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tutorial 4
Prodi Teknik IndustriFakultas Teknologi IndustriUniversitas Islam IndonesiaTahun Ajaran2016/2017
mental workload
PHYSIOLOGY AND WORK MEASUREMENT
www.labdske-uii.com
Mental Workload 2016
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MENTAL WORKLOAD
A. DESCRIPTION
The workload is a consequence of activities provided to workers. The activity of
the worker essentially indistinguishable between physical activity and mental activity. In
practice the workload that you found is a combination of the physical workload and the
mental workload. According Henry R.Jex (1988), mental work load is the difference
between workload demands of an assignment with a maximum load capacity of a
person's mental condition motivated.
Measurement of mental workload can be done in two ways, namely objective
measurements can be performed by several members of the body include eye blink,
flicker test and measurement of salivary acids. As for subjective measurement can be
done using the NASA-TLX, Subjective Workload Assessment Technique (SWAT),
Harper Qoorper Rating (HQR), and Task Difficulty Scale. Measurement of a subjective
mental workload is a measurement technique that is most widely used because it has a
high degree of validity and direct comparison with other measurements.
Special Purpose:
1. Able to quantify subjective mental workload of the operator with NASA-TLX
indicator.
2. Able make intrepetation and analyze the performance score calculation mental
workload on a particular job.
3. Able to provide recommendations based on the analysis results.
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B. INPUT AND OUTPUT
Input:
a) NASA-TLX questionnaire
b) Total Weight Indicator Tally NASA-TLX
c) Ratings Indicators NASA-TLX
d) Type of Work
Output:
a) Result of NASA-TLX questionnaire
b) Score NASA-TLX
c) Categories of mental workload on the job
d) Recomendations of workload
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C. THEORY
1. Workload Definitions
The workload is a effort that must be issued by a person to complete the "demand"
of the job. While capacity is the ability / capacity of human beings. This capacity can be
measured from a person's physical and mental condition. The workload in question is the
size (portion) of the limited capacity of the operator is required to do work tertentu.
According Herrianto (2010) workload is the number of activities that must be completed
by a person or group of people during a specific time period under normal circumstances.
To achieve normal work load in terms of the volume of work in accordance with
work ability is quite difficult, so it is always an imbalance despite the small
penyimpangannnya. The workload is divided into three levels, namely:
1) Workload above normal means that the time used to complete the job is greater
than the available working hours or volume of work exceeds the ability of the
work;
2) Cost of normal working time means used to accomplish the same job of
available working hours or volume of work together with the ability of workers;
3) The workload under normal meaning that the time used to complete the job less
than the available working hours or volume of work is lower than the ability of
the work.
1.1 Factors Affecting Workload
Workload is influenced by two factors, namely external and internal factors.
According Tarwaka (2004 ) , the factors that affect the workload among others :
a. External factors , namely the burden that comes from outside the body of workers ,
such as ;
1. Physical task, such as work stations, spatial, workplaces, equipment and means of
work, working conditions, work attitude, and the tasks that are psychological, such
as job complexity, difficulty level, job responsibilities.
2. Labor organizations, such as the length of time work, time off, shift work, night
work, wage system, the model organizational structure, delegation of tasks and
authority.
3. The working environment is the physical work environment, chemical
environment, work environment and biological psychological work environment.
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b. Internal factors
Internal factors are factors originating from within the body itself a result of a
reaction to an external workload. Internal factors include somatic factors (gender, age,
body size, nutritional status, and health conditions) and psychological factors
(motivation, perception, belief, desire and satisfaction).
2. Mental WorkLoad
A. Definition of Mental Workload
According to Henry R. Jex, 1998, in his book
"Human Mental Workload", mental workload is:
"The workload which represents the difference
between the demands of the workload of a task with a
maximum load capacity of a person in a state mental
motivated".
Excessive mental workload will result in a
stressful job. According to Lazarus (in Fraser, 1992)
says that the job is stressful events surrounding a workplace hazard or threat such as fear,
anxiety, guilt, anger sadness, despair, boredom, and the incidence of workplace stress
due to workload beyond acceptable limits the ability of workers that took place in a
relatively long time in certain circumstances.
B. Impact of Mental Overload Workload
There are some indications effect of excessive mental overload , as described by
Hancock and Mesahkati (1988 ) :
a. Physical indication
Headache, abdominal pain, easily startled, disruption of sleep patterns lethargy, stiff
neck back to backs, decreased appetite and others.
Stoner (1986) says that a different job for each worker will lead to different
levels of work stress as well. Work stress affect directly or indirectly to aspects
of the work, especially the achievement motive that will be associated with the
work process.
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b. Mental indication
Forgetfulness, difficulty concentrating, anxiety, irritability, irritability, anxiety, and
despair.
c. Social or behavioral indication
Many smoke, drink alcohol, withdrawal and avoidance.
C. Mental Workload Control Excessive
How to prevent and control occupational stress by Sauter (1990 ) in Prihatini (2007 )
is as follows
1. Mental workload should be adjusted to the ability and work capacity of workers
concerned with avoiding any overload or workload was too light.
2. Working hours should be adjusted well to the demands of the task and
responsibilities outside the job.
3. Every worker should be given the opportunity to develop a career, get promotion
and development expertise.
4. Forming healthy social environment that is between workers with each other.
5. Tasks should be designed to be able to provide stimulation and opportunities for
workers to use their skills.
D. Workload Measurement
1) Objective Measurement Methods
Based Widyanti et al. (2010), mental workload can be measured by physiological
approach (as quantified by objective criteria, it is called an objective method). On a
worker mental fatigue caused by the functional reactions of the body and the center of
consciousness. Approaches that could be done include:
1. Measurement interval blink of an eye (eye blink rate)
The duration of eye blinks can show the level of workload experienced by a person.
People who experience severe labor and tired eyes will blink duration is usually
longer, while for people working light (not burdened mental or psychological), the
duration of the relatively fast twinkle in his eye.
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2. Flicker test
This tool can show differences in the performance of the human eye, allowing for
differences flicker value of each individual. This flicker rate differences are
generally strongly influenced by heavy / light work, especially work-related eye.
3. Measurement of saliva acid levels
Installing special tools to determine the workload that workers involving the mouth,
mainly produced by three pairs of major salivary glands are located outside the oral
cavity.
3) Subjective Measurement Method
While the workload measurement method according Widyanti suyektif et al. (2010)
is a measure of mental workload based on subjective perceptions of respondents /
employees. Here are a few types of subjective measurement methods :
1. Subjective Workload Assessment Technique (SWAT)
2. National Aeronautics and Space Administration Task Load Index (NASA - TLX)
3. Modified Cooper Harper Scaling
4. Multidescriptor Scale
5. Rating Scale Mental Effort ( RSME )
Stages of Mental Workload Measurement In Subjective:
1. Determining factors of mental workload observed work.
2. Determine the range and value of the interval.
3. Choose the section factor significant workload for specific tasks.
4. Determine the subjective errors are taken into account in estimating the impact and
studying the workload.
Measurement objectives by Subjective Mental Workload
1. Determine the best scale based on experimental calculations in the experiment.
2. Determine the difference in scale for different types of jobs.
3. Identify mental workload factors that are significantly associated subjective and
based on empirical research using a rating workload certain population sample.
From some of these methods the method most widely used and proven to provide
good results is the NASA-TLX and SWAT (Hancock and Meshkati, 1988).
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3. NASA - TLX
A. Definition of NASA - TLX
NASA - TLX method (National Aeronautics and Space Administration Task Load
Index) is a method used to analyze mental workload faced by workers who have to
perform various activities in his work. Methods NASA - TLX was developed by Sandra
G. Hart of NASA-Ames Research Center and Lowell E. Staveland from San Jose
State University in 1981, this method is a
questionnaire developed by the emergence of
subjective measurement scale consisting of nine
factors ( task difficulty, time pressure, type of
activity, physical effort, mental effort,
performance, frustration, stress and fatigue). Of the
nine factors are further simplified into 6 Needs
Mental demand (MD), Physical demand (PD),
Temporal demand (TD), Performance (P), frustation level (FR) .
NASA - TLX ( NASA Task Load Index ) is a method of mental workload subjective
measurement. NASA - TLX measurement method is divided into two phases, namely the
comparison of each scale (Paired Comparison) and giving value to the work (Event
Scoring) .
B. NASA-TLX Indicator
In measuring the NASA-TLX are 6 indicators that must be considered (Hancock and
Meshkati, 1988), namely:
Table 4.1 NASA-TLX Indicators
SCALE RATING EXPLANATION
MENTAL
DEMAND (MD)
Low
High
How much is the mental and perceptual
activity required to see, given the hard work
and find ,if it is simple or complex. Loose or
tight
PHYSICAL
DEMAND (PD)
Low
High
Amount of physical activity required (eg,
pushing, pulling and rotation control).
The bottom line here is that the
measured workload of the type
of work, not the work load that
is owned by each worker
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SCALE RATING EXPLANATION
TEMPORAL
DEMAND (TD)
Low
High
The amount of stress associated with perceived
time during the last job elements. Whether
casual or work slowly or quickly and
exhausting
PERFORMANCE
(OP)
Not
Accurate,
Perfect
How big is a person's success in the job and
how satisfied with their work
FRUSTATION
LEVEL (FR)
Low
High
How insecure, discouraged, irritable, distracted
with their work
EFFORT (EF) Low
High
How hard did you have to work to accomplish
your level of performance
C. NASA-TLX Measurement Step
Step measurement using the NASA TLX is as follows (Hancock and Meshkati,1988)
1. Weighting
In this section respondents were asked to choose one of two indicators of perceived
dominant cause of mental workload on the job. NASA-TLX questionnaire is given in the
form of pairwise comparisons. The calculated number of questionnaires tally of each
indicator that is felt most influential. Tally a number of weights for each indicator of
mental load. The following comparison table NASA TLX indicators:
Table 4.2 Comparative indicators
MD PD TD OP EF FR
MD
PD
TD
OP
EF
FR
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2. Giving Rating
In this section, respondents are asked to rate the six indicators of mental load.
Subjective rating given is dependent on the mental burden felt by the respondents. To get
a score of NASA-TLX mental load, weight and rating for each indicator were then
summed and divided multiplied by 15 (the number of pair wise comparisons).
The following rating scale of NASA-TLX:
Figure 4.1 NASA TLX Rating
3. Calculating the value of the product
Rating is obtained by multiplying the weight factor for each descriptor. Thus
produced 6 value products for 6 indicators (MD, PD, TD, CE, FR, EF):
Product = Product rating x Weighting Factor
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4. Calculating Weighted Workload (WWL)
Value is obtained by summing the six products
5. Calculate the average WWL
WWL is obtained by dividing the total number of weights
6. Interpretation of Score
Based on the explanation and Staveland Hart (1981) in the theory of the NASA-
TLX, workload score obtained is divided into three partsTabel 3. Skor NASA-TLX.
Table 4.3 Score NASA-TLX
Workload
Group
Score
Low 0 - 9
Moderate 10 - 29
Kinda high 30 - 49
High 50 - 79
Very high 80 - 100
Output generated from measurements with NASA-TLX is a level of mental
workload experienced by workers.
The measurement results can be considered management to make
recommendations as to reduce the workload for jobs that have a score above
80, then allocate the work that has workload under 50 or other measures.
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Case examples of measurement methods NASA-TLX
In this case the measurement of mental workload on work in the field of transport,
especially on the job as public transport drivers, taxi drivers and driver travel on one of the
terminals in Yogyakarta. The following process steps:
1. Weighting
Questionnaires comparative indicators in Table 4.4 were distributed to 3 respondents
working at the same place. Then do the recapitulation to tally the number of
questionnaires distributed so as to get the following results:
Table 4.4 Indicators
Table 4.5 Weighting Quetionnaire Data
Object Indicator Total
MD PD TD OP EF FR
Public Transport
Driver
1 4 4 3 3 0 15
Taxi Driver 2 2 4 1 3 3 15
Travel Driver 2 3 2 4 0 4 15
EFMDPD
PDTD OP EF
PD
TDPD
TD TD
OP OPEF
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2. Giving Rating
Giving rating obtained from observation sheets completed by the third operator after
completing BKM Test, operators were asked to provide ratings on indicators of
mental workload and the rating given the subjective nature in accordance with the
mental burden felt by the operator for each job. Results can be seen in Table 4.6. as
follows:
Table 4.6 Result of Rating
ObjectIndicator
MD PD TD OP EF FR
Public Transport
Driver
70 90 40 40 80 0
Taxi Driver 60 70 80 50 70 70
Travel Driver 70 90 60 40 80 60
3. Product Value Calculation
Defined by multyplying rating with weight factor to each descriptor. So that as result
6 products value for 6 indicators (MD, PD, TD, CE, FR, EF):
Table 4.7 Total Value Products
ObjectIndicator
MD PD TD OP EF FR
Public Transport
Driver
70 360 160 120 240 0
Taxi Driver 120 140 320 50 210 210
Travel Driver 140 270 120 160 0 240
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4. Weighted Workload (WWL) Measuring
Defined by summing 6 product value, the result as follows:
Table 4.8 WWL Total
ObjectIndicator Total
MD PD TD OP EF FR
Public Transport
Driver
70 360 160 120 240 0 950
Taxi Driver 120 140 320 50 210 210 1050
Travel Driver 140 270 120 160 0 240 930
5. Measuring WWL Average
Defined by dividing WWL with total weighting value, the result as follow :
Table 4.9 WWL average
ObjectIndicator Total
MD PD TD OP EF FR
Public Transport
Driver
4,67 24 10,67 8 16 0 63,3
Taxi Driver 8 9,33 21,33 3,33 14 14 70
Travel Driver 9,33 18 8 10,67 0 16 62
6. Score Intrepetation
From total average WWL obtained, based on Table 4.10 Obtained at each job
category driver as follows:
Table 4.10 Category Reviewing Workload
ObjectValue
MentalWorkloadCategori
Public Transport
Driver63,33 High
Taxi Driver 70 High
Travel Driver 62 High
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7. Analysis of Results
7.1 Mental Workload public transport drivers
Based on the calculation of the workload that has been done using the NASA-TLX,
mental work load on the operator one who works as a driver of public transport 63,33.
So based on these values, the work load experienced by the operator 1 is at 50-79,
which means high workload. The dominant factor resulting from a high workload on
the carrier 1 is the factor of physical strength, in which the results of the calculations
can be seen that one of the activities that make the operator 1 burdened is in terms of
physical needs (PD) where the operator 1 aged > 40 years are required to worked as a
driver of public transport around the city looking for passengers from morning until
late afternoon so it requires a lot of energy in doing his job.
EXERCISE
In this case the measurement of mental workload on nurses clinic performed surgical, eye,
physiotherapy, neurology internist and as many as 8 respondents (Hidayat et al, 2013). It is
known weighting of recapitulation on the number of questionnaires distributed tally get
results in Table 4.11 and granting rating is also unknown at Table 4.12 So how much
balanced interpretation of each job ?
Tabel 4.11 Weighting Quetionnaire Data
Tabel. 4.12 Giving rating
FR
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D. PRACTICUM
Mental workload groove for the practicum described in the following flowchart :
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E. REFERENCE
Fraser. 1992. Stres dan Kepuasan Kerja. Jakarta: Pustaka Binawan Pressindo.
Hancock, P. A. & Meshkati, N. 1988. Human Mental Workload. Elsevier.
Hart, S. G. 2006. NASA-Task Load Index (NASA-TLX), 20 years later. In Human
Factors and Ergonomics Society 50th Annual Meeting (pp. 904-908). Santa Monica,
CA: Human Factors and Ergonomics Society.
Henry, R. J. 1988. Human Mental Workload. New York, USA: Elsevier Science
Publisher B.V.
Herrianto, R. 2010. Kesehatan Kerja. Jakarta: Buku kedokteran EGC.
Hidayat, T.F., Pujangkoro,S. & Anizar. 2013. Pengukuran Beban Kerja Perawat
Menggunakan Metode NASA-TLX di Rumah Sakit XYZ. FT USU: e-Jurnal Teknik
Industri. 1(2), pp.42-47.
James, A.F.Stoner. 1986. Manajemen II. Jakarta: Erlangga.
Kementerian Pendayagunaan Aparatur Negara Republik Indonesia. 2004. Pedoman
Perhitungan Kebutuhan Pegawai Berdasarkan Beban Kerja dalam Rangka
Penyusunan Formasi Pegawai Negeri Sipil (Kep. Men. PAN Nomor :
KEP/75/M.PAN/7/2004). Jakarta.
Manuaba. 2000. Ergonomi, Kesehatan, dan Keselamatan Kerja. Surabaya: Guna Widya
Purnomo, H. 2014. Metode Pengukuran Kerja. Yogyakarta: Sigma
Prihatini. 2007. Analisis Hubungan Beban Kerja dengan Stres Kerja Perawat di Tiap
Ruang Rawat Inap RSUD Sidikalang, Medan.
Tarwaka. 2004. Ergonomi untuk Keselamatan Kesehatan Kerja dan Produktivitas.
Universitas Islam Surakarta: Penerbit UNIBA Press.
Widyanti, A., Johnson, A. & Waard, D.d. 2010. Pengukuran Beban Kerja Mental Dalam
Searching Task Dengan Metode Rating Scale Mental Effort (RSME). JTI Universitas
Diponegoro, 1(V).
www.labdske-uii.com
Allah will exalt in degree those of you who believe,
and those who have been granted knowledge
QS 58:11