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Latest version of
Mento software

The latest version of Mento-factor Compact software is MF-C 1.10 of August 2013.

Measuring Mental Load/Strain with RWF
July 2013

Sociological and psycho-social studies have shown that not only decrease of physical stress was able to reduce or eliminate work distress. Mental strain also has a essential influence on job satisfaction. All this led to many research, investigations and enquiries. The following conclusions were drawn: regarding the content of the work one may distinguish between stress or strain of the muscles (the energetic component) and the stress or strain of the brain, viz. steering and/or controlling working behaviour (the mental component).
Therefore it is stated that mental load is the strain arising from the steering, controlling and completing of the external and internal working behaviour of man. (from: “Mentale werkbelasting en arbeidssatisfactie” of Dr. J.W.H. Kalsbeek).

Starting point
In RWF every task or operation is analyzed in small motions or movements (the standard elements), which, depending on the weight ánd the body part that performs that movement ánd the difficulty of that movement, is expressed in a number of work-factors, WF’s. With this goes also a mental load which will be valued and expressed in a number of mento-factors, MF’s.

Remarks on measuring mental load during manual labour are:
- Each motion as part of a task or operation, is a little piece that fits in the program of that task or operation.
- In order to execute a task, it is necessary that the worker knows that program (the working sequence) very well.
- When the task must be executed, all body members concerned receive from the brain the assignment to execute a
  particular motion.
- For small motions in many cases it will be enough for the brain (the memory) just to give the order and that the body part
  executes the task without any attention of the worker (automatism).
- These small motions give rise to very little mental load, almost to be ignored.
- As these motions get heavier, with more weight, more difficult or more frequent to execute, besides the initial order itself
  more attention must be given to the task during execution also ordered and controlled by the brain.

Following the afore mentioned starting point and remarks, it is possible to classify the RWF tables into load and strain factors regarding mental load, the so-called mento-factors, MF’s. To make these tables more suitable for practical use, for each standard element, the tables are split into groups (colours or striping) in such a way that the mental load per element is more or less equal.
In RWF 7 categories of mental load are distinguished, viz. 0 MF, 1 MF, 2 MF, 4 MF, 8 MF, 16 MF and the special category of 128 MF/sec for 100% mental work.

A new module on Mental Load has been build into the existing WFS-RWF program to be able to assess and evaluate existing RWF analyses in order to get insight in the “importance” of mental load during manual labour.

From the analyses on Binairy Choice Tasks (Binaire KeuzeTaken) executed so far, it has been shown that the classifcation of mental load into the predefined categories None, Too Low, Low-Normal, Normal-High, High, Heavy, Too Heavy, are very much in accordance with the categories defined by Kalsbeek c.s.

The new ML-module and the extension of the MP-module ar now being tested on robustness, little flaws and faults. We call on all RWF analists to take some interest and join us to experiment with this new module to gain some experience in a practical testing environment. For analists familiar with Mento-Factor Compact and alreay using the MF-C module or willing to use it, it is recommendable to contact the secretariat in order to use and test the new MF-C module.

July 2013

Chapter 7 of the Mento-Factor Compact manual has been differently arranged viz. into 7.1 Contrast, 7.2 MP Inspection, 7.3 MP Read inclusive Memorize and Remember, 7.4 MP Count, 7.5 MP React, 7.6 Summary. So, the chapter is extended with a paragraph on React/Decide (Rn). With this paragraph the MF-C manual comprises of 4 Mento Intervals: Inspect Interval, Read Interval, Compute Interval and React Interval.
The (new) Rn-tabel distinguishes between reaction on a) expected signals ofwhich is known which signal it is and when it will occur, b) expected signals ofwhich it is known which signal it is or when it will occur and c) unexpected signals ofwhich it is unknown what signal it is and when it will occur.

Times in the table are applicable for normal light-, sound- or pressure signals. With a “correction factor” the table may also be used for decisions on approval or reject of parts and products on quality a.t.l., as with tasks on checking on scratches, dents, staints etc.

This extension of MF-C has also been integrated into the Mento modul of RWF, VWF and BWF, version 1.10.
An error was detected in the calculation of the number of Inspection Units for fix distances not equal the fix distance normal, FDN and hence the wrong number of IE’s were shown, mostly too less. This flaw was also corrected.

MF-C version of
January 2012

On request of the WFR, it is made easier to include Focus, Inspect and React as basic element into the analyses. Also some minor imperfections are resolved.
This new version of MF-C is released by the WFGD through version WFS 6.06 of January 2012 as version MF 1.01.

December 2011

the Mento-Factro Compact Manual is extended and adapted at the chapters about Visual inspection and Seeing Colour. The chapters about Notions, Eye motions and Mental Processes and Span are adapted and improved.

New version of
MF-C, Sept. 2007

The new version of Mento-Factor Compact developed by the WFGD is available since the version embedded in the beta release of WFS 5.92 in September 2007, MF-C 1.00.
On request of the WFR it has been made easier to analyse Focus, Inspect and React. Also some minor imperfections are dealt with and resoloved.


The Mento-Factor Compact manual has been extenden and modified at the chapters on See: Visual Inspection and Colour. The chapters on Notions, Eye movements and Mental Processes and Span are somewhat adapted and improved.
January, 2007


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