Title: Investigating the effect of indoor thermal environment on occupants’ mental workload and task performance using electroencephalogram
Workers' performance in indoor offices can be greatly affected by the thermal condition of the environment. However, this effect can be difficult to quantify, especially when the thermal stress is a moderate increase or decrease in temperature and the work productivity cannot be directly measured. Subjects' high motivation to perform well under experimental conditions also causes difficulties in comparing their performance in different thermal environments. In order to overcome these limitations, this paper proposes a method to investigate the
effect of the indoor thermal conditions on occupants' performance by studying occupants' mental workload measured by the electroencephalography (EEG) when they perform standardized cognitive tasks. An experiment integrating EEG mental workload measurement and cognitive tasks was implemented on 15 subjects. EEG data were collected while subjects were performing four cognitive tasks on computers. Based on previous studies, we
propose a mental workload index calculated from the frontal theta and parietal alpha frequency band power. Within-subject comparisons were performed to investigate whether subjects' mental workload is statistically different under three different thermal environments, representing thermal sensations of slightly cool, neutral, and slightly warm. The results show that the effect of thermal environment varies across different individuals. By comparing the mental workload index among different thermal environments, we found that the slightly warm
environment resulted in a relatively higher mental workload than the other two environments to achieve the same performance. The study provides promising insights into how the thermal environment influences occupants’ performance by affecting their mental workload from the neurophysiological perspective. more »« less
Wang, Xi; Li, Da; Menassa, Carol; Kamat, Vineet.(
, UrbSys'19: Proceedings of the 1st ACM International Workshop on Urban Building Energy Sensing, Controls, Big Data Analysis, and Visualization)
null
(Ed.)
Mental workload represents the mental resources an individual devotes to a task. In a building environment, understanding how ambient thermal conditions affect occupants' mental workload offers an opportunity to achieve optimal thermal settings for the heating, ventilation, and air conditioning (HVAC) systems. However, directly measuring mental workload on a large and continuous scale requires occupants to perform subjective tests or wear electroencephalogram (EEG) or similar devices, which is impractical. This paper assesses the feasibility of using infrared facial thermography captured by a low-cost thermal camera to disclose mental workload. An experiment was conducted to measure the facial skin temperature while subjects performed cognitive tasks in three different thermal environments, representing occupants' thermal sensation of slightly cool, neutral, and slightly warm. Mental workload was measured using an EEG headset to eliminate subjective bias. The correlations between facial temperature and mental workload vary with different individuals and thermal conditions. Relatively strong correlations are found in the neutral environment and in the regions of ears, mouth, and neck. The results also suggest that future work should collect data under extended experiment duration. This is because it was observed that the response of facial skin temperature to mental workload varies with task type; thus, increasing the repetitiveness for each type of task or using more challenging tasks in the experiment could potentially lead to more insights on this relationship.
Wang, Xi; Li, Da; Menassa, Carol. C; and Kamat, Vineet R.(
, International Conference on. Computing in Civil Engineering (i3CE): Smart Cities, Sustainability, and Resilience)
The thermal environment has a great influence on individuals’ performance; however, factors
such as one’s motivation to perform well under experimental conditions cause difficulties in
assessing how room temperature affect subjects’ performance. One approach to overcome this problem is to understand the changes in individuals’ neurophysiological conditions. This paper reports on the results of an experiment where electroencephalogram (EEG) data were collected from 5 subjects while they performed four computerized cognitive tasks. Power spectral density of EEG signals in three different thermal environments, slightly cool, neutral, and slightly warm, was compared within subjects. In most cases, significant differences in PSD of the frontal theta (4–8 Hz) activity are observed, indicating individuals’ mental effort varies with room temperature. In the long run, the increased mental workload will reduce individuals’ performance and be detrimental to their productivity. The study indicates that the proposed method could be implemented on a larger scale for further studies.
Hurley, Rachel; Belyamani, Mohamed; Djamasbi, Soussan; Somasse, Gbetonmasse; Strauss, Sarah; Liu, Shichao(
, The 5th International Conference on Building Energy & Environment (COBEE))
The purpose of this study is to investigate the combined impact of mask-wearing on cognitive performance and risk-taking behaviors. Participants were divided into a control group (N=24) without and an experimental group (N=27) with a surgical mask. Both groups completed the tasks in a warm environment (30 oC) where the conditions can reduce cognition and decision-making as well. These conditions are common in indoor spaces without sufficient air conditioning during a heat wave. Cognition and risk-taking behaviors were assessed using computerized tests. Results showed that mask-wearing in warm environment did not negatively impact cognitive performance, nor did it increase risk-taking behavior as the concept of risk compensation predicts, even when the CO2 concentration was elevated to approximately 29,000 ppm on average inside the mask. On the contrary, mask-wearing participants showed less risk-taking behaviors, slightly better response inhibition and better short-term memory. These results do not support previous findings suggesting that even a moderately increased indoor CO2 level can reduce cognition. We hypothesize that human adaptation effects (due to mask-wearing on a daily basis) make people less vulnerable to the adverse environment (i.e., excessive air temperature and CO2 levels), which will be investigated in the future studies.
Devlin, Shannon Patricia; Moacdieh, Nadine Marie; Wickens, Christopher D.; Riggs, Sara Lu(
, IISE Transactions on Occupational Ergonomics and Human Factors)
Complex and dynamic environments including military operations, healthcare, aviation, and driving require operators to transition seamlessly between levels of mental workload. However, little is known about how the rate of an increase in workload impacts multitasking performance, especially in the context of real-world tasks. We evaluated both gradual and sudden workload increases in the dynamic multitasking environment of an Unmanned Aerial Vehicle (UAV) command and control testbed and compared them to constant workload. Workload transitions were found to improve response time and accuracy compared to when workload was held constant at low or high. These results suggest that workload transitions may allow operators to better regulate mental resources. These findings can also inform the design of operations and technology to assist operators’ management of cognitive resources, which include negating the adverse effects of vigilance decrements during low workload periods and data overload during high workload periods.
Background: High workload and workload transitions can affect performance; however, it is not clear how the rate of transition from low to high workload influences performance in a multitasking setting.
Purpose: We investigated the effect of workload transition rate on performance in a multitasking environment that is akin to the expectations of operators in complex, data-rich work domains.
Method: An Unmanned Aerial Vehicle (UAV) command and control testbed was used to vary workload between low, high, gradually transitioning from low to high, and suddenly transitioning from low to high. Performance measures consisted of the response time and accuracy of one primary task and three secondary tasks. Analyses compared: (a) performance differences between gradual and sudden increases in workload; (b) performance during the low workload phases of the workload transitions; and (c) performance during the high workload phases of the workload transitions.
Results: Overall, there were limited performance differences between gradual and sudden workload transitions. However, both types of transitions led to better performance than constant workload, lending some support for the effort regulation explanation which suggests that participants actively evaluated the amount of mental resources necessary to successfully complete a task after a workload transition.
Conclusions: Gradual and sudden workload transitions benefit primary and secondary task performance, suggesting that the applicability of existing theoretical explanations depend on the context. For example, varying task demands can be a means to assist operators in the appropriate regulation of mental resources in domains with interdependent tasks. These findings can inform occupation and technology design to support task management.
de Oliveira Faria, Nayara; Kandil, Dina; Gabbard, Joseph L.(
, Proceedings of the Human Factors and Ergonomics Society Annual Meeting)
Background: Drivers gather most of the information they need to drive by looking at the world around them and at visual displays within the vehicle. Navigation systems automate the way drivers navigate. In using these systems, drivers offload both tactical (route following) and strategic aspects (route planning) of navigational tasks to the automated SatNav system, freeing up cognitive and attentional resources that can be used in other tasks (Burnett, 2009). Despite the potential benefits and opportunities that navigation systems provide, their use can also be problematic. For example, research suggests that drivers using SatNav do not develop as much environmental spatial knowledge as drivers using paper maps (Waters & Winter, 2011; Parush, Ahuvia, & Erev, 2007). With recent growth and advances of augmented reality (AR) head-up displays (HUDs), there are new opportunities to display navigation information directly within a driver’s forward field of view, allowing them to gather information needed to navigate without looking away from the road. While the technology is promising, the nuances of interface design and its impacts on drivers must be further understood before AR can be widely and safely incorporated into vehicles. Specifically, an impact that warrants investigation is the role of AR HUDS in spatial knowledge acquisition while driving. Acquiring high levels of spatial knowledge is crucial for navigation tasks because individuals who have greater levels of spatial knowledge acquisition are more capable of navigating based on their own internal knowledge (Bolton, Burnett, & Large, 2015). Moreover, the ability to develop an accurate and comprehensive cognitive map acts as a social function in which individuals are able to navigate for others, provide verbal directions and sketch direction maps (Hill, 1987). Given these points, the relationship between spatial knowledge acquisition and novel technologies such as AR HUDs in driving is a relevant topic for investigation. Objectives: This work explored whether providing conformal AR navigational cues improves spatial knowledge acquisition (as compared to traditional HUD visual cues) to assess the plausibility and justification for investment in generating larger FOV AR HUDs with potentially multiple focal planes. Methods: This study employed a 2x2 between-subjects design in which twenty-four participants were counterbalanced by gender. We used a fixed base, medium fidelity driving simulator for where participants drove while navigating with one of two possible HUD interface designs: a world-relative arrow post sign and a screen-relative traditional arrow. During the 10-15 minute drive, participants drove the route and were encouraged to verbally share feedback as they proceeded. After the drive, participants completed a NASA-TLX questionnaire to record their perceived workload. We measured spatial knowledge at two levels: landmark and route knowledge. Landmark knowledge was assessed using an iconic recognition task, while route knowledge was assessed using a scene ordering task. After completion of the study, individuals signed a post-trial consent form and were compensated $10 for their time. Results: NASA-TLX performance subscale ratings revealed that participants felt that they performed better during the world-relative condition but at a higher rate of perceived workload. However, in terms of perceived workload, results suggest there is no significant difference between interface design conditions. Landmark knowledge results suggest that the mean number of remembered scenes among both conditions is statistically similar, indicating participants using both interface designs remembered the same proportion of on-route scenes. Deviance analysis show that only maneuver direction had an influence on landmark knowledge testing performance. Route knowledge results suggest that the proportion of scenes on-route which were correctly sequenced by participants is similar under both conditions. Finally, participants exhibited poorer performance in the route knowledge task as compared to landmark knowledge task (independent of HUD interface design). Conclusions: This study described a driving simulator study which evaluated the head-up provision of two types of AR navigation interface designs. The world-relative condition placed an artificial post sign at the corner of an approaching intersection containing a real landmark. The screen-relative condition displayed turn directions using a screen-fixed traditional arrow located directly ahead of the participant on the right or left side on the HUD. Overall results of this initial study provide evidence that the use of both screen-relative and world-relative AR head-up display interfaces have similar impact on spatial knowledge acquisition and perceived workload while driving. These results contrast a common perspective in the AR community that conformal, world-relative graphics are inherently more effective. This study instead suggests that simple, screen-fixed designs may indeed be effective in certain contexts.
Wang, Xi, Li, Da, Menassa, Carol. C, and and Kamat, Vineet R. Investigating the effect of indoor thermal environment on occupants’ mental workload and task performance using electroencephalogram. Retrieved from https://par.nsf.gov/biblio/10110475. Building and environment .158
Wang, Xi, Li, Da, Menassa, Carol. C, & and Kamat, Vineet R. Investigating the effect of indoor thermal environment on occupants’ mental workload and task performance using electroencephalogram. Building and environment, (158). Retrieved from https://par.nsf.gov/biblio/10110475.
Wang, Xi, Li, Da, Menassa, Carol. C, and and Kamat, Vineet R.
"Investigating the effect of indoor thermal environment on occupants’ mental workload and task performance using electroencephalogram". Building and environment (158). Country unknown/Code not available. https://par.nsf.gov/biblio/10110475.
@article{osti_10110475,
place = {Country unknown/Code not available},
title = {Investigating the effect of indoor thermal environment on occupants’ mental workload and task performance using electroencephalogram},
url = {https://par.nsf.gov/biblio/10110475},
abstractNote = {Workers' performance in indoor offices can be greatly affected by the thermal condition of the environment. However, this effect can be difficult to quantify, especially when the thermal stress is a moderate increase or decrease in temperature and the work productivity cannot be directly measured. Subjects' high motivation to perform well under experimental conditions also causes difficulties in comparing their performance in different thermal environments. In order to overcome these limitations, this paper proposes a method to investigate the effect of the indoor thermal conditions on occupants' performance by studying occupants' mental workload measured by the electroencephalography (EEG) when they perform standardized cognitive tasks. An experiment integrating EEG mental workload measurement and cognitive tasks was implemented on 15 subjects. EEG data were collected while subjects were performing four cognitive tasks on computers. Based on previous studies, we propose a mental workload index calculated from the frontal theta and parietal alpha frequency band power. Within-subject comparisons were performed to investigate whether subjects' mental workload is statistically different under three different thermal environments, representing thermal sensations of slightly cool, neutral, and slightly warm. The results show that the effect of thermal environment varies across different individuals. By comparing the mental workload index among different thermal environments, we found that the slightly warm environment resulted in a relatively higher mental workload than the other two environments to achieve the same performance. The study provides promising insights into how the thermal environment influences occupants’ performance by affecting their mental workload from the neurophysiological perspective.},
journal = {Building and environment},
number = {158},
author = {Wang, Xi and Li, Da and Menassa, Carol. C and and Kamat, Vineet R.},
}
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