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The Impact of Mental Workload Levels on Physiological and Subjective Responses
Majid Fallahi, Majid Motamedzade, Zahra Sharifi, Rashid Heidari Moghaddam, Alireza Soltanian,
Volume 4, Issue 3 (12-2016)
Abstract

Introduction: Advances in technology and the use of complex systems at work have imposed high mental workloads to operators; so, continuous monitoring of mental workload can help to prevent mental problems and maintain mental health. Therefore, this study aimed to investigate the impact of mental workload on physiological and subjective responses.

Methods: This cross-sectional descriptive-analytical study was performed on 16 healthy university students in 2014 at a laboratory setting. Physiological parameters of surface electromyography and electrocardiography in six blocks (resting, high mental work, moderate, low, very low and recovery) were measured using NeXus-4. After performing each block, the NASA-TLX questionnaire was completed. Statistical analysis was conducted using SPSS software version 21.0. A 5% significance level was adopted in all the tests.

Results: The results showed significant differences for the average score of NASA-TLX between the different levels of mental work load (P < 0.05). Also, the analysis of repeated measures variance showed significant differences for heart rate and heart rate variability parameters in the six blocks (P < 0.05), but no significant difference was observed for the shoulder muscles activity.

Conclusions: Different levels of mental work load can impact on people's subjective responses and some of their physiological responses. Thus, in such workplaces, it will be necessary to conduct an ergonomic program to manage mental health.


Creating a Numerical Index for Measurement of Workload Levels in the Simulator of Piloting Tasks
Mohammad Reza Mortazavi, Kamran Raissi, Seyed Hamed Hashemi,
Volume 4, Issue 4 (3-2017)
Abstract

Introduction: Pilot performance investigation during multi-tasking operations requires a procedure, in which the parameters related to the desired scenario of the simulator are obtained in a systematic manner. The multi-attribute task battery (MATB-II) is a standard simulator of generic piloting tasks developed by national aeronautics and space administration (NASA).

Methods: Employing information theory concepts, baud rate generated in all subsystems of the MATB-II were calculated and then, a unique numerical index presenting an estimation of overall workload was extracted. In the next step, three tests with different levels of workload were conducted to examine the validity of the offered criteria. These tests were performed by a group of subjects on the role of human pilots, while recording their own experiences about perceived workload via NASA-TLX.

Results: The results confirmed that there were significant differences between averages of scores assigned by subjects to the total workload, for three levels of difficulty defined based on information theory (P-value < 0.001). This variable shows considerable growth from low to medium and from medium to high categories of workload level.

Conclusions: The proposed quantitative index is effective enough for determination of workload levels in the MATB-II simulator.


The effects of ergonomic interventions in manual activities to reduce musculoskeletal disorders in manual activities by ManTRA
Sara Dehnavi, Abdollah Vahedi, Majid Motamedzade Torghabe, Abbas Moghimbeigi,
Volume 4, Issue 4 (3-2017)
Abstract

Abstract:

Introduction: Work-related musculoskeletal disorders (WMSDs) occur when the pressure that applied to musculoskeletal tissue is/be more than tissue tolerant capabilities. This study aimed to assess the risk factors cause musculoskeletal disorders associated with manual tasks using ManTRA and conducted ergonomics intervention program(educational- engineering) among workers in the printing industry.

MethodS: In this interventional case-control study, 40 workers who performed manual tasks, ( 20 case group and 20 control group) were chosen and were investigated. Nordic Body Map was used to determine the intensity and position of pain in the Different part of the body.  ManTRA method was performed to evaluate cumulative scores in four regions of the body (wrist / hand / arm - shoulder / neck - back - lower limb) for each workers before and after the intervention. Data analysis was done using SPSS.

Results: Data analysis showed that mean intensity of  pain in the control group before and after intervention in the various regions of the body such as  head /neck (p=0.012), right shoulder/arm (p=0.012), left shoulder/arm(p=0.043), back (p=0.003), right hand / wrist (p=0.028), left hand / wrist (p=0.027), right knee/ hip (p=0.005), left knee/ hip (p=0.005), right leg (p=0.012) & left leg(p=0.028) were significant.Cumulative score was also significant in the body regions such as arm/wrist /hand (p=0.001) and shoulder /neck (p=0.001) before and after the interventional program.

Conclusion: On the basis of the findings of this study, it could be noted that the ergonomic interventional program was effective to reduce the intensity of pain in the various regions of the body and risk factors causing cumulative damage in the workplace.

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Designing Bike Shift Lever with User-Centric Design Approach
Bahram Ipaki, Zahra Merrikhpour,
Volume 6, Issue 3 (10-2018)
Abstract
Background and Objectives: One of the important points in user-centric design is to pay attention to the physical and psychological conditions of the user and the errors caused by the product’s undesirable design. The bicycle shifting system is one of the most complex components that many interactions of users with it have an effect on them. This research recognizes the exact needs of cyclists and provides a solution to create effective user interaction.
Methods: In this research, using a combination method, a qualitative analysis was carried out using the AEIOU method, 50 cyclists of the Tabriz Islamic Art University were selected using non-random sampling method. Using a desirability testing of 3 subjects, a quantitative survey was done. After the preparation of the design requirements, by using SCAMPER technique, ideas were evaluated through DFV technique and the final idea was developed. 
Results: The results showed that users are faced with more psychological than physical problems during a gear shift. According to the desirability testing, the subject (2) with a score of 883, and the ratio of desirability of 1.212 compared to the subject (3) and 1.256 compared to the subject (1), was the most desirable product, which indicates the direct relation of the utility rate with the simplicity.
Conclusion: Since most users’ mistakes in understanding the logical displacement of the gears lead to poor bike switching conditions, the design of the product focuses on reducing user error and the number of additional operations and accelerating the user decision making process.
 

Investigating the Relationship Between the Risk of Psychosocial Factors and Grip Fatigue of Employees with Manual Tasks
Neda Mahdavi, Javad Faradmal, Iman Dianat, Hassan Khotanlou, Rashid Haidari Moghadam,
Volume 8, Issue 3 (10-2020)
Abstract
Backgrond and Aim: Fatigue is a common and highly prevalent problem among workers. Muscle fatigue is the result of general fatigue that is caused by different risk factors. This research was conducted to assess grip fatigue between workers with manual tasks and its relationship to psychosocial risk factors.
Methods: In this study, Jamar hydraulic dynamometer was used to investigate the decrease in the production of grip force or grip fatigue. The grip force of 157 subjects in three job levels that met inclusion criteria recorded, three times in an 8 hours shift. The psychosocial risk factors were also assessed using the Copenhagen psychosocial questionnaire and their relationship with grip force and grip fatigue was analyzed.
Results: sixty-one percent, 62%, and 69% of employees in light, medium, and heavy tasks, respectively, experienced grip fatigue in the second phase of the study. It seems that as the power/speed increased and the tasks became more difficult, employees experienced more grip fatigue in the right hand. The declining trend of grip force and the increase in grip fatigue was more evident in heavy task jobs. No moderate or strong correlation was observed between the psychosocial risk factors and grip fatigue.
Conclusion: Because the nature of worker tasks in heavy manual tasks required more force exertion, they experienced more grip fatigue in their right hand than other workers. It is not possible to draw definitive conclusions about the impact of psychosocial risk factors on grip fatigue. Investigating the impact of cognitive loads and anthropometric dimensions on grip fatigue can be an interesting topic for future studies.

Identification and Assessment of Human Error during the Process of Operating Various Types of Fire Apparatus
Tahmineh Moradi Tamadon, Fakhradin Ghasemi, Iraj Mohammadfam, Omid Kalatpour,
Volume 8, Issue 4 (1-2021)
Abstract
Background and Objectives: Firefighting is a difficult and dangerous job. This job requires decision-making and speed in action in critical situations. Such conditions increase the probability of human error in the firefighting activities. Setting up fire operators as the first step of emergency response is associated with high criticality. The purpose of this study is identification and assessment of the risk of human error while setting up and operating fire operators.
Methods: This descriptive cross-sectional study was performed in 2019. Tasks related to the operation of industrial firefighting operators were studied and analyzed by Hierarchical Task Analysis. Then, human errors in the operation of fire operators were identified and analyzed using the systematic human error reduction and prediction approach (SHERPA). Finally, appropriate prevention solutions were proposed to reduce the risk of errors.
Results: A total of 480 errors were detected for 130 tasks as 49.58% of them were action errors, 39.17% check type, 10.42% communication and 0.83% were selective errors and no retried error was observed. According to the results of risk assessment, 8.33% of the errors were unacceptable, 24.17% were undesirable, and 48.33% were acceptable risks but needed to be revised and 19.17% were acceptable without the need for revision.
Conclusion: The process of operating fire operators can be associated with human errors and prevent successful firefighting operations. Therefore, these errors should be identified and controlled using appropriate methods.

Measuring User's Emotional Experience in Two Tools Using an Integrated Method Based on Task Analysis
Narges Adabi, Hassan Sabourimoghaddam, Abbas Bakhsheepour Roodsari,
Volume 10, Issue 3 (12-2022)
Abstract
Objectives: Human factors are critical in the design and development of various products, but wideness and unclarity of different aspects of these factors make it difficult to extract demands of users. Studying emotional aspects of users' behavior in interaction with products, as well as interviewing them, is considered as an efficient tool in extracting design demands. This study aims to integrate the application of task analysis and the measuring of emotional aspects to determine the users’ emotional states in the different stages; and therefore extract the user satisfaction criteria.
Methods: This research has a descriptive/ exploratory approach. In this practical study, the use of two everyday tools for chopping onions is analyzed. 20 users of these tools were non-randomly selected to participate in the test and interview. Users performed the task with each tool, and the process was recorded by a camera. After performing the task, subjects completed self-assessment questionnaire and then, an interview was conducted about their experience of the tools usage. Parametric t test was used to evaluate results of the questionnaire and compare averages.
Results: Findings of the emotional questionnaire showed that the emotional states of people in different stages of task are significantly different from each other. The determined emotional states, showed the weaknesses and the advantages of the tools studied. By analyzing videos, interviews and surveys, users' demands were extracted. The extracted features were categorized based on the work steps.
Conclusion: Using this method can reveal precise details of users’ needs concerning product category, which can be used as a suitable tool for designers and researchers in the field of user experience.

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