Abstract
Background: The present study aimed to evaluate the operators’ mental workload (MW) of cement, city traffic control and power plant control centers using subjective and objective measures during system vital parameters monitoring. Methods: This cross-sectional study was conducted from June 2014 to February 2015 at the cement, city traffic control and power plant control centers. Electrocardiography and electroencephalography data were recorded from forty males during performing their daily working in resting, low mental workload (LMW), high mental workload (HMW) and recovery conditions (each block 5 minutes). The NASA-Task Load Index (TLX) was used to evaluate the subjective workload of the operators. Results: The results showed that increasing MW had a significant effect on the operators subjective responses in two conditions ([1,53] = 216.303, P < 0.001, η2 = 0.803). Also,the Task-MW interaction effect on operators subjective responses was significant (F [3, 53] = 12.628,P < 0.001, η2 = 0.417). Analysis of repeated measures analysis of variance (ANOVA) indicated that increasing mental demands had a significant effect on heart rate, low frequency/high frequency ratio, theta and alpha band activity. Conclusion: The results suggested that when operators’ mental demands especially in traffic control and power plant tasks increased, their mental fatigue and stress level increased and their mental health deteriorated. Therefore, it may be necessary to implement an ergonomic program or administrative control to manage mental probably health in these control centers. Furthermore, by evaluating MW, the control center director can organize the human resources for each MW condition to sustain the appropriate performance as well as improve system functions.
Highlights
The concept of mental workload (MW) has become an important issue for all kinds of industry since1960s.1 Many ergonomists or researchers have applied subjective and physiological measures to evaluate MW quantitatively.[2,3,4] Subjective rating scales, as an important tool, are used to evaluate MW of system operators.[5] de Winter[6] has explained that the most frequently used subjective rating scales are the NASA-Task Load Index (TLX).[7]
A repeated measures analysis of variance (ANOVA) revealed that increasing MW had a significant effect on the operators’ subjective responses in low mental workload (LMW) compared to HMWF ([1,53] = 216.303, P < 0.001, ε η2 = 0.803)
Our experiment showed that working in high mental workload (HMW) condition led to an increase in both subjective and some physiological responses such as HR, Low Frequency over the High Frequency (LF/HF) ratio, and theta and alpha band
Summary
The concept of mental workload (MW) has become an important issue for all kinds of industry since1960s.1 Many ergonomists or researchers have applied subjective and physiological measures to evaluate MW quantitatively.[2,3,4] Subjective rating scales, as an important tool, are used to evaluate MW of system operators.[5] de Winter[6] has explained that the most frequently used subjective rating scales are the NASA-Task Load Index (TLX).[7]. Many ergonomists or researchers have applied subjective and physiological measures to evaluate MW quantitatively.[2,3,4] Subjective rating scales, as an important tool, are used to evaluate MW of system operators.[5] de Winter[6] has explained that the most frequently used subjective rating scales are the NASA-Task Load Index (TLX).[7] Psychophysiological measures allow a more objective workload assessment and can provide “real time” evaluation.[8] Heart rate or heart rate variability (HRV) collected from an electrocardiogram (ECG) is widely used to evaluate MW9,10 and recording of signal is noninvasive and safe; it causes no injuries or pain to humans.[11] most studies apply information from the frequency bands of the EEG to analyze MW and fatigue.[12] MW will lead to changes of EEG components: alpha band, beta band, theta band, and delta band.[13] EEG signals can be acquired outside of specialized laboratory environments, because of the compactness of the associated technology.[3] Human operators are a vital component of systems to Fallahi et al maintain their performance at an appropriate level They have been commonly found in controlling workplaces for many years.[14] van Daalen et al[15] indicated that mismatch between MW and capabilities of worker can cause work-related stress. By evaluating MW, the control center director can organize the human resources for each MW condition to sustain the appropriate performance as well as improve system functions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
