视觉追踪作业心理负荷的多变量评估研究

敏感性是心理负荷测量技术可靠性的基本要求。该研究利用主任务绩效、次任务绩效、主观“加权负荷”评定和心率变异变化率四项指标,在计算机模拟情境下对视觉追踪作业心理负荷进行多变量评估实验。结果发现,以上述四项指标为基础建立的“综合加权评估指数”是一项较有效的评估指标,其敏感性远高于任何单独的评定。     

心理负荷多种评价指标的比较

本研究通过两个实验,分别对被试从事监控任务和追踪任务时的心理负荷进行测量,从而考察了几种测量指标的变化规律,结果发现,把主观任务难度作为联系两个不同任务的因子,对两个任务各心理负荷测量作综合分析,多数指标变化随负荷程度呈有规律的趋势。(1)主任务测量评价主任务是否超负荷较为有效,而对于非超负荷任务的负荷变化,辅助作业测量较为敏感。(2)心率和血压变化与心理负荷呈近似倒 U 型关系。A 型行为模式个体的心率变化与别的个体的心率变化存在着实质性的模式差异。     

负荷水平和作业信息输入输出形式对视觉追踪操作心理负荷评估敏感性的影响

就负荷水平和信息输入形式、输出形式对视觉追踪作业心理负荷评估指标敏感性的影响进行了实验．获得以下主要结果：①主任务绩效具有较好的评估敏感性;②作业信息输入形式、输出形式对评估指标敏感性有显著影响．     

负荷水平和作业信息输入输出形式对视觉追踪操作心理负荷评估敏感性的影响

就负荷水平和信息输入形式,输出形式对视觉追踪作业心理负荷评估指标敏感性的影响进行了实验,获得以下主要结果：（１）主任务绩效具有较好的评估敏感性;（２）作业信息输入形式、输出形式对评估指标敏感性有显著影响。     

人机交互过程中认知负荷的综合测评方法

设计模拟网络引擎搜索和心算双任务实验,分析主观评定、绩效测量和生理测量三类评估指标对认知负荷变化的敏感性;采用因素分析、BP神经网络和自组织神经网络三种建模方法,探索人机交互过程中认知负荷的综合评估建模方法。结果显示：心理努力、任务主观难度、注视时间、注视次数、主任务反应时、主任务正确率6个指标对认知负荷变化敏感;采用多维综合评估模型对双任务作业认知负荷进行测量总体上比采用单一评估指标的测量更为有效。BP网络和自组织神经网络两种神经网络模型对认知负荷的测量结果优于传统的因素分析方法     

人机交互过程中认知负何的综合测评方法

设计模拟网络引擎搜索和心算双任务实验,分析主观评定、绩效测量和生理测量三类评估指标对认知负荷变化的敏感性;采用因素分析、BP神经网络和自组织神经网络三种建模方法,探索人机交互过程中认知负荷的综合评估建模方法.结果显示:心理努力、任务主观难度、注视时间、注视次数、主任务反应时、主任务正确率6个指标对认知负荷变化敏感;采用多维综合评估模型对双任务作业认知负荷进行测量总体上比采用单一评估指标的测量更为有效.BP网络和自组织神经网络两种神经网络模型对认知负荷的测量结果优于传统的因素分析方法.     

人机交互中认知负荷变化预测模型的构建

设计模拟的人机交互实验, 分析持续作业过程中认知负荷在评估指标上的变化; 采用Elman神经网络和BP神经网络二种建模方法, 探索人机交互过程中认知负荷变化预测建模的构建方法。结果显示：持续作业中认知负荷在主任务反应时、主任务正确率、注视时间、注视次数4个评估指标上变化显著; 在心理努力、任务主观难度2个评估指标上变化不显著; Elman神经网络和BP神经网络两种预测模型可以对不同作业时间段认知负荷在评估指标上发生的变化进行预测; 再结合认知负荷的综合评估模型, 可实现对不同作业时间段个体认知负荷水平等级进行分析。     

虚拟学习环境下图形加工的认知负荷研究

基于单探测变化觉察和双任务范式,采用项目数量（3）×呈现时间（2）×文字线索（2）混合实验设计,对沉浸式虚拟学习环境图形加工特征和认知负荷进行探讨,以任务绩效法与主观测量法评定认知负荷。44名大学生的实验结果显示：（1）项目数量对虚拟空间图形识记主任务绩效和主观认知负荷有显著影响,项目数量越多,主任务正确率越低,反应时越长,主观评定认知负荷越高,同时加工刺激数量以4个为宜;（2）呈现时间对虚拟空间图形识记次任务绩效有显著影响,呈现时间越长,次任务正确率越高,呈现时间超过0.5s有利于次任务加工;（3）文字线索对虚拟图形识记认知负荷有显著影响,重复性文字线索会增加认知负荷。结果表明,在沉浸式虚拟环境中,图形加工的认知负荷特点与平面和三维图形基本一致,项目数量多、呈现时间短以及有重复性文字线索时,认知负荷更高;任务绩效和主观测量评定指标在反映认知负荷强度上不完全一致。     

不同的第二任务在心理负荷测量中敏感性的比较

这是一项关于操作人员的心理负荷测量的实验研究。目的是为了确定哪一种第二任务的方法对测量心理负荷更灵敏。实验以追踪活动为第一任务,以心算、回忆随机数、对偶联想为第二任务。用第二任务操作水平的变化来测定不同难度的第一任务。结果表明,心算比回忆随机数、对偶联想更灵敏。     

认知负荷主观评价量表比较

运用双任务实验范式,比较了三种认知负荷主观评价量表的灵敏度与效度。结果发现：在本研究任务条件下,次任务反应时的稳定性、抗干扰性较好,可以作为认知负荷主观评价的标尺;WP量表与PAAS量表的敏感性均较好,其中WP量表的敏感性、诊断性高于后者,TLX量表的敏感性较弱;WP量表与PAAS量表的效度较好,且好于TLX量表。综合各项指标,在中低难度任务下,WP量表是目前认知负荷较为理想的测量工具。     

Mental workload and visual impairment: differences between pupil, blink, and subjective rating

This research has two aims: (a) To study the concurrent validity of three measures of mental workload, NASA TLX rating scale, pupil dilation and blink rate, testing the hypothesis that they will provide convergent results using a single-task, and dissociative results for dual-task; and (b) To analyse their capability to predict visual search impairment. These three measures were analyzed in the same cognitive tasks in single-task and dual-task (cognitive task and visual search) conditions in a within-subjects experiment with twenty-nine participants. Mental workload measures showed concurrent validity under single-task condition, but a complex pattern of results arose in the dual-task condition: it is suggested that NASA TLX would be a subjective addition of the rating of each task; pupil dilation would measure the average arousal underlying the cognitive tasks; and the blink rate would produce opposite effects: whereas mental workload of cognitive tasks would increase blink rate, visual demand would inhibit it. All three measures were good predictors of visual impairment. The soundness of these measures is discussed with regard to the applied field of driving and other activities.     

The use of Tholos software for combining measures of mental workload: Toward theoretical and methodological improvements

Mental workload is a concept central to a range of disciplines (including cognitive psychology and ergonomics) that has given rise to various theoretical and methodological debates. As a result, researchers have used a number of techniques for measuring mental workload. Traditionally, three categories of measurement technique have been recognized: performance measures (e.g., the dual-task paradigm), subjective measures (e.g., rating scales), and physiological measures (e.g., heart, respiration, and blink rates). Each technique has advantages and limitations; however, some limitations may prevent an accurate evaluation of the mental workload. In this article, we focus on the benefits of combining multiple measures of mental workload. However, because combining several techniques is a very complex process, we have developed the Tholos software in an attempt to reduce this complexity. This software package uses measures from each of the three categories: a dual-task paradigm with auditory signals; the National Aeronautics and Space Administration task load index (NASA-TLX) scale and its simplified version, the “raw” task load index (RTLX); and physiological (such as pupil-dilation) measurements with which our software can merge results from the dual-task paradigm. To illustrate the benefits of using Tholos, we describe a puzzle-solving experiment in which we combined multiple measures of mental workload. The results indicate the importance of combining multiple measures to build upon the theoretical and methodological foundations of mental workload.     

Role of multiple resources in predicting time-sharing efficiency: evaluation of three workload models in a multiple-task setting

The goal of our study was to assess the validity of the assumptions underlying three prominent workload models: the Time-Line Analysis and Prediction workload model (Parks & Boucek, 1989), the VACP workload model (Aldrich, Szabo, & Bierbaum, 1989), and the W/INDEX model (North & Riley, 1989). Sixteen subjects flew a low-fidelity flight simulation. Subjects were required to perform a two-axis tracking task, a concurrent visual-monitoring task, and a discrete decision task. The decision task had 16 variations defined by two levels on each of the following dimensions: input modality (visual vs. auditory), processing code (spatial vs. verbal), difficulty (easy vs. hard), and response modality (manual vs. voice). Dual-task costs were found only for the tracking task. The tracking data were then analyzed using two approaches: a traditional analysis of variance (ANOVA) and a correlational analysis of tracking performance versus model predictions. The ANOVA revealed that performance on the tracking task was better when the concurrent decision task was responded to vocally and was easy. Input modality and processing code of the concurrent decision task had no significant effect on tracking performance. The correlational analysis was used to evaluate each of the three models, to determine what features were responsible for improving the models' fit, and to compare their performance with a pure time-line model that makes no multiple-resource assumptions. All three models did a good job of predicting variance between experimental conditions, accounting for between 56% and 84% of the variance in our data and between 10% and 40% of an earlier data set. Different features of each model that affect the fit are then discussed. We conclude that it is important for models to retain a multiple-resource coding, although the best features of that coding remain to be determined. Coding tasks by their demand level appears to be less critical.     

Comparing eye-tracking metrics of mental workload caused by NDRTs in semi-autonomous driving

The objective of this study was to verify the effectiveness of eye-tacking metrics in indicating driver’s mental workload in semi-autonomous driving when the driver is engaged in different non-driving related tasks (NDRTs). A driving simulator was developed for three scenarios (high-, medium-, and low-mental workload presented by SAE (Society of Automotive Engineers) Levels 0, 1, and 2) and three uni-modality secondary tasks. Thirty-six individuals participated in the driving simulation experiment. NASA-TLX (Task Load Index), secondary task performance, and eye-tracking metrics were used as indicators of mental workload. The subjective rating using the NASA-TLX showed a main effect of autonomous level on mental workload in both visual and auditory tasks. Correlation-matrix calculation and principal-component extraction indicated that pupil diameter change, number of saccades, saccade duration, fixation duration, and 3D gaze entropy were effective indicators of a driver’s mental workload in the visual and auditory multi-tasking situations of semi-autonomous driving. The accuracy of predicting the mental-workload level using the K-Nearest Neighbor (KNN) classifier was 88.9% with bootstrapped data. These results can be used to develop an adaptive multi-modal interface that issues efficient and safe takeover requests.     

Effects of mental workload and caffeine on catecholamines and blood pressure compared to performance variations

Caffeine is characterised as a central nervous system stimulant, also affecting metabolic and cardiovascular functions. A number of studies have demonstrated an effect of caffeine on the excretion of catecholamines and their metabolites. Urinary epinephrine and norepinephrine have been shown to increase after caffeine administration. Similar trends were observed in our study in adrenaline (ADR) and noradrenaline (NORADR) levels and additionally a dose dependent effect of caffeine. The effect of caffeine on cognitive performance, blood pressure, and catecholamines was tested under resting conditions and under mental workload. Each subject performed the test after oral administration of 1 cup and then 3 cups of coffee. Root mean square error (RMSE) for the tracking task was continuously monitored. Blood pressure was also recorded before and after each stage of the experiment. Catecholamines were collected and measured for three different conditions as: at rest, after mental stress alone, after one dose of caffeine under stress, and after triple dose of caffeine under stress. Comparison of the performance of each stage with the resting conditions revealed statistically significant differences between group of smokers/coffee drinkers compared with the other two groups of non-coffee drinkers/non-smokers and non-smokers/coffee drinkers. There was no statistically significant difference between the last two groups. There was an increase of urine adrenaline with 1 cup of coffee and statistically significant increase of urine noradrenaline. Both catecholamines were significantly increased with triple dose of caffeine. Mental workload increased catecholamines. There was a dose dependent effect of caffeine on catecholamines.     

Evaluation of meditation and relaxation on physiological response during the performance of fine motor and gross motor tasks

This study investigated the effects of meditation/relaxation on physiological responses during the performance of a fine motor and a gross motor task. A pretest-posttest control group, randomized-blocks design was used to study a group of 16 meditators and a group of 16 nonmeditators, subgroups of each who relaxed prior to performing on a pursuit-rotor tracking device as a fine motor task and to performing the Luft cycle ergometer protocol to a heart rate of 70% of age-adjusted maximum heart rate as a gross motor task. During each of these tasks heart rate, systolic blood pressure, rate-pressure-product, and EMG activity of the frontalis muscle were monitored. No significant difference in the performance of either the fine motor or the gross motor task was noted for persons practicing meditation and persons who were nonmeditators but were given the opportunity to relax prior to a motor task. Likewise, no significant difference was noted in the pattern of response to the imposed fine motor or gross motor task by meditators or relaxed nonmeditators.     

人在多项任务中的业绩及脑力负荷

在超脑力负荷状态下人的业绩是如何变化的？在实验中,让被试者同时完成四项内容不同的任务,即补偿追踪,选择反应,模拟雷达观察和算术运算。脑力负荷的强度是由改变工作的快慢节奏来实现的。实验的数据表明,随着脑力负荷的增加,人的业绩是逐渐下降的。在面对超负荷的多项任务时,人的信息处理过程更像一个单通道系统,集中精力完成某一工作,然后迅速地转移到下一个工作。     

Eye movement indices of mental workload

Four investigations were carried out to assess the feasibility of using eye movement measures as indices of mental workload. In the first experiment, saccadic extent was measured during free viewing while subjects performed low, moderate and high complexity, auditory tone counting as the workload tasks. The range of saccadic extent decreased significantly as tone counting complexity (workload) was increased. In the second experiment the range of spontaneous saccades was measured under three levels of counting complexity with a visual task that did not require fixation or tracking. The results indicated that the extent of saccadic eye movements was significantly restricted as counting complexity increased. In the third experiment, the effects of practice were examined and decreased saccadic range under high tone counting complexity was observed even when significant increases in performance occurred with practice. Finally, in experiment 4, the first experiment was repeated with additional optokinetic stimulation and the saccadic range was again observed to decrease with tone counting complexity. The results indicated that the extent of spontaneous and elicited eye movements was significantly restricted as counting complexity increased. We conclude that this measure may provide a valuable index of mental workload.