Road vehicles — Transport information and control systems — Detection-response task (DRT) for assessing attentional effects of cognitive load in driving

ISO 17488:2016 provides a detection-response task mainly intended for assessing the attentional effects of cognitive load on attention for secondary tasks involving interaction with visual-manual, voice-based or haptic interfaces. Although this document focuses on the assessment of attentional effects of cognitive load (see Annex A), other effects of secondary task load may be captured by specific versions of the DRT, as further outlined in Annex B. Secondary tasks are those that may be performed while driving but are not concerned with the momentary real-time control of the vehicle (such as operating the media player, conversing on the phone, reading road-side commercial signs and entering a destination on the navigation system). NOTE According to this definition, secondary tasks can still be driving-related (such as in the case of destination entry). ISO 17488:2016 does not apply to the measurement of primary (driving) task demands related to the momentary real-time control of the vehicle, such as maintaining lane position and headway or responding to forward collision warnings. However, this does not preclude that the DRT method, as specified in this document, may be adapted to measure such effects. ISO 17488:2016 applies to both original equipment manufacturer (OEM) and after-market in-vehicle systems and to permanently installed, as well as portable, systems. It is emphasized that, while the DRT methodology defined in this document is intended to measure the attentional effects of cognitive load, it does not imply a direct relationship between such effects and crash risk. For example, taking the eyes off the road for several seconds in order to watch a pedestrian may not be very cognitively loading but could still be expected to strongly increase crash risk. Furthermore, interpret DRT results cautiously in terms of demands on a specific resource, such as cognitive load. Specifically, if the goal is to isolate the effect related to the cognitive load imposed by a secondary task on attention, avoid overlap with other resources required by the DRT (e.g. perceptual, motor, sensory or actuator resources). A particular concern derives from the fact that the DRT utilizes manual responses (button presses). Thus, for secondary tasks with very frequent manual inputs (on the order of one or more inputs per second), increased response times on the DRT may reflect this specific response conflict (which is due to the nature of the DRT) rather than the actual cognitive load demanded by the task when performed without the DRT (i.e. alone or during normal driving; see Annex E). Thus, for such response-intensive tasks, DRT results are interpreted with caution. This document defines three versions of the DRT and the choice of version depends critically on the purpose of the study and the conditions under which it is conducted (see Annexes A and B for further guidance on this topic). ISO 17488:2016 specifically aims to specify the detection-response task and the associated measurement procedures. Thus, in order to be applicable to a wide range of experimental situations, this document does not define specific experimental protocols or methods for statistical analysis. However, some guidance, as well as examples of established practice in applying the DRT, can be found both in the main body of this document and in the annexes (in particular Annexes C and E).

Véhicules routiers — Systèmes d'Information et de commande du transport — Tâche de Détection-Réponse (DRT) pour l'évaluation des effets attentionnels de la charge cognitive lors de la conduite

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Published
Publication Date
04-Oct-2016
Current Stage
9020 - International Standard under periodical review
Start Date
15-Oct-2021
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INTERNATIONAL ISO
STANDARD 17488
First edition
2016-10-01
Road vehicles — Transport
information and control systems
— Detection-response task (DRT)
for assessing attentional effects of
cognitive load in driving
Véhicules routiers — Systèmes d’Information et de commande du
transport — Tâche de Détection-Réponse (DRT) pour l’évaluation des
effets attentionnels de la charge cognitive lors de la conduite
Reference number
ISO 17488:2016(E)
ISO 2016
---------------------- Page: 1 ----------------------
ISO 17488:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland

All rights reserved. Unless otherwise specified, 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 the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 17488:2016(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Abbreviated terms .............................................................................................................................................................................................. 5

5 DRT methodology: Principles and overview ........................................................................................................................... 5

6 Measurement methods and procedures ...................................................................................................................................... 6

6.1 Participants ................................................................................................................................................................................................ 6

6.2 Experimental setup ............................................................................................................................................................................. 6

6.2.1 Non-driving experimental setup ........................................................................................................................ 6

6.2.2 Surrogate driving experimental setup .......................................................................................................... 6

6.2.3 Driving simulator experimental setup .......................................................................................................... 6

6.2.4 On-road experimental setup .................................................................................................................................. 6

6.3 Stimulus presentation....................................................................................................................................................................... 6

6.3.1 Stimulus presentation timing ............................................................................................................................... 7

6.3.2 Visual stimulus specifications .............................................................................................................................. 8

6.4 Response method ..............................................................................................................................................................................10

6.5 Primary driving task .......................................................................................................................................................................11

6.6 Instructions to participants ......................................................................................................................................................11

6.7 Training procedure ...........................................................................................................................................................................11

6.7.1 Secondary task training ..........................................................................................................................................12

6.7.2 DRT training ......................................................................................................................................................................12

6.7.3 Primary task training ................................................................................................................................................12

6.7.4 Training on multitasking .......................................................................................................................................12

6.8 Performance measures .................................................................................................................................................................12

6.9 Analysing and interpreting DRT performance data .............................................................................................13

6.10 Checking data quality .....................................................................................................................................................................13

6.11 Use of DRT data in decision making ..................................................................................................................................14

Annex A (normative) Rationale ..............................................................................................................................................................................15

Annex B (normative) Guidelines for selecting between variants of the DRT method ...................................23

Annex C (normative) Additional factors affecting DRT performance .............................................................................25

Annex D (informative) DRT variants .................................................................................................................................................................27

Annex E (informative) Summary of results from the ISO-coordinated studies .....................................................38

Bibliography .............................................................................................................................................................................................................................69

© ISO 2016 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 17488:2016(E)
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 documents 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).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on 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 the following URL: www.iso.org/iso/foreword.html.

The committee responsible for this document is ISO/TC 22, Road vehicles, Subcommittee SC 39,

Ergonomics.
iv © ISO 2016 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 17488:2016(E)
Introduction

Driving is a complex task consisting of a range of sub-tasks such as keeping the vehicle in the lane,

avoiding other traffic and obstacles, observing road signs and signals, planning and initiating specific

manoeuvres, scanning mirrors and navigating. In addition, drivers often engage in secondary tasks, not

directly related to driving, such as operating the media player, conversing on the phone and reading

road-side commercial signs.

These different activities place varying, and sometimes conflicting, demands on the driver. In order to

manage the various driving and secondary tasks, the driver thus needs to allocate different resources,

such as the eyes, hands, feet, perceptual systems, motor control systems and higher level cognitive

functions, to the different sub-tasks in a dynamic and flexible way. This allocation of resources to

driving and non-driving activities may be generally conceptualized as driver attention. In most driving

situations, attention is determined by an interaction of proactive (top-down, endogenous) processes

based on anticipation of how the upcoming situation will develop and bottom-up processes (driven by

exogenous stimuli) which can trigger attention to the situation when it does not develop as expected,

even leading to a corrective action.

There is a need for methods that can be used to assess how engagement in secondary tasks affects driver

attention. In general, the effect of a task on attention depends on the amount and type of resources

demanded by the task. As outlined in further detail in Annex A, resources can be conceptualized at

three general levels: sensory-actuator resources, perceptual-motor resources and cognitive resources.

Sensory/actuator resources refer to the basic interfaces between the driver and the environment used

to sense the environment and perform overt actions. Examples include the eyes, the ears, the skin, the

feet, the hands, the mouth, the vocal cords, etc. Perceptual/motor resources can be regarded as brain

functions for controlling specific perceptual-motor activities, e.g. visual perception, manual tracking

and hand-to-eye coordination. Finally, cognitive resources refer to brain systems implementing higher-

level cognitive operations such as planning, decision making, error detection, sustaining information

in working memory, dealing with novel or difficult situations and overcoming habitual actions. These

types of high-level cognitive functions may be conceptualized in terms of cognitive control. While

sensory-actuator and perceptual-motor resources are, at least to some extent, modality-specific,

cognitive control can be regarded as a single resource with strongly limited capacity, not associated

with any particular sensory modality. Cognitive load thus refers specifically to the demand for cognitive

control that a task imposes on the driver.

Several existing and draft ISO standards address the assessment of secondary task demand in the

[1] [2]

context of driving. ISO 15007-1 and ISO/TS 15007-2 provide guidance on how to measure glance

[3]

behaviour and ISO 16673 focuses exclusively on the viewing time required to perform a task using an

in-vehicle information system. Hence, these methods focus mainly on the assessment of (visual) sensory

[4]

demand (i.e. the demand for the eyes). ISO 26022 provides a technique for evaluating the combined

effect of sensory-actuator, perceptual-motor and cognitive demands on a driver’s performance in a

combined event detection and vehicle control task.

However, a standardized measurement method that specifically addresses cognitive load is lacking.

While, for example, ISO 26022 is sensitive to cognitive load, it lacks specificity since its main

performance metric (MDEV) is also sensitive to visual sensory motor interference (i.e. visual time

sharing; see Annex A). A standardized method specifically addressing cognitive load is particularly

needed in order to evaluate the attentional demands of new driver-vehicle interfaces designed to

minimize visual interaction such as voice-based interfaces, haptic input devices and head-up displays.

The detection-response task (DRT) method defined in this document intends to fill this gap. More

specifically, the DRT is mainly intended to measure effects of the cognitive load of a secondary task on

attention. However, some versions of the DRT specified in this document may also be used to capture

other forms of secondary task demand (e.g. visual sensory demand). The general rationale behind the

DRT methodology is further outlined in Annex A.

Annex B provides guidance on how to select among the different DRT versions defined in this

document. Annex C reviews factors that could potentially affect DRT performance and thus need to be

accounted for when designing DRT experiments. Annex D offers a review of existing alternative DRT

© ISO 2016 – All rights reserved v
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ISO 17488:2016(E)

methodologies not covered by this document. Annex E provides an overview of the results from a set of

coordinated studies with the purpose to support the development of this document. Finally, a general

bibliography is provided for existing DRT-related research.
vi © ISO 2016 – All rights reserved
---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 17488:2016(E)
Road vehicles — Transport information and control
systems — Detection-response task (DRT) for assessing
attentional effects of cognitive load in driving
1 Scope

This document provides a detection-response task mainly intended for assessing the attentional effects

of cognitive load on attention for secondary tasks involving interaction with visual-manual, voice-

based or haptic interfaces. Although this document focuses on the assessment of attentional effects of

cognitive load (see Annex A), other effects of secondary task load may be captured by specific versions of

the DRT, as further outlined in Annex B. Secondary tasks are those that may be performed while driving

but are not concerned with the momentary real-time control of the vehicle (such as operating the media

player, conversing on the phone, reading road-side commercial signs and entering a destination on the

navigation system).

NOTE According to this definition, secondary tasks can still be driving-related (such as in the case of

destination entry).

This document does not apply to the measurement of primary (driving) task demands related to

the momentary real-time control of the vehicle, such as maintaining lane position and headway or

responding to forward collision warnings. However, this does not preclude that the DRT method, as

specified in this document, may be adapted to measure such effects.

This document applies to both original equipment manufacturer (OEM) and after-market in-vehicle

systems and to permanently installed, as well as portable, systems.

It is emphasized that, while the DRT methodology defined in this document is intended to measure the

attentional effects of cognitive load, it does not imply a direct relationship between such effects and

crash risk. For example, taking the eyes off the road for several seconds in order to watch a pedestrian

may not be very cognitively loading but could still be expected to strongly increase crash risk.

Furthermore, interpret DRT results cautiously in terms of demands on a specific resource, such as

cognitive load. Specifically, if the goal is to isolate the effect related to the cognitive load imposed by a

secondary task on attention, avoid overlap with other resources required by the DRT (e.g. perceptual,

motor, sensory or actuator resources). A particular concern derives from the fact that the DRT utilizes

manual responses (button presses). Thus, for secondary tasks with very frequent manual inputs (on

the order of one or more inputs per second), increased response times on the DRT may reflect this

specific response conflict (which is due to the nature of the DRT) rather than the actual cognitive

load demanded by the task when performed without the DRT (i.e. alone or during normal driving;

see Annex E). Thus, for such response-intensive tasks, DRT results are interpreted with caution. This

document defines three versions of the DRT and the choice of version depends critically on the purpose

of the study and the conditions under which it is conducted (see Annexes A and B for further guidance

on this topic).

This document specifically aims to specify the detection-response task and the associated measurement

procedures. Thus, in order to be applicable to a wide range of experimental situations, this document

does not define specific experimental protocols or methods for statistical analysis. However, some

guidance, as well as examples of established practice in applying the DRT, can be found both in the main

body of this document and in the annexes (in particular Annexes C and E).
2 Normative references
There are no normative references in this document.
© ISO 2016 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO 17488:2016(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
actuator demand
demand for actuator resources (3.2) imposed by a task (3.30)
3.2
actuator resources
human body systems used to execute overt motor actions

Note 1 to entry: Examples of actuator resources include the hands, the feet, the vocal cords, etc.

3.3
attention

allocation of resources, encompassing both bottom up and top down attentional processes, to a

particular activity or activities
3.4
cognitive control

mental operations such as planning, decision making, error detection, inhibiting habitual actions,

utilizing information in working memory (3.36), and resolving novel and complex situations

3.5
cognitive resources
brain systems implementing cognitive control (3.4)
3.6
cognitive load
cognitive demand
demand for cognitive control (3.4) imposed by a task (3.30)
3.7
data segment
continuous portion of data
3.8
driver attention

allocation of resources (3.20), encompassing both bottom up and top down attentional processes, to

driving and/or non-driving-related activities
3.9
DRT stimulus

sensory signal controlled and issued to a participant during a DRT test session for the purpose of

eliciting a specified response (3.21)
3.10
hit

response (3.21) initiated within 100 ms to 2 500 ms from the stimulus onset (3.29), not preceded by an

earlier response in the same interval
Note 1 to entry: Hit is synonymous with valid response.
2 © ISO 2016 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 17488:2016(E)
3.11
hit rate

number of valid responses (3.33) divided by the total number of stimuli presented in a data collection

segment, excluding premature responses to stimuli
Note 1 to entry: See premature response (3.17).
3.12
missing response

absence of a response (3.21) within 100 ms to 2 500 ms after stimulus onset (3.29)

3.13
motor demand
demand for motor resources (3.13) imposed by a task (3.30)
3.14
motor resources
brain systems implementing the control of motor actions
3.15
perceptual demand
demand on perceptual resources (3.15) imposed by a task (3.30)
3.16
perceptual resources
brain systems implementing perception

Note 1 to entry: Perceptual functions include lower-level, modality-specific perception (e.g. visual and auditory

perception), as well as higher-level cross-modal perceptual integration.
3.17
premature response

response (3.21) initiated within 100 ms from the stimulus onset (3.29), prior to the timing interval for a

valid response (3.33)
3.18
primary task

driving or driving-like task (3.30) used in the surrogate driving, driving simulator or on-road DRT

experimental setups
3.19
repeated response

response (3.21) initiated within 100 ms to 2 500 ms after the stimulus onset (3.29) that is preceded by

an earlier response in the same interval
3.20
resources
systems in the brain or body that can be utilized to perform tasks (3.30)
3.21
response
signal generated by the participant pressing the response button
3.22
response time
time from the stimulus onset (3.29) until the response onset
Note 1 to entry: Response time is only defined for valid responses.
© ISO 2016 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO 17488:2016(E)
3.23
secondary task

task (3.30) that may be performed while driving but that is not concerned with the momentary real-

time control of the vehicle

Note 1 to entry: Examples include operating the media player, conversing on the phone, reading road-side

commercial signs and entering a destination on the navigation system. Thus, secondary tasks may be driving-

related.
3.24
sensory demand
demand on sensory resources (3.24) imposed by a task (3.30)
3.25
sensory resources

human body systems used to sense the exterior environment or internal bodily states

Note 1 to entry: Examples of sensory resources include the eyes, the ears, the skin, etc.

3.26
stimulus duration
time during which the stimulus is turned on
Note 1 to entry: The maximum stimulus duration is set at 1 s.

Note 2 to entry: Stimulus duration depends on responses. The maximum stimulus duration represents the pre-

set duration of the stimulus in the absence of a response. If the response is initiated prior to maximum stimulus

duration, the stimulus is turned off.
3.27
stimulus cycle period
time from the onset of a stimulus until the onset of the next stimulus
3.28
stimulus offset
point in time when the DRT stimulus (3.9) is turned off
3.29
stimulus onset
point in time when the DRT stimulus (3.9) is turned on
3.30
task
process of achieving a specific and measurable goal using a prescribed method
3.31
trial
test of one participant undertaking one secondary task (3.23) one time
3.32
unrequested response
response (3.21) given later than 2 500 ms after the stimulus onset (3.29)
3.33
valid response

response (3.21) initiated within 100 ms to 2 500 ms from the stimulus onset (3.29), not preceded by an

earlier response in the same interval
Note 1 to entry: Valid response is synonymous with hit.
4 © ISO 2016 – All rights reserved
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ISO 17488:2016(E)
3.34
visual angle

angle subtended at the eye by a viewed object or separation between viewed objects

Note 1 to entry: Measurement of visual angle is made edge to edge.
3.35
visual eccentricity

visual angle (3.34), relative to the centre of the fovea, at which a certain visual stimulus impinges on

the retina

Note 1 to entry: Measurement of visual eccentricity is made from centre of eye to centre of visual stimulus.

3.36
working memory

executive and attentional aspect of short-term memory involved in the interim integration, processing,

disposal and retrieval of information
4 Abbreviated terms
ANOVA analysis of variance
B baseline
DRT detection-response task
HDRT head-mounted DRT
HR hit rate
MR miss rate
N0 0-Back
N1 1-Back
OEM original equipment manufacturer
R response
RT response time
RDRT remote DRT
SE easy SuRT
SH hard SuRT
TDRT tactile DRT
5 DRT methodology: Principles and overview

The DRT method is based on a simple detection-response task where participants respond to relatively

frequent artificial stimuli presented with a specified degree of temporal uncertainty. Detection

performance, measured in terms of response time and hit rate, is assumed to represent the degree to

which attention is affected by the demand and, in particular, the cognitive load component imposed

by the secondary task under evaluation. Longer reaction times and reduced hit rate are indicative of

higher cognitive load.
© ISO 2016 – All rights reserved 5
---------------------- Page: 11 ----------------------
ISO 17488:2016(E)

The method may be implemented in several different ways, depending on the purpose of the study.

The DRT versions specified by this document differ in terms of stimulus presentation modality and

experimental setup, as further described below.
6 Measurement methods and procedures
6.1 Participants

Participants should be licensed drivers with a similar level of prior experience with the secondary task

under evaluation. Other relevant characteristics of the participants shall be recorded, including at least

driving experience (e.g. miles or km driven in the last year), similar device use experience, gender, age

and previous experience with the DRT.
6.2 Experimental setup
The DRT may be used in different experimental setups as described below.
6.2.1 Non-driving experimental setup

In this setup, the DRT is performed concurrently with the secondary task under evaluation in a non-

driving situation. This means that attention is divided between the secondary task under evaluation

and the DRT, without simultaneous performance of a primary (driving or driving-like) task. DRT

performance with the secondary task is assessed relative to a baseline condition where only the DRT

is performed. The non-driving version of the DRT may be used to assess how a secondary task affects

selective attention in any non-driving setting, including production vehicles, vehicle mock-ups or at a

desktop.
6.2.2 Surrogate driving experimental setup

In this setup, the DRT is performed concurrently with the secondary task under evaluation while the

participant performs a surrogate task that functions as the primary task of driving. This surrogate

task could be a simple tracking task, watching a video of real-world driving recorded from the driver’s

viewpoint or a combination of such elements. DRT performance during the combined secondary task

and surrogate driving is assessed relative to a baseline condition where the DRT is performed with only

the surrogate driving task.
6.2.3 Driving simulator experimental setup

In this setup, the DRT is performed concurrently with the secondary task under evaluation while the

participant drives a driving simulator. DRT performance during the combined secondary task and

simulator driving is assessed relative to a baseline condition where the DRT is performed while only

driving the simulator. The same scenario is used in both conditions.
6.2.4 On-road experimental setup

In this setup, the DRT is performed concurrently with the secondary task under evaluation while the

participant drives on a closed track or an open road with traffic. Appropriate safety concerns shall be

addressed for on-road testing. DRT performance during the combined secondary task and driving is

assessed relative to a baseline condition where the DRT is performed while only driving.

6.3 Stimulus presentation

This document specifies three alternative methods for presenting the DRT stimulus. This includes two

methods where the stimulus is presented visually and one method where the stimulus is provided by

means of tactile stimulation. In the head-mounted DRT (HDRT), a visual stimulus (an LED) is presented

through a fixture attached to the head of the participant at a specified visual angle. In the remote

DRT (RDRT), a visual stimulus (e.g. an LED or embedded graphic in simulator scenario) is presented

6 © ISO 2016 – All rights reserved
---------------------- Page: 12 ----------------------
ISO 17488:2016(E)

in the forward view of the participant. Finally, in the tactile DRT (TDRT), a tactile vibrator is placed

on the participant’s body. These stimulus presentation methods are described in further detail below.

Guidelines for the selection of stimulus presentation mode depend on the purpose of the experiment

and are provided in Annex B.
6.3.1 Stimulus presentation timing
The stimulus presentation timing is the same for all three stimul
...

DRAFT INTERNATIONAL STANDARD ISO/DIS 17488
ISO/TC 22/SC 13 Secretariat: AFNOR
Voting begins on Voting terminates on
2015-04-06 2015-07-06

INTERNATIONAL ORGANIZATION FOR STANDARDIZATION  МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ  ORGANISATION INTERNATIONALE DE NORMALISATION

Road vehicles — Transport information and control systems —
Detection-Response Task (DRT) for assessing attentional
effects of cognitive load in driving
Véhicules routiers — Systèmes de commande et d'information du transport
ICS 35.240.60; 43.040.15

To expedite distribution, this document is circulated as received from the committee

secretariat. ISO Central Secretariat work of editing and text composition will be undertaken at

publication stage.

Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du

secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au

Secrétariat central de l'ISO au stade de publication.

THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE

REFERRED TO AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH.

IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES,

DRAFT INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME

STANDARDS TO WHICH REFERENCE MAY BE MADE IN NATIONAL REGULATIONS.

RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT, WITH THEIR COMMENTS, NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OF WHICH

THEY ARE AWARE AND TO PROVIDE SUPPORTING DOCUMENTATION.
© International Organization for Standardization, 2015
---------------------- Page: 1 ----------------------
ISO/DIS 17488
COPYRIGHT PROTECTED DOCUMENT
© ISO 2015

All rights reserved. Unless otherwise specified, 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 the internet or an intranet, without prior written permission.

Permission can be requested from either ISO at the address below or ISO’s member body in the country of the requester.

ISO copyright office
Case postale 56  CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2015 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/DIS 17488
Contents Page

Foreword ............................................................................................................................................................. v

Introduction ........................................................................................................................................................ vi

1 Scope ...................................................................................................................................................... 1

2 Normative references ............................................................................................................................ 1

3 Terms and definitions ........................................................................................................................... 2

4 Abbreviations ......................................................................................................................................... 5

5 The DRT methodology: Principles and overview ............................................................................... 5

6 Measurement methods and procedures ............................................................................................. 5

6.1 Participants ............................................................................................................................................ 5

6.2 Experimental setup ............................................................................................................................... 5

6.3 Stimulus presentation ........................................................................................................................... 6

6.4 Response method ............................................................................................................................... 10

6.5 Primary driving task ............................................................................................................................ 10

6.6 Instructions to participants ................................................................................................................ 11

6.7 Training procedure .............................................................................................................................. 11

6.8 Performance measures ....................................................................................................................... 12

6.9 Analysing and interpreting DRT performance data ......................................................................... 12

6.10 Checking data quality ......................................................................................................................... 13

Annex A (normative) Rationale ...................................................................................................................... 14

A.1 Introduction .......................................................................................................................................... 14

A.2 Driver attention .................................................................................................................................... 14

A.3 Resource demands and task interference ........................................................................................ 15

A.4 Resource demands and task interference for the DRT ................................................................... 18

A.5 Adaptive driver behaviour and resource allocation strategies ...................................................... 19

A.6 Conclusions ......................................................................................................................................... 21

Annex B (normative) Guidelines for selecting between variants of the DRT method.............................. 22

B.1 Introduction .......................................................................................................................................... 22

B.2 Auditory-vocal tasks ........................................................................................................................... 22

B.3 Visual tasks .......................................................................................................................................... 23

B.4 Tasks involving manual interaction .................................................................................................. 23

B.5 Practical considerations ..................................................................................................................... 23

Annex C (normative) Additional factors affecting DRT performance ........................................................ 24

C.1 Introduction .......................................................................................................................................... 24

C.2 Vehicle type and dynamics................................................................................................................. 24

C.3 Road type ............................................................................................................................................. 24

C.4 Road conditions .................................................................................................................................. 24

C.5 Traffic density ...................................................................................................................................... 24

C.6 Lighting conditions ............................................................................................................................. 24

C.7 Visibility ................................................................................................................................................ 24

Annex D (informative) DRT Variants ............................................................................................................. 25

D.1 Introduction .......................................................................................................................................... 25

D.2 DRT taxonomy by input modality ...................................................................................................... 25

D.3 Development and description for each DRT..................................................................................... 26

D.4 Compendium of DRT development, implementation and citations ............................................... 27

Annex E (informative) Summary of results from the ISO coordinated studies ........................................ 35

E.1 Introduction .......................................................................................................................................... 35

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E.2 Key Research Questions ................................................................................................................... 35

E.3 Methods ............................................................................................................................................... 35

E.4 RT Results (Questions 1-3) ................................................................................................................ 38

E.5 Discussion of results for RT (questions 1 to 3) ............................................................................... 46

E.6 Analysis of hits and misses in ISO DRT cross-site studies (Question 4) ..................................... 50

E.7 General Discussion ............................................................................................................................ 61

E.8 General conclusions to ISO coordinated studies ........................................................................... 63

E.9 RT data ................................................................................................................................................. 64

Bibliography ..................................................................................................................................................... 69

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ISO/DIS 17488
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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 17488 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 13,

Ergonomics applicable to road vehicles.

This second/third/... edition cancels and replaces the first/second/... edition (), [clause(s) / subclause(s) /

table(s) / figure(s) / annex(es)] of which [has / have] been technically revised.

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Introduction

Driving is a complex task consisting of a range of sub-tasks such as keeping the vehicle in the lane, avoiding

other traffic and obstacles, observing road signs and signals, planning and initiating specific manoeuvres,

scanning mirrors, and navigating. In addition, drivers often engage in secondary tasks, not directly related to

driving, such as operating the media player, conversing on the phone and reading road-side commercial

signs.

These different activities place varying, and sometimes conflicting, demands on the driver. In order to manage

the various driving and secondary tasks, the driver thus needs to allocate different resources such as the

eyes, hands, feet, perceptual systems, motor control systems and higher level cognitive functions, to the

different sub-tasks in a dynamic and flexible way. This allocation of resources to driving and non-driving

activities may be generally conceptualized as driver attention. In most driving situations, attention is largely

proactive (top-down, endogenous) based on anticipation of how the upcoming situation will develop. However,

when the situation does not develop as expected, reactive (bottom-up, exogenous) attention is needed to

trigger corrective action.

There is a need for methods that can be used to assess how engagement in secondary tasks affects driver

attention. In general, the effect of a task on attention depends on the amount and type of resources demanded

by the task. As outlined in further detail in Annex A, resources can be conceptualised at three general levels:

(1) sensory-actuator resources, (2) perceptual-motor resources and (3) cognitive resources. Sensory/actuator

resources refer to the basic interfaces between the driver and the environment used to sense the environment

and perform overt actions. Examples include the eyes, the ears, the skin, the feet, the hands, the mouth, the

vocal cords, etc. Perceptual/motor resources can be regarded as brain functions for controlling specific

perceptual-motor activities, for example visual perception, manual tracking and hand-to-eye coordination.

Finally, cognitive resources refer to brain systems implementing higher-level cognitive operations such as

planning, decision making, error detection, sustaining information in working memory, dealing with novel or

difficult situations and overcoming habitual actions. These types of high-level cognitive functions may be

conceptualized in terms of cognitive control. While sensory-actuator and perceptual-motor resources are, at

least to some extent, modality-specific, cognitive control can be regarded as a single resource with strongly

limited capacity, not associated with any particular sensory modality. Cognitive load thus refers specifically to

the demand for cognitive control that a task imposes on the driver.

Several existing and draft ISO standards address the assessment of secondary task demand in the context of

driving. ISO 15007-1 and ISO/TS 15007-2 (Measurement of Driver Visual Behaviour) provide guidance on

how to measure glance behaviour, and ISO 16673 (Occlusion Method to Assess Visual Distraction) focuses

exclusively on the viewing time required to perform a task using an in-vehicle information system. Hence,

these methods focus mainly on the assessment of (visual) sensory demand (i.e., the demand for the eyes).

ISO 26022 (Simulated Lane Change Test) provides a technique for evaluating the combined effect of sensory-

actuator, perceptual-motor and cognitive demands on a driver’s performance in a combined event-detection-

and-vehicle-control-task.

However, a standardised measurement method that specifically addresses cognitive load is lacking. While, for

example, ISO 26022 (Simulated Lane Change Test) is sensitive to cognitive load, it lacks specificity since its

main performance metric (MDEV) is also sensitive to visual sensory motor interference (i.e., visual time

sharing; see Annex A). A standardised method specifically addressing cognitive load is particularly needed in

order to evaluate the attentional demands of new driver-vehicle interfaces designed to minimise visual

interaction such as voice-based interfaces, haptic input devices and head-up displays.

The Detection Response Task (DRT) method defined by the present standard intends to fill this gap. More

specifically, the DRT is mainly intended to measure effects of the cognitive load of a secondary task on

attention. However, some versions of the DRT specified by this standard may also be used to capture other

forms of secondary task demand (e.g., visual sensory demand). The general rationale behind the DRT

methodology is further outlined in Annex A.
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Annex B provides guidance for how to select between the different DRT versions defined in the standard.

Annex C reviews factors that could potentially affect DRT performance and thus needs to be accounted for

when designing DRT experiments. Annex D offers a review of existing alternative DRT methodologies not

covered by this standard. Annex E provides an overview of the results from a set of coordinated studies with

the purpose to support the development of the standard. Finally, Annex F provides a general bibliography for

existing DRT-related research.
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DRAFT INTERNATIONAL STANDARD ISO/DIS 17488
Road vehicles — Transport information and control systems —
Detection-Response Task (DRT) for assessing attentional
effects of cognitive load in driving
1 Scope

This standard provides a Detection Response Task mainly intended for assessing the attentional effects of

cognitive load on attention for secondary tasks involving interaction with visual-manual, voice-based, or haptic

interfaces. Although the standard focuses on the assessment of attentional effects of cognitive load (see

Annex A), other effects of secondary task load may be captured by specific versions of the DRT, as further

outlined in Annex B. Secondary tasks are those that may be performed while driving but are not concerned

with the momentary real-time control of the vehicle (such as operating the media player, conversing on the

phone, reading road-side commercial signs and entering a destination on the navigation system).

Note 1 to entry: According to this definition, secondary tasks may still be driving-related (such as in the case of

destination entry).

The standard does not apply to the measurement of primary (driving) task demands related to the momentary

real-time control of the vehicle, such as maintaining lane position and headway, or responding to forward

collision warnings. However, this does not preclude that the DRT method, as specified in this standard, may

be adapted to measure such effects.

This standard applies to both Original Equipment Manufacturer (OEM) and After-Market in-vehicle systems,

and to permanently installed as well as portable systems.

It should be emphasized that, while the DRT methodology defined in this international standard is intended to

measure the attentional effects of cognitive load, it does not imply a direct relationship between such effects

and crash risk. For example, taking the eyes off the road for several seconds in order to watch a pedestrian

may not be very cognitively loading but could still be expected to strongly increase crash risk.

Furthermore, caution is needed when interpreting DRT results in terms of demands on a specific resource,

such as cognitive load. Specifically, if the goal is to isolate the effect related to the cognitive load imposed by a

secondary task on attention, care must be taken to avoid overlap with other resources required by the DRT

(e.g., perceptual, motor, sensory or actuator resources). A particular concern derives from the fact that the

DRT utilises manual responses (button presses). Thus, for secondary tasks with very frequent manual inputs

(on the order of one or more inputs per second), increased response times on the DRT may reflect this

specific response conflict (which is due to the nature of the DRT) rather than the actual cognitive load

demanded by the task when performed without the DRT (i.e., alone or during normal driving; see Appendix E).

Thus, for such response-intensive tasks, DRT results should be interpreted with caution. The present standard

defines three versions of the DRT and the choice of version depends critically on the purpose of the study and

the conditions under which it is conducted (see Annex A and Annex B for further guidance on this topic).

This standard specifically aims to specify the Detection Response Task and the associated measurement

procedures. Thus, in order to be applicable to a wide range of experimental situations, the standard does not

define specific experimental protocols or methods for statistical analysis. However, some guidance, as well as

examples of established practice in applying the DRT, can be found both in the main body of the standard and

in the Annexes (in particular Annex C and Annex E).
2 Normative references
There are no normative references for this standard.
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3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
Actuator demand
demand for actuator resources imposed by a task
3.2
Actuator resources
Human body systems used to execute overt motor actions

Note 1 to entry: Examples of actuator resources include the hands, the feet, the vocal cord etc.

3.3
attention
see driver attention
3.4
cognitive control

mental operations such as planning, decision making, error detection, inhibiting habitual actions, utilizing

information in working memory, and resolving novel and complex situations
3.5
cognitive resources
brain systems implementing cognitive control
3.6
cognitive load/demand
demand for cognitive control imposed by a task
3.7 data segment
continuous portion of data
3.8
driver attention
allocation of resources to driving or non-driving-related activities
3.9
hit rate

number of valid responses divided by the total number of stimuli presented in a data segment, excluding

stimuli responded to prematurely (see premature response)
3.10
missing response
no response is given within 100 - 2 500 ms after stimulus onset
3.11
motor demand
demand for motor resources imposed by a task
3.12
motor resources
brain systems implementing the control of motor actions
3.13
perceptual demand
demand on perceptual resources imposed by a task
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3.14
perceptual resources
brain systems implementing perception

Note 1 to entry: Perceptual functions include lower-level, modality-specific perception (e.g., visual and auditory

perception) as well as higher-level cross-modal perceptual integration.
3.15
premature response
response initiated within 100 ms from the stimulus onset
3.16
primary task

driving or driving-like task used in the surrogate driving, driving simulator or on-road DRT experimental set-

ups
3.17
repeated response

response given within 100 – 2 500 ms after the stimulus onset that is preceded by another response in the

same interval
3.18
resources
systems in the brain or body that can be utilised to perform tasks
3.19
response
signal generated by the participant pressing the response button
3.20
response time
time from the stimulus onset until the response onset
Note 1 to entry: Response time is only defined for valid responses.
3.21
secondary task

task that may be performed while driving but that is not concerned with the momentary real-time control of the

vehicle

Note 1 to entry: Examples include operating the media player, conversing on the phone, reading road-side commercial

signs and entering a destination on the navigation system. Thus, secondary tasks may be driving-related.

3.22
sensory demand
demand on sensory resources imposed by a task
3.23
sensory resources

human body systems used to sense the exterior environment or internal bodily states

Note 1 to entry: Examples of sensory resources include the eyes, the ears, the skin etc.

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3.24
stimulus duration
time during which the stimulus is turned on

Note 1 to entry: Stimulus duration depends on responses. The maximum stimulus duration represents the pre-set

duration of the stimulus in the absence a response. If the response is initiated prior to maximum stimulus duration, the

stimulus is turned off.
3.25
stimulus cycle period
time from the onset of a stimulus until the onset of the next stimulus
3.26
stimulus offset
point in time when the DRT stimulus is turned off
3.27
stimulus onset
point in time when the DRT stimulus is turned on
3.28
task
process of achieving a specific and measurable goal using a prescribed method
3.29
trial
test of one participant undertaking one secondary task one time
3.30
unrequested response
a response given later than 2 500 ms after the stimulus onset
3.31
valid response

response initiated within 100 – 2 500 ms from the stimulus onset and not preceded by an earlier response in

the same interval
3.32
visual angle

angle subtended at the eye by a viewed object or separation between viewed objects

3.33
visual eccentricity

visual angle, relative to the centre of the fovea, at which a certain visual stimulus impinges on the retina

3.34
working memory

executive and attentional aspect of short-term memory involved in the interim integration, processing,

disposal, and retrieval of information
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ISO/DIS 17488
4 Abbreviations
B Baseline
DRT Detection Response Task
DRV Dual Remote Visual
HDRT Head mounted DRT
HR Hit Rate
MR Miss Rate
N0 0-Back
N1 1-Back
OEM Original Equipment Manufacturer
R Response
RT Response Time
RDRT Remote DRT
SE Easy SuRT
SH Hard SuRT
TDRT Tactile DRT
5 The DRT methodology: Principles and overview

The DRT method is based on a simple detection-response task where participants respond to relatively

frequent artificial stimuli presented with a specified degree of temporal uncertainty. Detection performance,

measured in terms of response time and hit rate, is assumed to represent the degree to which attention is

affected by the demand, and in particular the cognitive load component imposed by the secondary task under

evaluation. Longer reaction times and reduced hit rate are indicative of higher cognitive load.

The method may be implemented in several different ways, depending on the purpose of the study. The DRT

versions specified by this standard differ in terms of (1) stimulus presentation modality and (2) experimental

set-up, as further described below.
6 Measurement methods and procedures
6.1 Participants

Participants should be licensed drivers with a similar level of prior experience with the secondary task under

evaluation. Other relevant characteristics of the participants shall be recorded, including at least driving

experience (e.g., miles or km driven in the last year), similar device use experience, gender, age and previous

experience with the DRT.
6.2 Experimental setup
The DRT may be used in different experimental set-ups as described below.
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6.2.1 Non-driving experimental set-up

In the non-driving experimental set-up, the DRT is performed concurrently with the secondary task under

evaluation in a non-driving condition. This means that attention is divided between the secondary task under

evaluation and the DRT, without simultaneous performance of a primary (driving- or driving-like) task.

Performance is compared to a baseline condition where the DRT is performed alone. The non-driving version

of the DRT may be used to assess how a secondary task affects selective attention in any non-driving setting,

including production vehicles, vehicle mock-ups or at a desktop.
6.2.2 Surrogate driving experimental set-up

In the surrogate driving experimental set-up, the DRT is performed concurrently with the secondary task under

evaluation and some primary task elements that function as a surrogate for driving. This surrogate primary

task could be a simple tracking task, watching a video of real-world driving, recorded from the driver’s

viewpoint, or a combination of such elements. DRT performance with a secondary task under evaluation is

compared to a baseline condition where the DRT is performed concurrently with the surrogate primary task.

6.2.3 Driving simulator experimental set-up

In the driving simulator experimental set-up, the DRT, secondary task, and driving task are executed

concurrently. In this experimental set-up, DRT performance with a secondary task under evaluation is

assessed relative to a baseline condition where the DRT is performed whi
...

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