Poster Session II

HAI 2017, October 17–20, 2017, Bielefeld, Germany

Exploring Mediation Effect of Mental Alertness for
Expressive Lights
Preliminary Results of LED Light Animations on Intention to Buy Hedonic Products
and Choose between Healthy and Unhealthy Food
Sichao SongThe Graduate University for Advanced Studies(SOKENDAI)
Department of Informatics
Tokyo, Japansichaos@nii.ac.jp

Seiji Yamada
National Institute of Informatics
Tokyo, Japanseiji@nii.ac.jp

ABSTRACT

Expressive light has been explored in a handful of previous studies as a means for robots, especially appearanceconstrained robots that are not able to employ humanlike expressions, to convey internal states and interact with people.
However, it is still unknown how different light expressions
can affect a person’s perception and behavior. In this poster,
we explore this research question by studying the effects ofdifferent expressive light animations on people’s intention tobuy hedonic products and how they choose between healthy
and unhealthy food. Our preliminary results show that participants assigned to a positive and low arousal light animation
condition had a higher intention of purchasing hedonic products and were inclined to choose unhealthy over healthy food.
Such findings are in line with previous literature in marketing research, suggesting that mental alertness mediates theeffect of external stimuli on a person’s behavioral intentions.
Future work is thus required to evaluate such findings in ahuman-robot interaction context.
ACM Classification Keywords

H.1.2. Models and Principles: Human factors
Author Keywords

Expressive light; perception; hedonic product; healthy andunhealthy food choice; human robot interaction (HRI); humanagent interaction (HAI).

to convey their internal states rather than humanlike expressions such as facial expressions and gestures. Among themany subtle expressions, expressive light has been exploredin a handful of previous studies[10, 1, 4, 9, 7] and as shown tobe promising due to its extensive design space, intuition, andease to employ. However, many significant research questions
remain unexplored. In this poster, we explore how expressive light can affect human perceptions and decision-making.
In particular, we investigate how different expressive lights
can influence people’s intention to buy hedonic products andhow they choose between healthy and unhealthy food. Crowd
sourcing was used as the method for obtaining experimental
data due to its ease in hiring a large number of participants
and dramatically low cost. We report that the participants who
were exposed to a positive and low arousal light animation
liked hedonic products more and were more inclined to buy
them compared with the participants who were exposed toeither a negative and high arousal light animation or no lightanimation. Moreover, a higher proportion of the participants
who were exposed to the positive and low arousal light animation preferred to choose unhealthy food over healthy food. We
are currently working on installing an LED lighting system
to an iRobot Create 2 robot and going to use it as a robotic
platform to further evaluate our findings in human-robot interaction scenarios such as service robot-customer scenario.
EXPERIMENT
Expressive Light Design

INTRODUCTION

It is a trend for robots to act socially, and appearanceconstrained robots are no exception. Due to their constrained
embodiments, there robots have to rely on subtle expressions
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HAI ’17, October 17–20, 2017, Bielefeld, Germany© 2017 ACM. ISBN 978-1-4503-5113-3/17/10. . . $15.00
DOI: https://doi.org/10.1145/3125739.3132598

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In this work, we attached a programmable LED strip (AdafruitNeoPixel LED strip) to the front-bottom of a computer monitor.
We defined two parameterized light animation patterns: squareand sinusoidal. Previous studies[5, 6, 8, 9] suggested a relationship between color and perceived affection. Particularly,
they suggested that red is associated with negative emotions
and green is associated with positive emotions. Accordingly,
we designed two light animations, low intensive triangle waveform in green color and high intensive square waveform in redcolor. The intension (frequency) and waveform are introduced
to amplify the color effects and manipulate the perceptionof light animation in the arousal level. We hypothesize thatthe positive and low arousal (PL) light animation can relax

Poster Session II

HAI 2017, October 17–20, 2017, Bielefeld, Germany

a person and thus decrease his or her mental alertness, while
the negative and high arousal (NH) one can cause a person to
become tense and thus increase his or her mental alertness.
Experiment Design

Two experiments were designed to explore how expressive
lights can affect people’s intention to buy hedonic products
and how they choose between healthy and unhealthy food.
For the hedonic product experiment, 300 Japanese participants (89 female; 221 of them aged between 30 to 49) wererecruited; for the food choice experiment, 300 Japanese participants (90 female; 222 of them aged between 30 to 49) wererecruited. Every participant who completed our study waspaid 5 Japanese yen.
A pre-design session was held to decide the hedonic products
and healthy and unhealthy food. The products that we chosefor the hedonic category were Haagen-Dazs ice cream, AppleWatch, Sony headphones, and Kobe beef, the food productsin the healthy category were baked potato [2], granola bar [2],and salmon salad, and the food in the unhealthy category wasfried potato [2], Snickers[2] and fried pork rice covered withcheese.
Hedonic Products

The independent variable was the LED light animation (positive and low arousal, negative and high arousal, no light animation; between-participant). The dependent variables were theperceived valence, likeness of the product, and the purchaseintention. A seven-point Likert scale was provided for eachdependent variable (ranging from 1, strongly disagree, up to7, strongly agree). Each participant was assigned to one of
the three conditions of LED light animation. Overall, eachcondition involved 100 participants.
Healthy vs. Unhealthy Food

Similar to the hedonic product experiment, the independent
variable was the LED light animation (positive and low arousal,
negative and high arousal, no light animation; betweenparticipant). The dependent variables were the perceived valence and choice of food (either healthy or unhealthy one, outof the two). A seven-point Likert scale was provided for eachdependent variable. Each participant was assigned to one of
the three conditions of LED light animations. Overall, eachcondition involved 100 participants.
Results
Hedonic Products

To investigate the effects of the factor LED light animation, weconducted a one-way analysis of variance (ANOVA) for eachdependent variable. Regarding perceived valence, the ANOVA
yielded significant difference [F(2, 1197) = 6.1406, p < 0.01].
Post-hoc independent-sample t-tests with Holm’s correction
revealed that the participants assigned to the PL condition
perceived the stimuli videos more positively (or pleasurably)
than those who were assigned to the NH condition (M positive =3.54, SD positive = 1.74; Mnegative = 3.13, SDnegative = 1.60; p <0.01). Regarding perceived valence, significant difference
was found [F(2, 1197) = 4.4667, p < 0.05]. Post-hoc test
revealed that the participants assigned to the PL condition

488

liked the products more than those who were assigned to theNH condition (M positive = 3.59, SD positive = 1.75; Mnegative =3.25, SDnegative = 1.77; p < 0.05). Regarding purchase intention, the ANOVA analysis showed significant difference[F(2, 1197) = 5.8041, p < 0.01]. Post-hoc test revealed
that participants assigned to the PL condition had a higher
purchase intention than those who were assigned to theNH condition (M positive = 3.52, SD positive = 1.87; Mnegative =3.11, SDnegative = 1.78; p < 0.05).
Healthy vs. Unhealthy Food

We conducted a one-way ANOVA for the dependent variable perceived valence. To analyze the choice of food between healthy and unhealthy food, we applied Pearson’s
chi-squared test. Regarding perceived valence, the ANOVA
yielded significant difference [F(2, 897) = 19.125, p < 0.001].
Post-hoc independent-sample t-tests with Holm’s correction
revealed that participants assigned to the PL condition perceived the stimuli videos more positively than those who wereassigned to the NH condition (M positive = 3.46, SD positive =1.56; Mnegative = 2.83, SDnegative = 1.65; p < 0.001). In addition, the participants assigned to the no light animation
condition perceived the stimuli videos more positively thanthose who were assigned to the NH condition (Mneutral =3.59, SDneutral = 1.63; Mnegative = 2.83, SDnegative = 1.65; p <0.001). Regarding choice of food, pearson’s chi-squared test
suggested a significant difference (χ 2 (2) = 7.4516, p < 0.05).
Post-hoc independent-sample t-tests with Holm’s correction
showed that a higher proportion of participants assigned tothe PL condition chose unhealthy food over healthy food thanthose who were assigned to the no light animation condition(71.67%vs.61.67%; p < 0.05).
DISCUSSION

Our results show that the participants assigned to the textitpositive and low arousal condition had a higher intention ofpurchasing hedonic products. In addition, a higher proportionof them chose unhealthy over healthy food. Such findings arein line with previous studies in marketing research, suggesting that mental alertness may mediate the effect of external
stimuli on a person’s behavioral intentions. In particular, D.
Biswas et al. found that consumers tend to choose less healthy
food options when ambient lighting is dim (vs. bright)[2].
G. Guido et al. propose that consumers who are exposed tocertain conditions of blue lighting are more inclined to purchase hedonic products rather than utilitarian ones [3]. Both ofthese studies indicate the mediation effect of mental alertness,claiming that a lower level of mental alertness drives people totake risks and reduce their ability of self-control, which in turnwould reduce the likelihood of making rational purchase decisions on hedonic products and choosing healthy options. In
this work, we observed similar behaviors from the participants,
which implies that the positive and low arousal light animation successfully reduced the participants’ mental alertness
and thus caused them to be inclined to buy hedonic products
and choose unhealthy food. This phenomenon was observed
strongest between the positive and low arousal condition andthe negative and high arousal condition.

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HAI 2017, October 17–20, 2017, Bielefeld, Germany

3. Gianluigi Guido, Luigi Piper, M Irene Prete, Antonio
Mileti, and Carla M Trisolini. 2017. Effects of Blue
Lighting in Ambient and Mobile Settings on the Intention
to Buy Hedonic and Utilitarian Products. Psychology &Marketing 34, 2 (2017), 215–226.
4. Chris Harrison, John Horstman, Gary Hsieh, and ScottHudson. 2012. Unlocking the expressivity of point lights.
In Proceedings of the SIGCHI Conference on Human
Factors in Computing Systems. ACM, 1683–1692.
5. Banu Manav. 2007. Color-emotion associations and color
preferences: A case study for residences. Color Research& Application 32, 2 (2007), 144–150.
6. Niels A Nijdam. 2009. Mapping emotion to color. Book
Mapping emotion to color (2009), 2–9.

Figure 1. An iRobot Create 2 robot that equipped with a LED strip
showing red light.

We are now working on installing an LED lighting system toan iRobot Create 2 robot (see Fig. 1) and going to use it asa robotic platform to further evaluate our findings in humanrobot interaction scenarios.
ACKNOWLEDGMENTS

This study was partially supported by JSPS KAKENHI “Cognitive Interaction Design" (No. JP26118005).
REFERENCES

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