-
INTRODUCTION
Overweight and obesity, especially in the younger population,
are major health concerns worldwide (WHO, [
34
]).
According to a European statistic more than 60% of children that are
affected by overweight before puberty will maintain weight in
young adulthood (WHO, [
33
]).
The interdisciplinary enable-cluster is one of four clusters
about nutrition research funded by the German Federal
Ministry of Education and Research (BMBF) [
14
]. In one of its
core projects, enable investigates digital communication
strategies to improve nutrition behavior. As a result, the NUDGE
system is designed as an educative and preventive tool for
adolescents to impart nutritional knowledge in a playful and
motivational setting. To reach this goal, it promotes health-related
outcomes using serious games [
1
] and different persuasive
elements [
27
].
Besides the imparting of nutritional knowledge, NUDGE tries
to accompany its users by creating positive feedback loops
using both automated and real world input to ensure the users
feel comfortable with their behavioral changes.
PREVIOUS WORK ON HEALTH GAMES
There have been several studies on different types of games
for health and fitness. [
3
] reviewed 25 video games and found
that they were split into different outcomes such as knowledge
increase and changes in attitude and behavior. Since NUDGE
wants to encompass a holistic approach the following six well
cited serious games were reviewed regarding their persuasive
strategies and health-related goals.
One of the first digital nutritional games, ’Packy & Marlon’,
was designed for children and adolescents with diabetes [
8
].
The playing children had to manage the blood glucose levels
of two elephants with diabetes by choosing adequate food and
insulin quantities. A six-month randomized controlled trial
(n=59; age=8-16 years) showed that after playing the user’s
knowledge about diabetes increased, while the amount of
urgent hospital visits decreased.
The game ’HungryRedPlanet’ [
2
] (age=10-15 years) used
a similar approach for healthy adolescents by utilizing the
USDA (U.S. Department of Agriculture) Pyramid Guide for
a healthy and balanced nutrition. Similar to the game ’Packy
& Marlon’, the goal of this game is to manage adequate food
quantities to win the game and stop earths starvation.
The two serious games ’Escape from Diab’ (2010) [
32
]
(age=10-12 years) and ’PLAY, MATE!’ (2010) [
4
] (n=180;
age=9-12 years) focused on persuasion and behavior change
in addition to the knowledge transfer. The study of [
4
] showed
that games and persuasive elements could increase the
physical activity without disturbing the enjoyment of players.
More health games are starting to integrate different persuasive
concepts to address different target groups. For example, the
National Mindless Eating Challenge (NMEC) [
19
] (n=2053;
age=39,8 years in average) integrated comparisons,
customization, rewards, personalization and suggestions. Finally, the
game ’Move2Play’ [
5
] (n=12; age=12-13 years) provides a
setup for physical activity similar to the one NUDGE is
implementing for nutrition. They integrated monitoring,
goalsetting, a social component, achievements, rewards, and an
avatar component. Their small study showed, that the
children were able to understand all different components of the
setup and enjoyed the customizing of the avatar and the social
components.
CONCEPTS OF GAMES FOR HEALTH
In addition to the games review, different theoretical
approaches influenced the design of the NUDGE platform. The
concept of serious gaming was applied to derive mini-games
for nutritional knowledge and skill transfer. The theory of
persuasive gaming was used to develop the interaction of the
platform such as the avatar and the notification system. The
concept of positive gaming was applied to furthermore
improve the user’s wellbeing during his behavior change.
Serious Gaming
Gamification as a preventive tool for promoting health-related
behaviors often lacks in efficacy. It mainly transfers game
elements such as points or leaderboards to a non-gaming
content [
12
]. In contrast to gamification, serious games offer
the possibility for an active exploration of serious intellectual
problems [
1
]. For example, a gamification approach would
be to give the user achievements, when he fills his nutritional
diary. A serious game however would incorporate the
nutritional knowledge and offer activities, that will transfer that
knowledge actively to the user. At the same time the gaming
character is stimulating the user’s intrinsic motivation to play
and to learn [
36
]. The primary purpose of a serious game is
to transfer knowledge in a playful gaming context [
11
]. The
NUDGE platform uses the concepts of serious gaming and
motivational stimulation in different nutritional mini-games.
Persuasive Gaming
Persuasive strategies are application components that are
designed to influence the user’s behavior or attitude towards a
predefined goal [
16
]. [
27
] defined a framework with 28
different persuasive strategies. [
35
] reviewed the implementation of
those different strategies in 44 papers from different domains.
For the health domain, they came up with the following ten
most used strategies: feedback, self-monitoring, suggestion,
social role, simulation, tailoring, tunneling, reminders,
reduction, and reward.
There are drawbacks to some of these strategies regarding their
applicability to all user groups. Some strategies only work for
specific selection of personality types. [
28
] and [
20
] describe
how using generic persuasive strategies might even reverse the
motivational effect for specific personality types. However,
strategies such as competition, comparison, self-monitoring
and suggestion seem to be effective on most personality types
[
30
]. The NUDGE platform uses the concepts of feedback,
self-monitoring, social role, simulation, tailoring, reminders,
rewards and personalization.
Positive Gaming
The concept of positive computing was defined by Calvo
and Peters (2014) [
9
] and includes three different design
approaches. The preventative design methodology excludes any
negative influence of the systems towards the user, while the
active design methodology tries to integrate elements, that
specifically use positive influence on the user. Finally, the
dedicated design approach focuses on applications that have
wellbeing as their primary goal. To implement those design
strategies [
9
] also suggest different factors such as positive
emotions, motivation, self-awareness, and empathy that can
be utilized when building positive applications. The NUDGE
platform uses the concepts of preventative and active design
using different intra- and interpersonal factors such as social
components and a quantified-self avatar.
PRELIMINARY WORK
The target group of the NUDGE platform are adolescents
aged from 14 to 17 years. In preparation of the nutritional
game design a survey was conducted. The aim was to
describe needs, wishes and motives of German adolescents
regarding nutritional and digital games, in order to design a
target group-specific serious game fostering an improved
nutrition. Literature [
13
][
15
] indicates that nutrition information
in adolescents is deficient and needs to be promoted. In 2010,
the nutrition report of the German Nutrition Society (DGE)
revealed that only about 50% of adolescents are adequately
informed about nutrition [
13
]. The questionnaire was developed
through an interdisciplinary team of nutritionists and computer
scientists. Socio-demographic and anthropometric data were
obtained as well. The 43-item questionnaire has been carried
out in the form of hard-copy and could be completed in 15
to 20 minutes. In total, 339 adolescents aged from 13 to 18
years (46% female), participated in the survey, which has been
conducted in six general secondary schools of the city and
administrative district of Rosenheim between June 2016 and
June 2017. The survey revealed that the nutritional knowledge
in German adolescents is deficient. At same time, most
adolescents play digital games and desire nutrition information
in digital games. Results are in line with findings of another
survey (2016) [
15
]. According to this survey two third of
the 12 to 19 years old participants play digital games daily
or several times a week. Taken together, a serious nutritional
game seems to be a potential educative and preventive tool to
impart nutritional knowledge in order to promote a healthy
lifestyle in adolescents.
SYSTEM DESIGN
The NUDGE platform is built as a system connecting multiple
intervention bricks. The core of the platform is a digital avatar.
It represents the health state of the user based on a digital
nutrition diary. The body composition of the avatar reflects
weight gain and loss. In addition to the physically adaption, the
avatar also expresses moods such as hungry, lonely or excited.
These moods should motivate the user to perform specific
platform actions such as filling his nutrition diary, interacting
with groups, or playing serious games. The avatar can enter
different serious mini-games such as the game prototype "Fit,
Food, Fun", which focuses on macro-nutrients and energy
content of food. Other platform games address physical activity
or micro-nutrient effects. Additionally, the user is motivated
by a social network and real life challenges, such as group
cooking events. He receives nudges about progress events and
social comparisons. The following components try to include
the before mentioned persuasive or positive strategies.
Avatar as Central Platform Element
Within the avatar different persuasion concepts are combined.
First, the avatar can be adapted to the user’s appearance using
different hair, clothing and color schemes. The designs were
specifically chosen to create an emotional connection. This
design should increase the caretaking motivation between the
users and the avatar using a schema of childlike characteristics
[
17
]. At the same time the avatar visualizes the nutrition status
of the user based on a dietary record. If the user eats healthy
for more than three days, the avatars bodyweight will decrease
and new clothing designs will be available. To prevent weight
gain from causing negative psychological effects, the body
sizes are limited to 5 stages and were carefully selected in a
way that positively depicts even the heavier avatar versions.
Besides this visual feedback, the user can also experiment
with nutritional effects using a fast forward scenario. This
scenario shows the nutrient contents and their implications,
in the given future dietary situation [
25
]. Both approaches
utilize the self-quantification and simulation strategies of the
persuasive system design. Regarding positive computing the
avatar should externalize the user’s emotions concerning his
healthy/unhealthy behavior and thus ease negative feedback
given by the system, while still giving motivation through
positive feedback. Finally, the avatar serves as a bus between
the different serious games. For example, the avatar spends
energy by playing the serious mini-games to limit the screen
time for the participating adolescents. While the user’s
nutrition based on the dietary record affects the avatars’ body
composition, the user’s real life physical activity measured by
Google Fit API impacts the avatar’s energy level [
24
]. This
physical activity is used to increase the avatar’s energy and
thus represents another real-life connection. Further avatar
characteristics, such as the current nutrient level will be
integrated in future serious games e.g. by decreasing visibility or
slowing movement. Besides the simulation state of the avatar
regarding real life values such as nutrition and activity, the
avatar also shows the platform status. For example, the avatar
will show hunger, if the user has not updated the diary, and
it will be excited, if the user has not played any games in a
certain time frame. This status feedback serves as a nudge
based on the user’s motivation through self-competition [
10
].
Social and Motivational Elements
Since the NUDGE platform tries to encompass real-life
behavior change, the virtual avatar and serious games components
might not be sufficient to guide the users in their transition.
Additional persuasive and positive elements that were
incorporated are personality dependent nudges, social support groups
and real-life challenges.
According to [
29
] 6 of the 21 reviewed persuasive games for
nutrition include a social support strategy. In the NUDGE
platform, social support is given by groups of 5-10 people, that
share challenges, a leaderboard and access to social games,
such as the ISS space game. In case of missing social contacts
with similar problems, the system will recommend groups
based on age, location, gender and BMI. The group system
including the group size, group management and leaderboard
was evaluated in a small focus group with five participants and
a usability test with five further participants was conducted
as well [
23
]. Both evaluation methods revealed a positive
feedback on the general approaches, while the game design
and usability were still criticized.
It has been shown that tailoring nudges and personalizing
achievements can strongly increase the motivational effect
[
28
]. Our personality dependent nudges are based on seven
gamer types identified by the BrainHex model [
26
] and the Big
Five personality types [
18
]. Those types are used to select the
type of nudges users receive. For example, someone who is a
seeker in the BrainHex model, would receive praise nudges on
diary entries, physical activity or weight loss. In addition to
event nudges, there are achievement nudges such as playing
all games, or regularly filling the dietary diary.
The real-life group challenges are integrated in the form of
social cooking events. This kind of challenge solves multiple
issues of real-life challenges. First, it validates the user’s action
by the social feedback. Secondly, it offers social motivation
for the user to win the challenge. Finally, it opens a platform
for exchange about the received nutritional knowledge and
other platform elements. These real-life group events were
evaluated in a small user study [
23
] with nine participants,
that conducted six different group cooking events within two
weeks. The study showed, that young people are interested
in such events. The most effective motivational elements are
the leaderboard list, showing the best cooking event/host of
each group, the motto (e.g. Blue Titanic Dinner), giving each
cooking event a creative aspect, and the ingredient challenges,
telling the host to e.g. involve salmon in his dinner.
"Fit, Food, Fun" as a Serious Game
The NUDGE platform combines different serious games such
as an ISS space game or a role-play exergame. This chapter
exemplary describes one of the serious game prototypes called
"Fit, Food, Fun" [
37
]. This game concentrates on improving
the nutritional knowledge and on strengthening skills in using
that knowledge to change dietary behavior. The knowledge
transfer is embedded in a journey through Europe. In every
country the user has to succeed in three minigames:
The Card Game offers the player two different cards with a
sort of food each. The challenge is to find the card with the
highest or lowest value in a certain category like carbs, fats,
proteins and calories.
In the Estimation Game the user has to guess the amount of
sugar or fat (displayed as cubes of sugar and drops of fat) that
is contained in a specific type of food.
In the Backpack Game the player must fill a backpack with
food which should supply enough energy for a certain activity
like swimming or running. Without enough energy, the player
won’t make it to the finish line. Choosing too much energy
slows down the player resulting in a lower score.
The first two games impart knowledge about the nutrients
of food whereas in the third game the user learns about the
equivalence between physical activity and these nutrients.
In addition to the link of nutritional knowledge and gaming
strategies, this serious game also integrates different
educational concepts [
6
]. For example, the transition between
countries as well as the transition within the mini-games of
one country were designed along the AVIVA [
31
] model for
teaching. Additionally, the game elements have been checked
against the ARCS model [
21
] and redefined to cover at least
one of the four motivational design elements. For example,
the different country levels were restructured into a travel
route through Europe and complemented with information
about each region to increase the curiosity of players.
CONCLUSION AND FUTURE WORK
The NUDGE platform is research project in progress. It tries
to encompass a holistic set of persuasive and positive
measures into a serious game platform for health. While the major
design and implementation steps are concluded, each
component still needs to be improved through small focus group
interviews. Also, the results of the preliminary survey will be
included until the final evaluation. The final NUDGE platform
is going to be evaluated in a pilot study in spring 2018.
Different outcomes like nutrition knowledge and motivation will
be assessed using appropriate questionnaires. To compare the
characteristics of participants, the Big Five types [
18
] and the
BrainHex gamer types [
26
] will be derived. Additionally,
phenotypic data (gender, age, body weight, body height, hip and
waist circumferences) will be obtained. The study outcome
will be assessed with different validated questionnaires such
as the User Experience Questionnaire [
22
] and the System
Usability Scale [
7
]. Additionally, a domain specific survey will
be used to evaluate the knowledge and skill gain in nutrition.
Finally, motivational questionnaires will be used pre and post
study to show any changes in the users attitude. We expected
the pilot study to show how knowledge gain and behavior
change can be increased through persuasive and positive game
elements. Furthermore, we want to show that the users feel
safe and motivated during their behavioral transition due to
the social and motivational platform framework.
ACKNOWLEDGEMENTS
The preparation of this paper was supported by the enable
cluster and is catalogued by the enable steering committee as
enable 008 (http://enable-cluster.de). This work was funded
by a grant of the German Ministry for Education and Research
(BMBF) FK 01EA1409H.