk kinematics, with no significant differences in vGRF variables compared with the CON group. The differences in baseline vGRF measures between the AGP and CON groups were no longer evident after athletes with AGP underwent rehabilitation. No differences in movement variability were evident between the AGP and CON groups, either before or after rehabilitation. Rehabilitation programs should consider targeting intersegmental hip and trunk movement patterns to positively influence loading patterns in athletes with AGP.

SPAS: Smart Pothole-Avoidance Strategy for Autonomous Vehicles

Autonomous Vehicles (AVs) are a significant part of Vehicular Adhoc NETwork (VANET) as they increase transportation accessibility. However, the presence of unpredictably sized potholes on road surfaces hampers the comfort and safety of autonomous navigation. Existing pothole avoidance mechanisms cannot dynamically adapt in unpredictable environments and do not comfort the traveler well in VANET. This paper proposes a novel Smart Pothole-Avoidance Strategy (SPAS) for safe navigation in a pothole-intensive environment. Potholes are avoided using the Deep Deterministic Policy Gradient (DDPG) algorithm as it performs best in continuous action space tasks and has a faster convergence speed. A Hybrid Recognition Model using the Speech and Gesture mechanism (HRM-SG) is proposed in this paper to collect the traveler’s real-time audio and visual feedback for the DDPG reward function. The received feedback aids in fine-tuning the model to avoid the pothole efficiently than the previous pothole. Traveler’s feedback is coupled with the vehicle’s sensor data and used to decide the time, speed, and angle at which lane change and speed change are executed. Finally, the SPAS continuously optimizes lane change parameters in VANET to achieve maximal traveler comfort during the operation. The result analysis indicates that SPAS achieves a 10-15% improvement in the accuracy of pothole avoidance, 10-12% higher comfort, and 8-10% faster convergence than the existing state-of-the-art techniques.

Mediating Agent Reliability with Human Trust, Situation Awareness, and Performance in Autonomously-Collaborative Human-Agent Teams

When teaming with humans, the reliability of intelligent agents may sporadically change due to failure or environmental constraints. Alternatively, an agent may be more reliable than a human because their performance is less likely to degrade (e.g., due to fatigue). Research often investigates human-agent interactions under little to no time constraints, such as discrete decision-making tasks where the automation is relegated to the role of an assistant. This paper conducts a quantitative investigation towards varying reliability in human-agent teams in a time-pressured continuous pursuit task, and it interconnects individual differences, perceptual factors, and task performance through structural equation modeling. Results indicate that reducing reliability may generate a more effective agent imperceptibly different from a fully reliable agent, while contributing to overall team performance. The mediation analysis shows replication of factors studied in the trust and situation awareness literature while providing new insights: agents with an active stake in the task (i.e., success is dependent on team performance) offset loss of situation awareness, differing from the usual notion of overtrust. We conclude with generalizing implications from an abstract pursuit task, and we highlight challenges when conducting research in time-pressured continuous domains.

The Review of Continuation Task in China

This paper briefly reviews the research on continuation task in China. While summarizing the main research achievements in this field, points out the problems to be further solved, aims to enable people to have a comprehensive understanding of the research status in this field.

An Empirical Research on Schema Theory Based Teaching of the Continuation Task for Chinese Senior High School Students

The continuation task, a novel type of source-based writing task which requires students to read and accomplish an unfinished source text, has gained growing popularity in English writing tests, particularly in China. This study employed schema theory in the teaching of senior high school continuation tasks and delved into its resultant effects on learners’ overall writing ability, lexical richness, syntactic complexity, and semantic coherence. Theoretically, it serves as an extension of the Schema theory, Practically, it contributes to the improvement of the continuation task instruction and offers a realistic method to achieving better writing from the perspectives of linguistic schema, content schema, and formal schema. This research revolves around such questions: What effects do schema theory-based Continuation task instructions have on students’ overall writing competence; lexical richness; syntactic complexity and semantic coherence? During the research, two groups of EFL students (N=110) from Chinese senior high schools participated in the trial for fourteen weeks. One group was randomly selected as Control Class where the teacher adopted traditional teaching approaches. At the same time, the other was set up as the Experimental Class guided by schema theory. The participants writing performance were evaluated through the lexical richness, syntactic complexity and semantic coherence. Sample T-test and paired T-test found statistically significant differences between the Control class and the Experimental class. These findings suggest that the schema theory-based approach, such as providing a semantic map or outlining the story to participants, was proven effective in honing the students’ overall writing capability, lexical richness, syntactic complexity, and semantic coherence. Because of the chosen research approach, its efficacy is limited concerning language and discourse.

Visual continuous recognition reveals behavioral and neural differences for short- and long-term scene memory.

Humans have a remarkably high capacity and long duration memory for complex scenes. Previous research documents the neural substrates that allow for efficient categorization of scenes from other complex stimuli like objects and faces, but the spatiotemporal neural dynamics underlying scene memory at timescales relevant to working and longer-term memory are less well understood. In the present study, we used high density EEG during a visual continuous recognition task in which new, old, and scrambled scenes consisting of color outdoor photographs were presented at an average rate 0.26 Hz. Old scenes were single repeated presentations occurring within either a short-term (< 20 s) or longer-term intervals of between 30 s and 3 min or 4 and 10 min. Overall recognition was far above chance, with better performance at shorter- than longer-term intervals. Sensor-level ANOVA and post hoc pairwise comparisons of event related potentials (ERPs) revealed three main findings: (1) occipital and parietal amplitudes distinguishing new and old from scrambled scenes; (2) frontal amplitudes distinguishing old from new scenes with a central positivity highest for hits compared to misses, false alarms and correct rejections; and (3) frontal and parietal changes from ∼300 to ∼600 ms distinguishing among old scenes previously encountered at short- and longer-term retention intervals. These findings reveal how distributed spatiotemporal neural changes evolve to support short- and longer-term recognition of complex scenes.

Investigation on the effects of presentation modality for spatial signals on human performance using a dual task paradigm

A dual task was designed to involve a tracking mission with various tracking speeds and a spatial compatibility task with various signal-key mappings and presentation modalities. This dual task was used to investigate the effects of workload and resource competition in distinct parts of the dual-task process. The results demonstrated that increasing the tracking speed adversely affected the tracking performance but led to positive arousal to the secondary discrete response task. Visual spatial signals gave the shortest reaction time due to the optimal time-sharing of the visual resources in the focal and ambient channels. Compared with visual spatial signals, spatial signals of auditory and tactile modalities did not lead to an improved performance because of their cross-modality nature. These findings provided practical design guidelines for dual tasks in which the operators need to complete a continuous monitoring task visually and elicit timely and accurate responses to spatial information.

Assessing Japanese junior high school students’ English achievement through computer-based testing in the classroom: a case of integrated reading-into-writing continuous task

IntroductionThis paper describes the exploratory case and initial evaluation of the computer-based testing (CBT) prototype. The advantage of CBT over paper-based testing (PBT) is that it allows us to control the order of questions and provides test takers with continuous tasks capturing their thought processes. Additionally, their response process data such as response time (RT) can be obtained. Taking advantage of these, we created a CBT prototype in the classroom for Japanese junior high school students.Case descriptionA CBT model was created to assess integrated reading and writing ability and was administered to 32 junior high school students. Their process achievement and the relation between the process response and writing quality were analyzed. Students’ RT for each screen was analyzed using hierarchical cluster analysis.Discussion and evaluationWe identified not only students facing difficulties at each stage of a series of thought processes but also five clusters that include students spending too much time reading source texts or organizing their ideas. We suggest how CBT can be developed to identify students with difficulties and applied to teaching.ConclusionsCBT has the possibility of detecting students who are able to complete the language performance task by controlling the order of answers, asking questions sequentially, and obtaining RT effectively.

The neuroelectrophysiological and behavioral effects of transcranial direct current stimulation on executive vigilance under a continuous monotonous condition.

A prolonged period of vigilance task will lead to vigilance decrement and a drop in cognitive efficiency. Although transcranial direct current stimulation (tDCS) can be used to improve cognitive performance following vigilance decrement, the findings in this area of study are inconsistent. This study aims to identify the neuroelectrophysiological and behavioral effects of tDCS over the left dorsolateral prefrontal cortex (DLPFC) on executive vigilance under a continuous monotonous condition. We recruited 29 participants who randomly received 30 min active or sham tDCS before the vigilance task (anode electrode at the left DLPFC, cathode electrode at the right supraorbital area). Participants completed four sessions of vigilance task and five sessions of self-report sleepiness, Oddball task, and Go/Nogo task, for a total of about 5 h. EEG was acquired in real-time throughout the experiment. Repeated measures of ANOVA were utilized to analyze the evolution of each metric with task-on-time. The results demonstrated that subjective arousal state, vigilance performance, event-related potentials (ERPs), and EEG power were significantly affected by time on task. Brain stimulation did not significantly affect the evolution of subjective and objective executive vigilance performance, but significantly modulated spontaneous activity in the alpha and beta bands across the entire brain. The continuous enhancement of the prefrontal cortex increased P2 amplitude for the Oddball task, which was associated with the enhancement of the early stage of information processing. P3 amplitude had a temporary enhancement effect, which significantly decreased following a cognitive fatigue. tDCS had a continuous enhancement effect on N2 amplitude for the Go/Nogo task, which was associated with the enhanced inhibition of distracting stimuli. Together, the current data suggest that anodal tDCS over left DLPFC possibly enhances the early stage of relevant information processing and the inhibitory control of distracting stimuli during a continuous and monotonous vigilance task.

Distraction by violation of sensory predictions: Functional distinction between deviant sounds and unexpected silences

It has been established that participants performing a continuous categorization task respond significantly slower following the presentation of unexpected, task-irrelevant, auditory stimuli, compared to a repetitive (standard) sound. Evidence indicates that such distraction emerges because of the violation of sensory predictions. This has typically been studied by measuring the impact of replacing the repeated sound by a different sound on rare and unpredictable trials. Here, we examine the impact of a different type of violation: the mere omission of the standard sound. Capitalizing upon the recent finding that deviant sounds exert distinct effects on response times as a function of whether participants produced or withheld a response on the previous trial, we present the results of an experiment seeking to disentangle two potential effects of sound omission: deviance distraction and the removal of an unspecific warning signal. The results indicate that deviant sound and the unexpected omission of the standard sound impact response times through, at least partially, distinct mechanisms. Deviant sounds affect performance by triggering the orienting of attention towards a new sensory input. Sound omissions, in contrast, appear to affect performance in part because responses no longer benefit from an unspecific warning signal to prepare for action.

The continuation task and the model-as-feedback writing task in L2 vocabulary learning: Timing of model texts

This study examines the effects of the continuation task and the model-as-feedback writing task (MAFW) on English as a foreign language (EFL) vocabulary learning. Three classes of intermediate-level Chinese EFL learners were randomly assigned to a continuation group, a MAFW group, and a control group. Three aspects of vocabulary knowledge – written form, meaning and form, and grammatical functions – were each assessed by receptive and productive tests. It was found that (1) both tasks led to significant immediate and long-term development of word knowledge of written form, form and meaning, and grammatical functions; and (2) the continuation task showed superiority over the MAFW task in enhancing productive knowledge of written form, and receptive and productive knowledge of form and meaning as well as grammatical functions. Implications of these results for EFL vocabulary teaching are discussed.

An Investigation of the Effects of Brain Fatigue on the Sustained Attention of Intelligent Coal Mine VDT Operators.

Intelligent mines require much more mental effort from visual display terminal (VDT) operators. Long periods of mental effort can easily result in operator fatigue, which further increases the possibility of operation error. Therefore, research into how brain fatigue affects the sustained attention of VDT operators in intelligent mines is important. The research methods were as follows: (1) Recruit 17 intelligent mine VDT operators as subjects. Select objective physiological indicators, such as reaction time, error rate, task duration, flicker fusion frequency, heart rate, electrodermal activity, and blink frequency, and combine these with the subjective Karolinska Sleepiness Scale to build a comprehensive brain fatigue evaluation system. (2) According to the fatigue-inducing experiment requirements, subjects are required to carry out mathematical operations in accordance with the rules during the presentation time, determine whether the results of the operations fall within the [7, 13] interval, and continue for 120 min to induce brain fatigue. (3) Perform the standard stimulus button response experiment of the sustained attention to response task, before and after brain fatigue, and compare each result. The results show that: (1) When the standard stimulus appeared in the EEG experiment, the amplitude of the early N100 component before and after brain fatigue was significantly different. When the bias stimulus appeared, the average amplitudes of the P200 component and the late positive component, before and after brain fatigue, were significantly different, suggesting that the brain fatigue of VDT workers in coal mines would reduce sustained attention; (2) After the 120 min of the continuous operation task, the subjects showed obvious brain fatigue. The objective brain fatigue was followed by an increase in reaction time, an increase in error rate, a decrease in flicker fusion frequency, an increase in heart rate, an increase in electrodermal current, an increase in the number of blinks, and a larger pupil diameter, and both the subjective and objective data indicated more significant changes in the subjects’ brain fatigue at the 45th and 90th min. The results of the study could provide insight into the reduction in operational efficiency and safety of VDT operators in intelligent mines due to brain fatigue and further enrich the research in the area of brain fatigue in VDT operations.

Adult age differences in specific and gist associative episodic memory across short- and long-term retention intervals.

Age-related deficits in associative episodic memory have been widely reported, but recent research suggests that some of these deficits occur for highly specific but not gist representations. It remains undetermined whether older adults' deficits in specific associative episodic memory, observed in long-term memory, are also present in short-term memory. We used a continuous associative recognition task to address this question. Fifty young and 50 older adults studied face-scene pairs, with memory tests occurring in both short-term and long-term memory. Memory tests featured intact (old) pairs, related (similar) pairs, and unrelated (dissimilar) pairs. On short-term memory tests, older adults were less accurate in classifying related pairs, which was manifest by age-related reductions in the probability of retrieving specific memory to engage in recollection rejection. However, older adults were capable of remembering specific details in short-term memory for intact probes but were less likely to remember specific details in long-term memory. Finally, older adults were always as capable as younger adults of remembering gist details. Results suggest that older adults do at least partially encode specific representations in short-term memory, and their access to these specific representations is cue dependent-they can do so when there is a large correspondence between encoding and retrieval conditions but are less likely to engage in deeper elaboration at retrieval. This limits their ability to remember specific details of associations to suppress false recognitions in short-term memory and to engage in veridical recognition in long-term memory. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Memory resources recover gradually over time: The effects of word frequency, presentation rate, and list composition on binding errors and mnemonic precision in source memory.

Normative word frequency has played a key role in the study of human memory, but there is little agreement as to the mechanism responsible for its effects. To determine whether word frequency affects binding probability or memory precision, we used a continuous reproduction task to examine working memory for spatial positions of words. In three experiments, after studying a list of five words, participants had to report the spatial location of one of them on a circle. Across experiments we varied word frequency, presentation rate, and the proportion of low-frequency words on each trial. A mixture model dissociated memory precision, binding failure, and guessing rate parameters from the continuous distribution of errors. On trials that contained only low- or only high-frequency words, low-frequency words led to a greater degree of error in recalling the associated location. This was due to a higher word-location binding failure and not due to differences in memory precision or guessing rates. Slowing down the presentation rate eliminated the word frequency effect by reducing binding failures for low-frequency words. Mixing frequencies in a single trial hurt high-frequency and helped low-frequency words. These findings support the idea that word frequency can lead to both positive and negative mnemonic effects depending on a trade-off between an HF encoding advantage and a LF retrieval cue advantage. We suggest that (1) low-frequency words require more resources for binding, (2) that these resources recover gradually over time, and that (3) binding fails when these resources are insufficient. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Error controlled actor-critic

The approximation inaccuracy of the value function in reinforcement learning (RL) algorithms unavoidably leads to an overestimation phenomenon, which has negative effects on the convergence of the algorithms. To limit the negative effects of the approximation error, we propose error controlled actor-critic (ECAC) which ensures the approximation error is limited within the value function. We present an investigation of how approximation inaccuracy can impair the optimization process of actor-critic approaches. In addition, we derive an upper bound for the approximation error of the Q function approximator and discover that the error can be reduced by limiting the KL- divergence between every two consecutive policies during policy training. Experiments on a variety of continuous control tasks demonstrate that the proposed actor-critic approach decreases approximation error and outperforms previous model-free RL algorithms by a significant margin.

Deficient Novelty Detection and Encoding in Early Alzheimer’s Disease: An ERP Study

Patients with early Alzheimer’s disease (AD) have difficulty in learning new information and in detecting novel stimuli. The underlying physiological mechanisms are not well known. We investigated the electrophysiological correlates of the early (< 400 ms), automatic phase of novelty detection and encoding in AD. We used high-density EEG Queryin patients with early AD and healthy age-matched controls who performed a continuous recognition task (CRT) involving new stimuli (New), thought to provoke novelty detection and encoding, which were then repeated up to 4 consecutive times to produce over-familiarity with the stimuli. Stimuli then reappeared after 9–15 intervening items (N-back) to be re-encoded. AD patients had substantial difficulty in detecting novel stimuli and recognizing repeated ones. Main evoked potential differences between repeated and new stimuli emerged at 180–260 ms: neural source estimations in controls revealed more extended MTL activation for N-back stimuli and anterior temporal lobe activations for New stimuli compared to highly familiar repetitions. In contrast, AD patients exhibited no activation differences between the three stimulus types. In direct comparison, healthy subjects had significantly stronger MTL activation in response to New and N-back stimuli than AD patients. These results point to abnormally weak early MTL activity as a correlate of deficient novelty detection and encoding in early AD.

Soluble guanylate cyclase stimulator riociguat improves spatial memory in mice via peripheral mechanisms

Soluble guanylate cyclase (sGC) - cyclic guanosine monophosphate (cGMP) signalling is important for healthy memory function and a healthy vascular system. Targeting sGC-cGMP signalling can therefore be a potential strategy to enhance memory processes. sGC can be targeted by using agonists, such as sGC stimulator riociguat. Therefore, this study aimed to target sGC using riociguat to investigate its acute effects on memory function and neuronal plasticity in mice. The effects of riociguat on long-term memory and a biperiden-induced memory deficit model for assessing short-term memory were tested in the object location task, and working memory was tested in the Y-maze continuous alternation task. Pharmacokinetic measurements were performed within brain tissue of mice, and hippocampal plasticity measures were assessed using western blotting. Acute oral administration with a low dose of 0.03 mg/kg riociguat was able to enhance working-, short-, and long-term spatial memory. Under cerebral vasoconstriction higher doses of riociguat were still effective on memory. Pharmacokinetic measurements revealed poor brain penetration of riociguat and its metabolite M−1. Increased activation of VASP was found, while no effects were found on other memory-related hippocampal plasticity measures. Memory enhancing effects of riociguat are most likely regulated by vascular peripheral effects on cGMP signalling. Yet, further research is needed to investigate the possible contribution of hemodynamic or metabolic effects of sGC stimulators on memory performance.

Multi-Task Learning Based on Stochastic Configuration Neural Networks.

When the human brain learns multiple related or continuous tasks, it will produce knowledge sharing and transfer. Thus, fast and effective task learning can be realized. This idea leads to multi-task learning. The key of multi-task learning is to find the correlation between tasks and establish a fast and effective model based on these relationship information. This paper proposes a multi-task learning framework based on stochastic configuration neural networks. It organically combines the idea of the classical parameter sharing multi-task learning with that of constraint sharing configuration in stochastic configuration neural networks. Moreover, it provides an efficient multi-kernel function selection mechanism. The convergence of the proposed algorithm is proved theoretically. The experiment results on one simulation data set and four real life data sets verify the effectiveness of the proposed algorithm.