Glanceability Evaluation of a Physical Activity Feedback System

for Office Workers

S. T. Boerema

1,2

, R. Klaassen

, H. J. A. op den Akker

, H. J. Hermens

1,2

Roessingh Research and Development, Roessinghsbleekweg 33b,Enschede, the Netherlands

Telemedicine, University of Twente, P.O. Box 217 7500 AE, Enschede, the Netherlands

Human Media Interaction, University of Twente, P.O. Box 217 7500 AE, Enschede, the Netherlands

Keywords: Glanceability, Feedback, Physical Activity, User-centered Design, ICT Applications, Behaviour Change

Support System.

Abstract: This paper presents the results of a user evaluation to design a glanceable user interface presenting physical

activity feedback to office workers during the workday. The feedback is presented on a central and public

display next to the coffee machine in the office building. Users should be able to receive the feedback

quickly and easily while getting a cup of coffee − the user interface should be glanceable. The feedback

should communicate the (real-time) amount of physical activity and the progress toward the goal of the user

for a day. Three mock-ups of user interfaces were developed and evaluated in a user evaluation study.

Differences on reaction time and user preferences were found. None of these results were significant.

Adding group information to the mock-up increases reaction time and therefore lowers the glanceability

negatively.

1 INTRODUCTION

Not being sufficiently physically active is regarded

as one of the most important independent risk

factors of reduced life expectancy. It increases the

risk of obesity, coronary heart disease and stroke,

type 2 diabetes, as well as colon and breast cancer. It

is therefore recognised as one of the most important

modifiable risk factors that is causing the rising

global burden of chronic disease.

About 40% of Dutch adults are not sufficiently

physically active and over 40% are overweight or

obese. Studies showed pooled prevalence of

sedentary lifestyles for 15 European countries being

31%, whereas 17.7% of the population of 51 mainly

low- and middle-income worldwide countries were

physically inactive, indicating that inactivity may be

more prevalent in wealthier countries (Guthold et al.

2008). Many contemporary work tasks are

characterised by little or no physical activity. More

than a quarter of all employees in the Netherlands

have sedentary work and sit on average 4 hours

while being at work and travelling to and from work.

TNO Care and Prevention (Hildebrandt n.d.) states

that, in the Netherlands, employees that participate

in sports report less ill and mostly for a shorter

period then their non-sporting colleagues. This effect

is most strongly for employees with sedentary work.

Given the various health benefits of physical

activity, and the high prevalence of physical

inactivity during work, many health interventions

focus on promoting physical activity.

Providing feedback on the personal physical

activity level can create awareness and motivation to

change physical behaviour, as described in many

social cognitive models on health behaviour

(Nutbeam & Harris 2004). Physical activity

interventions focussed on sedentary workers have

been using self reporting methods (e.g.

questionnaires) and pedometers (i.e. step-counters)

(Chan et al. 2004; Dinger et al. 2007; Cocker et al.

2008). These studies provided feedback on an

individual level, not incorporating direct interference

of the social environment, while social norms are

often considered an important factor in behaviour

change, as described in the Health Belief Model, the

Social Cognitive Theory and the Theory of Planned

Behaviour (Rosenstock 1966; Bandura et al. 1977;

Ajzen 1991).

The office setting is an interesting environment

for studying group mechanisms in physical activity

feedback on the self-awareness and behaviour of

Boerema S., Klaassen R., Hermens H. and den Akker H. (2012).

Glanceability Evaluation of a Physical Activity Feedback System for Ofﬁce Workers.

In Proceedings of the Sixth International Symposium on e-Health Services and Technologies and the Third International Conference on Green IT

Solutions, pages 52-57

DOI: 10.5220/0004474000520057

 SciTePress

sedentary workers. To study these group

mechanisms, a system will be developed based on

wearable physical activity sensors and a feedback

device. We envision that the feedback device will be

used by multiple users in a public space of the office

containing personal and group feedback. This vision

implies high demands on the usability and

understanding of the graphical user interface (GUI)

of the feedback device. The goal of the system is to

create awareness and motivation people to be more

physical active, which can result in a healthier

lifestyle at the office. In this system, physical

activity is measured by a hip mounted activity

monitor – which can estimate energy expenditure

based on a 3D accelerometer according to the

method of Bouten (1996) – and this data is wireless

and real-time transmitted to and processed on a

central server. Based on the data the system presents

feedback on the central display of the system, which

is located near the coffee machine in the office

building. While waiting for their cup of coffee the

system shows real-time feedback about the physical

activity until that moment of the current workday.

The goal of this research is to design a user interface

to present feedback to the users on the central

display. Because of its setting at the coffee machine

the feedback interpretation time is limited. The

designed user interface should therefore be

glanceable. Matthews defines glanceable as follows:

"By glanceable, we mean enabling users to

understand information quickly and easily.

Glanceability is critical to peripheral display design

because users need to quickly glance at and read

displayed information with minimal interruption to

their primary task" (Matthews 2006; Matthews et al.

2007).

The effect on glanceability of various user

interfaces and the addition of group information to

personal feedback will be studied during a user

evaluation, in which reaction time will be used as a

measure for ‘quickly’ and the correctness of the

interpretation of the information in the mock-up as a

measurement for ‘easily’. From the results of the

user evaluation we conclude which of the designed

user interface is the most glanceable, what is the

effect of adding group information to user interface

on the glanceability, and which user interface is

preferred by the subjects.

2 METHODOLOGY

Three mock-ups of the envisioned physical activity

feedback system were compared in a controlled user

experiment to answer the research questions. To

measure the effect of glanceability the mock-ups

were compared using a within-subject design while

the effect of adding group information to the mock-

ups was compared in a between-subject design.

Personal information and information about

sitting behaviour, workday activities, physical

activity and sport are gathered at the beginning of

the experiment.

During the actual user experiment the participant

will evaluate the three mock-ups to measure the

clarity and glanceability of the mock-ups. Two

questions were given with each mock-up: one about

the amount of physical activity and one about the

progress towards their goal. The questions were the

same for all participants. Participants in the ‘with

group information’ group had to answer a third

question about their own performance compared to

the group performance. The participants can answer

the question on a five point Likert scale (1 for very

bad, to 5 for very good) and were asked to: “answer

the question correctly and as quickly as possible”.

The correctness of the interpretation is used to

calculate the clarity of the mock-up (whether the

answer is correct or not), while the reaction time

(the time the participant needs to answer the

question) is used to calculate the glanceability of the

mock-up. Incorrect answers were excluded from

reaction time calculations.

After each mock-up participants evaluated

usability and their perception of information on the

screen. This questionnaire was adapted from

Quesenbery (2003; Stone e.a. 2005) and was

extended by two questions on their intention to use

the system in future and the attractiveness of the

system.

At the end of the experiment the participants

were invited for a short, semi-structured interview

about their preference of one of the mock-ups and

their opinion on the general idea of presenting

feedback on physical activity on a public screen in

an office environment.

The results of the reaction times and the answers

to the questionnaire of the three mock-ups were

compared using a mixed between-within ANOVA

test. The results of the questionnaires were recorded

and interesting remarks will be presented in the

result section.

2.1 Subjects

Subjects were recruited from two offices by the

snowball sampling method. The only inclusion

criterion was: doing mainly deskwork.

Glanceability Evaluation of a Physical Activity Feedback System for Office Workers

Participants were randomly assigned to one of

two conditions: 1) presenting three mock-ups

without the group comparison (‘no group’) and 2)

presenting three mock-ups with the group

comparison (‘group’).

2.2 Procedure

The subjects were invited to participate in the

experiment. When the subjects agreed taking part in

the experiment they received a short written

introduction on physical activity and deskwork. The

introduction included a scenario in which the

envisioned system was introduced in an office

setting.

The order of presenting the three mock-ups was

counterbalanced. During the user evaluations the

participants were observed, notes were taken and

audio recordings of the interviews were stored.

Filling in the questionnaire and evaluating the mock-

ups were done on separate computers.

2.3 Design of Mock-ups

For both conditions three different mock-ups are a

Number, a Flower and a Graph. All user interfaces

present real-time physical activity data and the

progress of reaching the goal. In this the progress is

given in minutes of physical activity up to the

moment of walking by the feedback device and the

goal being a total of 30 minutes of physical activity

during office hours.

The first mock-up uses a number to present the

progress reaching the goal in a percentage (for

example 73%). The number presents the progress

towards the goal of the user. The background colour

presents how the user is distributing the amount of

activity over the day. Group information is added to

the mock-up by text stating the average score of the

group and the number of people that already reached

their goal.

The second mock-up uses a metaphor of a

growing flower to present the progress in physical

activity. The stage of the flower represents the

progress towards the goal of the user. The exact

percentage towards to the goal of the user is

displayed in the heart of the flower. Group

information is added to the mock-up by the

metaphor of a garden. Every flower represents a user

of the system. The garden provides an overview of

all the activities of all users.

The third mock-up presents physical activity of

the user in a graph. This mock-up is an improved

mock-up of the system and is based on the work of

Boerema (2009). The graph provides an overview of

the amount of physical activity per hour. Group

information is shown in the mock-up by a line that

shows the average level of physical activity of the

group. The six mock-ups are given in Figure 1.

No Group Group

Number

Flower

Graph Graph

Figure 1: Overview of the six mock-ups.

3 RESULTS

3.1 Subjects

Twenty seven people participated in the experiment.

From this, four were excluded from the data analysis

because they did not understand the experimental

setup, and expressed this during the experiment.

From the remaining 23 subjects, 12 were male and

11 female, with an average age of 31 ± 7 years.

The participants were all office workers

(researchers, administrative staff or undergraduate

students). They reported to have an average working

day of 8.1 ± 0.5 hours on which they spend on

average 7.1 ± 1.0 hours, sitting. On the question

whether they engage in sports, 14 subjects

responded positive, 3 negative, and 6 answered

‘rarely’, On the question whether the subject

considers himself or herself physically active above

EHST/ICGREEN 2012

the average, the response on a 5 point Likert scale:

not agree – agree, was 3 ± 1.2, which means that

they were neutral about their physical activity level

compared to others.

Twelve participants were assigned to the mock-

ups without the group comparison and 11

participants were assigned to the mock-ups with the

group comparison.

3.2 Intention to Use

After reading the scenario, participants rated their

intention to use the system, on a Likert scale 1-5:

negative – positive. They average response was 3.4

± 1.0, meaning that they were slightly positive on

using the system. There was no correlation between

the self reported engagement in sports, the physical

activity level and intention to use.

After each mock-up, intention to use was asked

again. Randomization of the mock-ups was tested by

studying order effects in intention to use. There was

no trend in intention to use answers neither towards

the positive nor the negative, therefore answers per

mock-up can be compared without correcting for the

order in which they were presented to the subject.

In both the ‘no group’ and ‘group’ conditions

comparison the intention to use was the lowest after

seeing the ‘Graph’: 2.5 ± 1.3. Intention to use after

‘Number’ was on average 3.3 ± 1.0 and after

‘Flower’, 2.8 ± 1.2. Only in the No Group condition

the intention to use after Flower was below 3, being

neutral. Results per condition are shown in Figure 2.

3.3 Correctness

In the ‘no group’ condition only one subject

answered ‘I don’t know’ while using the Graph

mock-up. In the ‘Group’ condition multiple subjects

answered ‘I don’t know’, three subjects while using

the Number mock-up, three subjects while using the

Flower mock-up and one subject while using the

Graph mock-up.

All information perception questions were

correctly answered, except for the ‘no group’ Flower

condition, which was mostly answered as showing

sufficient physical activity (while the flower

displayed a lower level of physical activity) and a

good progress towards the goal (while the flowers

displayed a bad progress towards their goal).

3.4 Reaction Time

The randomisation of the mock-ups was also tested

by studying order effect on reaction time. There was

Figure 2: Intention to use the system per condition

(‘No Group’ and ‘Group’), self reported on a 5 point

Likert scale: negative – positive. Self reports are given

after reading the scenario and after seeing each mock-up.

no order effect in reaction time for the questions,

indicating that reaction times can be compared

without correcting for the order in which subjects

have seen the mock-ups.

In figure 3 and 4 are the average reaction times

given per group, per mock-up. The reaction time on

question 2 (Q2) is in all cases much shorter than on

question 1 (Q1). For the first question the reaction

time is shorter for the No Group condition.

3.5 Interviews

At the end of the user evaluation the participants

indicated their preference for the mock-ups. Ten

participants preferred the Number, eight participants

preferred the Flower and five participants preferred

the Graph. The participants were asked to state their

opinion about presenting feedback in a public and

central place. Fifteen participants indicated that it

was no problem to show their physical activity level

on a central and public display. Eight participants

indicated that they have issues with the idea of

public and central feedback. These participants

expressed privacy concerns or were not interested at

all in these kinds of feedback systems. Nineteen

participants indicated that they would join a system

like this in their office, if it would be introduced.

4 DISCUSSION & CONCLUSION

The results of the user evaluation showed no

significant differences between the reaction times of

the different mock-ups. The Number and Graph

showed the shortest response time, see figure 3 and

4. These differences can be explained from the

design of the mock-ups. Presenting progress towards

Glanceability Evaluation of a Physical Activity Feedback System for Office Workers

Figure 3: Average reaction time and standard deviation of

question 1 about “sufficient physical activity”, given per

condition.

Figure 4: Average reaction time and standard deviation of

question 2 about “reaching the personal goal”, given per

condition.

a goal by displaying a percentage is one of the

simplest ways. Following the definition of

glanceability this should be the most glanceable user

interface. The Graph showed more details about the

amount of physical activity. It can take longer to

process the more detailed information. Using a

flower as a metaphor for displaying the amount of

physical activity is received as joyful, but less

intuitive for displaying the amount of physical

activity.

No significant differences were found between

the two conditions of ‘no group’ and ‘group’

feedback. The ‘no group’ condition showed a shorter

reaction time for all the participants on the first two

questions. This difference can be explained by the

extra time the user needs to interpret the extra

information of the group. Group information does

affect the correctness of the answer to the question

during the user evaluation. In the ‘group’ condition

only one participant was not able to answer a

question, while seven participants of the ‘group’

condition were not able to answer one of the

questions.

The results of interviews showed that the

participants preferred the ‘number’ mock-up. The

number is also most glanceable mock-up.

A small group of participants showed privacy

concerns of displaying public and central feedback

on a large screen in an office setting.

When designing a glanceable user interface for

the system, it should be taken into account if group

information is necessary to influence the user.

5 FUTURE WORK

A next step in designing a user interface for the

system is the personification of the user interface by

adding an embodied conversation (ECA) agent to

the user interface of the system. The results from

previous studies indicate that the use of an ECA can

have a positive effect on how the feedback is

received by the user in behaviour change support

systems. This can eventually lead to a better

performance of the coaching program in the future

and a more effective way to support users to change

their behaviour (Schulman & Bickmore 2009;

Blanson Henkemans et al. 2009; Berry et al. 2005).

The results of this user evaluation and the effect of

adding an ECA to the UI are subject of future user

evaluations with a working prototype of the system.

ACKNOWLEDGEMENTS

The authors would like to thank all subjects for

participating in this study.

The work of R. Klaassen en H. op den Akker

was funded by the European Commission, within the

framework of the ARTEMIS JU SP8 SMARCOS

project 100249 - (www.smarcos-project.eu).

The work of S. Boerema and H. Hermens was

funded by the SENIOR project, within the program

of economical innovation ‘Pieken in de Delta Oost-

Nederland’, The Netherlands.

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