SIST EN ISO 10075-2:2025

SLOVENSKI STANDARD
01-januar-2025
Nadomešča:
SIST EN ISO 10075-2:2002
Ergonomska načela v zvezi s psihičnimi obremenitvami - 2. del: Načela za
načrtovanje (ISO 10075-2:2024)
Ergonomic principles related to mental workload - Part 2: Design principles (ISO 10075-
2:2024)
Ergonomische Grundlagen bezüglich psychischer Arbeitsbelastung - Teil 2:
Gestaltungsgrundsätze (ISO 10075-2:2024)
Principes ergonomiques relatifs à la charge de travail mentale - Partie 2 : Principes de
conception (ISO 10075-2:2024)
Ta slovenski standard je istoveten z: EN ISO 10075-2:2024
ICS:
13.180 Ergonomija Ergonomics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 10075-2
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2024
EUROPÄISCHE NORM
ICS 13.180 Supersedes EN ISO 10075-2:2000
English Version
Ergonomic principles related to mental workload - Part 2:
Design principles (ISO 10075-2:2024)
Principes ergonomiques relatifs à la charge de travail Ergonomische Grundlagen bezüglich psychischer
mentale - Partie 2 : Principes de conception (ISO Arbeitsbelastung - Teil 2: Gestaltungsgrundsätze (ISO
10075-2:2024) 10075-2:2024)
This European Standard was approved by CEN on 14 July 2024.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10075-2:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 10075-2:2024) has been prepared by Technical Committee ISO/TC 159
"Ergonomics" in collaboration with Technical Committee CEN/TC 122 “Ergonomics” the secretariat of
which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2025, and conflicting national standards shall
be withdrawn at the latest by January 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 10075-2:2000.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 10075-2:2024 has been approved by CEN as EN ISO 10075-2:2024 without any
modification.
International
Standard
ISO 10075-2
Second edition
Ergonomic principles related to
2024-07
mental workload —
Part 2:
Design principles
Principes ergonomiques relatifs à la charge de travail mental —
Partie 2: Principes de conception
Reference number
ISO 10075-2:2024(en) © ISO 2024

ISO 10075-2:2024(en)
© ISO 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
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or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 10075-2:2024(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Design principles . 2
4.1 General principles .2
4.2 Design principles in relation to work organisation .3
4.2.1 Perform system design reviews and include prospective risk assessment .3
4.2.2 Individuals’ and team work-related objectives .3
4.2.3 Extended reachability . .4
4.2.4 Flexibility in time allocation .4
4.2.5 Definition of work-related services .5
4.2.6 Duration of working hours .5
4.2.7 Time off between successive work days or shifts .5
4.2.8 Time of day .6
4.2.9 Shift work .7
4.2.10 Breaks and rest pauses .7
4.3 Design principles in relation to working tasks .7
4.3.1 Operating strategies .7
4.3.2 Continuous time constraints .8
4.3.3 Flexibility of decision-making .8
4.3.4 Ambiguity of task goals .9
4.3.5 Complexity of task requirements .9
4.3.6 Time sharing .10
4.3.7 Dimensionality of motor performance .10
4.3.8 Mental models .11
4.3.9 Parallel versus serial processing .11
4.3.10 Decision support . .11
4.3.11 Sustained attention . 12
4.4 Design principles in relation to job . 12
4.4.1 Social interaction . 12
4.4.2 Dependencies on others' task performance . 13
4.4.3 Identical task requirements . 13
4.4.4 Confidential communication .14
4.4.5 Changes in task-related activities with different demands or types of mental
workload .14
4.5 Design principles in relation to work equipment and interfaces .14
4.5.1 Design the socio-technical system transparent for the user .14
4.5.2 Re-evaluate after adopting an assistance system to an existing system . 15
4.5.3 Time lag . 15
4.5.4 Adequacy of information . . 15
4.5.5 Ambiguity of information .16
4.5.6 Signal discriminability .16
4.5.7 Redundancy .16
4.5.8 Compatibility .17
4.5.9 Accuracy of information processing .18
4.5.10 Controllability .18
4.5.11 Control dynamics .18
4.5.12 Tracking requirements .19
4.5.13 Error tolerance .19
4.5.14 Adjust system design .19
4.5.15 Anticipate shifts in operating states and potential consequences . 20
4.5.16 Coupling in human-machine arrangements . 20

iii
ISO 10075-2:2024(en)
4.5.17 Adaptable and adaptive human–automation interaction .21
5 Information and training .21
Annex A (informative) Design principles and their relation to the impairing consequences of
mental strain.22

iv
ISO 10075-2:2024(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 1, General
ergonomics principles, in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 122, Ergonomics, in accordance with the Agreement on technical cooperation between
ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 10075-2:1996), which has been technically
revised.
The main change is as follows:
— The structure is now based on working conditions and no longer on strain consequences. All design
principles are formulated positively and are divided into three parts, namely justification, guidelines
and examples.
A list of all parts in the ISO 10075 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
ISO 10075-2:2024(en)
Introduction
This document represents an extension of ISO 6385, providing design principles for work systems with
special reference to mental workload as defined in ISO 10075-1.
Mental workload is the effect of a complex interaction of individual, technical, organisational and social
factors. Thus, personnel, technical, organisational and social factors and the effects of their interactions are
relevant for the design of work systems.

vi
International Standard ISO 10075-2:2024(en)
Ergonomic principles related to mental workload —
Part 2:
Design principles
1 Scope
This document gives guidance on design principles and on design of work systems, including task and
equipment design (comprising robotics and intelligent autonomous systems) and design of the workplace,
as well as working conditions with the inclusion of social and organisational factors, emphasising mental
workload and its effects as specified in ISO 10075-1.
It applies to the design of work and use of human capacities, with the intention of providing optimal working
conditions with respect to health and safety, well-being, performance and effectiveness, preventing overload
as well as underload, in order to avoid impairing effects and fostering the facilitating effects described in
ISO 10075-1.
This document includes the design of technical, organisational and social factors only and does not apply to
problems of selection or training.
This document does not address problems of measurement of mental workload or its effects.
This document refers to all kinds of human work activities (see ISO 10075-1), not only to those which can
be described as cognitive or mental tasks in a restricted sense but also to those with a primarily physical
workload.
This document is applicable to all those engaged in the design and use of work systems, for example system
and equipment designers, employers and workers and their representatives, where they exist.
This document is applicable to the design of new work systems as well as to the redesign of existing ones
undergoing substantial revision.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 6385, Ergonomics principles in the design of work systems
ISO 10075-1, Ergonomic principles related to mental workload — Part 1: General issues and concepts, terms and
definitions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 6385 and ISO 10075-1 apply.
ISO and IEC maintain terminology databases for use in standardisation at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/

ISO 10075-2:2024(en)
4 Design principles
4.1 General principles
In order to avoid impairing effects and to foster facilitating effects of work system design on users, the
work system must fit the user. The guidelines given in this document are recommendations concerning
human-factors or ergonomics-related work design. Designing or redesigning work systems entails taking
into account: people, technology, organisational and social conditions and their interactions right from the
beginning, for example when planning work systems. This means that ergonomists should be integrated
into the design process as early as possible. Where appropriate, stakeholders should be involved in the
design process.
If there are already users, as in system redesign, their experiences and competencies should be integrated
into the design or redesign process in order to achieve and verify an optimal level of design quality. This
can be done by using methods of participation, by which user expectations and needs, with respect to
design quality, can be incorporated into the design process. This enables user-oriented results and better
acceptance on the side of the user, which contributes to the efficiency of the work system as a whole.
Furthermore, feedback mechanisms are useful to enable workers to help the designer to continuously
improve the design, taking into account new situations or problems.
If the design is made for an entirely new system, the designer should take due account of the abilities, skills,
experiences, expectations and needs of the prospective user population. Training should be regarded as
supporting work system design, not as a replacement for system design omissions leading to sub-optimal design.
The user population must be considered from the beginning of the design process when system functions
are specified. Defining system functions and subfunctions as well as function allocation between workers
and technical systems and between different workers warrants consideration of the characteristics of the
people involved.
In designing work systems, it should be kept in mind that work consists of a combination of tasks, which
are executed with particular technical equipment in a particular work environment, in a particular
organisational and social structure. Therefore, each of these components offers opportunities to influence
the design of the work system with regard to mental workload.
Design principles can thus be related to different levels of the design process and the design solution in
order to influence:
a) the intensity of the workload:
— at either the task or job level, or both;
— at the level of technical equipment;
— at the environmental level;
— at the organisational and social level;
b) the duration of the exposure to the workload:
— at the level of the temporal organisation of work.
Table A.1 in Annex A shows a matrix of the guidelines and their relation to the impairing consequences of
mental strain.
Personnel factors, such as abilities, performance capacities and motivation (on an inter-individual as well
as on an intra-individual differences basis) influence the resulting workload. Thus, selection and training
should be taken into account in the design of work systems.
Work system design starts with a function analysis of the system, followed by function allocation among
worker and technical system and task analysis, and results in task design and allocation to the worker. It is
proven that human factor experts are integrated into this process from the beginning in order to be able to

ISO 10075-2:2024(en)
perform these steps with a view to the resulting design requirements, in particular with respect to mental
workload. Such a procedure will reveal the appropriate requirements to be taken into account at each level
of system design.
In designing work systems, it should be noted that environmental requirements, system demands, challenges
and people themselves change over time. People, for example, can develop skills, abilities and expectations.
This means that systems design should take into account such changes, enabling the system to adapt to
these evolving needs. This can be done, for example, by dynamic task allocation, allowing the worker to
allocate tasks to the technical system or to the worker, depending on the actual state of the worker.
Mental workload has different qualitative aspects leading to different qualitative effects (see ISO 10075-1).
It is thus not sufficient to consider workload ranging on a unitary dimension (quantitatively) from underload
to optimal load to overload. Some of the impairing effects of mental workload share common causes,
although the effects are different. Monotony and mental satiation occur in repetitive monotonous activities.
However, monotony is characterized by reduced activation and mental satiation by increased activation.
The presentation of the following guidelines has thus been organized according to the components in work
system design in ISO 6385 and with reference to impairing and fostering effects as described in ISO 10075-1.
This should help the designer to take appropriate measures to avoid impairing effects and to foster
facilitating effects of mental workload. Some of the guidelines are related to several consequences of mental
strain. Accordingly, there are different possibilities to avoid the impairing consequences of mental strain.
4.2 Design principles in relation to work organisation
4.2.1 Perform system design reviews and include prospective risk assessment
4.2.1.1 Justification
The evaluation of work processes at various stages of development allows for adjustments. The focus should
always be human-centred, since latent or occasional impairments due to working conditions can result in
reasonably foreseeable misuse, mental fatigue and stress responses during worker task performance.
4.2.1.2 Guidelines
The designer should:
— perform system design reviews;
— assess dynamics and the variability of health and safety risks during system design;
— include, in design reviews, the system life cycle, potential system states, system performance, contexts
of use, risks by system wear and tear, and reasonably foreseeable misuses.
4.2.1.3 Example
A building originally designed as a production site is planned to be used as an office or coworking space.
Offices and production sites have different illumination requirements. Illumination for office use is
suboptimal with regard to natural illumination and artificial illumination design.
4.2.2 Individuals’ and team work-related objectives
4.2.2.1 Justification
Objectives should be attainable within regular working hours, otherwise the worker can experience mental
fatigue, stress response or burnout.

ISO 10075-2:2024(en)
4.2.2.2 Guidelines
The designer should:
— define individuals' and team work-related objectives consistently and attainably;
— enable worker participation in setting objectives and giving support for achieving these if necessary.
NOTE A commonly used criteria is SMARTE (specific-measurable-achievable-reasonable-timely-ethical).
4.2.2.3 Examples
A nursing goal following the SMARTE criteria can be that a particular patient consumes at least 1,5 litres of
fluid every day starting on a certain date, and that this goal is reviewed daily.
At a financial bank, the workers task is to finish a fixed number of financial transactions (e.g. funds) monthly.
Every month, the attainability of this objective is reviewed by the worker and employer.
4.2.3 Extended reachability
4.2.3.1 Justification
If workers are available outside working hours, mental fatigue and burnout can occur.
4.2.3.2 Guideline
The designer should provide rules for extended reachability which are agreed upon and clearly
communicated and documented.
4.2.3.3 Examples
Rules can include the definition of time of non-availability, the ignoring of certain calls, the separation of
mail accounts into private and professional, the automation of mail sorting or the switch-off of notification
functions.
4.2.4 Flexibility in time allocation
4.2.4.1 Justification
In interaction work, working conditions should allow the worker to satisfy the needs of the interaction
partner (e.g. patients, and clients) in the given situation; otherwise, mental fatigue or burnout can occur.
4.2.4.2 Guideline
The designer should ensure that work systems allow flexibility in the time allocated to any task, especially
those requiring social interaction.
4.2.4.3 Example
A certain proportion of the daily working time can be set aside for disposable, as well as demand-oriented
interaction times.
ISO 10075-2:2024(en)
4.2.5 Definition of work-related services
4.2.5.1 Justification
If there are no definitions and clear descriptions of roles, the expectations between workers, clients and
management can differ and result in unnecessary work for the persons involved, leading to stress response
and mental satiation.
4.2.5.2 Guideline
The designer should define and document the scope and character of work or services and inherent tasks as
well as the roles and responsibilities.
4.2.5.3 Example
The description of a service can include, for example, information on the service objective, the period of
service provision and quality assurance measures.
4.2.6 Duration of working hours
4.2.6.1 Justification
The duration of working time influences the mental fatigue of workers. Mental fatigue can affect health,
safety and performance. The duration of working time should therefore be designed to prevent mental
fatigue.
4.2.6.2 Guidelines
The designer should:
— ensure that the duration of daily working time does not exceed 8 hours; however, an increase in the
duration of daily working time to 10 hours is acceptable if the average daily working time does not exceed
8 hours within a defined period;
— ensure that the duration of weekly working time does not exceed 48 hours; however, an increase in the
duration of weekly working time to 60 hours is acceptable if the average weekly working time does not
exceed 48 hours within a defined period;
— ensure that the duration of working time is reliable for the worker;
— involve workers in the planning of working time.
These are recommendations which the designer can apply in arranging working hours, taking the applicable
legal and regulatory requirements into consideration.
4.2.6.3 Examples
The designer can consider the introduction of working time accounts with time limits.
The designer can also consider compensation for overtime and extra work done in free time (rest time) in
the course of an agreed time period.
4.2.7 Time off between successive work days or shifts
4.2.7.1 Justification
The purpose of the time off between successive workdays or shifts (rest periods) is to allow workers to
recover. The rest period between successive shifts should be sufficient to allow full recovery from the mental

ISO 10075-2:2024(en)
fatigue of the previous shift. This is to ensure health, safety and performance and to prevent accidents
caused by exhaustion or lack of concentration.
4.2.7.2 Guidelines
The designer should:
— provide a rest period of at least 11 h between two shifts;
— design shift sequences to exclude the shortening, interruption and division of rest periods;
— allow an exceptional shortening of the rest period if there is a possibility of compensation within a fixed
period of time (e.g. within 4 weeks);
— keep the number of on-call duties during the workers' rest period as low as possible;
— limit the availability of workers during rest periods;
— consider monitoring adherence to rest periods (e.g. digital logbooks, time-recording systems);
— take account of secondary activities, such as travel time during business trips, when planning rest
periods.
4.2.7.3 Examples
The designer can consider reliable and comprehensible deployment planning with substitute regulations
and binding rest periods, developed with the participation of workers.
If not possible otherwise, the rest period can be shortened by a maximum of 1 h (e.g. in hospitals or care
facilities).
4.2.8 Time of day
4.2.8.1 Justification
Human bodily functions are subject to a natural 24 h day-night rhythm. The worker's performance fluctuates
during the working day. It is lower during the night than during the day. Activities during periods of low
performance are subject to higher risks to safety and health.
4.2.8.2 Guidelines
The designer should:
— consider circadian variations when planning working hours;
— reduce performance requirements during night hours compared with those during daytime work (more
breaks, fewer pieces, appropriate staff ratios in relation to task requirements).
4.2.8.3 Example
If atypical working hours are necessary, they should be:
— mutually agreed upon by the worker and the employer;
— made voluntary if possible;
— performed by a sufficient number of workers.

ISO 10075-2:2024(en)
4.2.9 Shift work
4.2.9.1 Justification
Shift work, especially night work, necessitates workers to perform work at a time when the organism or
body needs rest and time to recover due to natural circadian fluctuations. Such work can affect well-being,
present a risk to safety and health and have adverse social implications.
4.2.9.2 Guidelines
The designer should:
— rotate shifts forward on a rolling basis (early shift, late shift, night shift);
— adopt a short cycle (maximum 2 to 3 days) in planning shifts;
— keep the number of consecutive night shifts as low as possible (maximum three, but preferably only two
in a row);
— avoid permanent night shifts;
— involve workers in the planning of shift schedules.
4.2.9.3 Example
The early shift in the three-shift system should start at a time which allows workers in this shift sufficient
night sleep (e.g. later than 6 a.m.).
4.2.10 Breaks and rest pauses
4.2.10.1 Justification
Depending on the intensity, duration and temporal pattern of mental strain, mental fatigue (which is an
adverse and impairing effect) can occur.
4.2.10.2 Guideline
The designer should introduce planned breaks to provide opportunities for recuperation and maintain
efficiency and effectiveness.
4.2.10.3 Examples
Due to the exponential relation between the duration of uninterrupted work, mental fatigue and recovery,
short breaks after short periods of work are preferable to longer breaks after long periods of work. For
example, six short breaks of 5 min each after 55 min of work are preferable to one break of 30 min after 6 h of
work. Work or rest schedules for night work should feature shorter working periods than those of day work.
4.3 Design principles in relation to working tasks
4.3.1 Operating strategies
4.3.1.1 Justification
In complex situations, strategies, rules or operation procedures can facilitate decision-making and reduce
the likelihood of a stress response among workers.

ISO 10075-2:2024(en)
4.3.1.2 Guidelines
The designer should:
— provide a clear strategy for answering multiple requests in work systems where they need to be
answered;
— ensure the strategy to be used and the rules for following that strategy are clearly defined, for example
first-in-first-out, hierarchical or conditional;
— prefer a simple strategy, such as first-in-first-out to more complex strategies;
— ensure that the conditions for following conditional serving strategies are clearly understandable.
4.3.1.3 Examples
When providing first aid, there are specific rules concerning the order of medical measures.
Call-centre agents, too, can be given a strategy regarding which customer to take next. A first-in-first-out
strategy is often followed, although more complex strategies are sometimes adopted.
4.3.2 Continuous time constraints
4.3.2.1 Justification
Continuous time constraints can lead to shortcuts in task performance and, thus, to errors. If performance is
critical regarding its consequences, continuous time constraints can lead to mental fatigue, stress responses
or consequences in safety or the quality and quantity of work performance.
4.3.2.2 Guidelines
The designer should:
— minimize continuous time constraints;
— provide autonomy at work and ensure role clarity, including clarity of task objectives, to help to reduce
the impact of time constraints;
— consider the interplay of the different levels (such as organisation, team, task and worker) and support
from the management;
— consider the timing of tasks with time demands in relation to the available resources;
— prioritize tasks and reduce interruptions;
— provide resources for unforeseen events, where strict deadlines are necessary.
4.3.2.3 Examples
Successful project management necessitates the planning of work packages, taking into account
responsibility and time, in order to avoid time constraints.
4.3.3 Flexibility of decision-making
4.3.3.1 Justification
If there is no leeway in decision-making, it is possible that the goals of a work system will not be achieved.
Furthermore, the worker can experience a stress response, mental satiation or burnout as a long-term
consequence.
ISO 10075-2:2024(en)
4.3.3.2 Guideline
The designer should:
— provide flexibility in decision-making (decision latitude), where it is necessary to reach the objectives of
the work system;
— allocate additional resources for task performance within the scope of the decision-making process.
4.3.3.3 Example
A worker must repair a machine. There are several ways to repair the damage. Depending on the level of
knowledge, the worker can use any of these methods.
4.3.4 Ambiguity of task goals
4.3.4.1 Justification
If task goals are ambiguous, workers can decide the priority of goals for themselves. This can lead to a stress
response and inadequate task fulfilment, due to excessive demands or uncertainty about appropriate task
performance.
4.3.4.2 Guidelines
The designer should:
— define clear task goals;
— define the priority of different task goals when there are two or more goals;
— define task allocation between workers when there is more than one worker involved;
— provide social support in cases where ambiguous tasks cannot be avoided.
4.3.4.3 Examples
Agreements regarding the number of final quality inspections of a product without definition of the
motivating conditions (e.g. systematically low quality of individual components, failures in preceding
assembly or production slowdowns) can lead to ambiguity of task goals.
Ambiguity arises when there is a lack of clarity about the priority of tasks in relation to the objectives or a
lack of clarity regarding improving the quality over the quantity of the product.
4.3.5 Complexity of task requirements
4.3.5.1 Justification
If tasks are too complex, workers will possibly need to make too many decisions or decisions that are too
complicated, within a specific time interval, potentially resulting in a stress response. On the other hand,
tasks with a low level of complexity can lead to monotony or mental satiation.
4.3.5.2 Guidelines
The designer should:
— ensure that task complexity is at an optimal level, i.e. neither too low or too high;
— provide decision support systems where task complexity is too high;
— define clear task goals, including any task sub-goals.

ISO 10075-2:2024(en)
4.3.5.3 Example
In a control or emergency room environment, monitoring and responding to changes within a number of
parameters simultaneously can be challenging and can necessitate the prioritisation of requirements or the
provision of support.
4.3.6 Time sharing
4.3.6.1 Justification
If two or more tasks requiring attention are performed simultaneously, the limits of human processing
capacity can be exceeded. Important information can either be overlooked or the worker can become
mentally fatigued, or both.
4.3.6.2 Guidelines
The designer should:
— provide for a sequential task execution;
— prioritize tasks concerning their execution urgency;
— ensure that there are no interruptions during task execution.
4.3.6.3 Examples
Training with a simple and consistent stimulus-reaction assignment can be used for reducing attentional
demands. This only applies if the consequences of failures concerning erroneous information processing
have low relevance.
Follow-up alarms in the monitoring of flour bag filling quantities are identified as such in the control room
of a mill and marked for the worker. This makes it clear that the number of problems is not increasing.
In the control rooms
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