physiology and work measurement tutorial 4...

tutorial 4

Prodi Teknik IndustriFakultas Teknologi IndustriUniversitas Islam IndonesiaTahun Ajaran2016/2017

mental workload

PHYSIOLOGY AND WORK MEASUREMENT

www.labdske-uii.com

Mental Workload 2016

Laboratorium Desain Sistem Kerja & Ergonomi | 1

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.



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



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.



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.



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.



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).



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



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



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



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.



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



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



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



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



D. PRACTICUM

Mental workload groove for the practicum described in the following flowchart :



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).

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