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MYU Tokyo
S & M 1182

Impact of the Facial Attractiveness of a Social Reward
on Event-Related Potential Activities and Task Performance
Yasuhiro Ogoshi,* Sakiko Ogoshi,1 Tomohiro Takezawa,2 and Yoshinori Mitsuhashi3
Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
National Institute of Technology, Fukui College, Geshi-cho, Sabae-shi, Fukui 916-8507, Japan
2The National Institute of Vocational Rehabilitation, 3-1-3 Wakaba, Mihama-ku, Chiba 261-0014, Japan
3Faculty of Education and Regional Studies, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan
1(Received October 30, 2015; accepted February 8, 2016)

Keywords: electroencephalography, contingent negative variation potentials, social reward, task
performance

Male participants were presented with pictures of female faces and asked to evaluate thedegree of attractiveness of each image using a questionnaire. Then, the impact of the degree of
attractiveness on subsequent event-related potentials was determined using electroencephalography
conducted while participants completed a word recognition memory task with the facial images
presented as rewards for correct responses. The most attractive faces elicited the largest contingent
negative variation potentials and the greatest improvements in performance.

1.

Introduction

Human learning and cognitive function are considerably affected by environmental andemotional factors. People learn and develop their cognitive capacity through stimuli from theenvironment. People feel joy when learning has been emphasized and attributed to internal andexternal factors. Internal factors depend only on the needs and wants of the learner, whereas
external factors depend on the motivation obtained from external sources. Therefore, to facilitate
learning, it is important for the learner’s environment to be appropriately arranged by others,by matching the learner’s self-esteem with extraneous motivation.(1) Rewards can be effective
motivating tools. It is known that tangible rewards (such as money/valuables and drinks) can
improve the performance of cognitive tasks.(2) Furthermore, social rewards, such as people’ssmiles and attractive faces, particularly of the opposite sex, are also known to enhance cognitive
task performance.(3) Whether people find faces of the opposite sex attractive may depend on
subjective factors inherent to the individual. The manner by which the attractiveness of a faceaffects cognitive functions, such as memory, is an important issue when considering subjective
attractiveness as an indicator of the value of social rewards. By effectively using attractivenessas an index of reward value, its application in individualized learning, for example, using brainmachine interface (BMI) methods, can be predicted.
In this study, we administered a questionnaire before participants performed a memory task.
Participants were asked to rate the face of a person of the opposite sex according to subjective
attractiveness. Next, a memory task was presented on a computer display and participants indicated*Corresponding author: e-mail: y-ogoshi@u-fukui.ac.jp
ISSN 0914-4935 © MYU K.K.

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recognition of previously presented words by pressing a button. If the response was correct, a facial
image of the opposite sex was presented on the display as a reward. This was used to identify thedifferences in the effect of facial images of varying degrees of attractiveness that were provided as
rewards for the memory task. We investigated how different degrees of attractiveness affected theparticipants’ response accuracy in the memory task. We also recorded the event-related potentials(ERPs) of participants while performing the task to examine how contingent negative variations(CNVs) in brain waves associated with attention and anticipation immediately before reward
presentation were affected by expectations of image attractiveness.

2.

Method2.1

Participants
All participants were male university students (N = 7, mean age 22.25 years).

2.2

Experimental conditions(1) Experimental environment
The laboratory used for the electroencephalography (EEG) recordings was a sealed room with
dim illumination. The distance between the display and the participant’s head was approximately
110 cm. The viewing angles of the display were 11.4° for facial image stimuli and 3.6° for Japanesecharacter stimuli.
(2) Stimuli for memorizing and reward
The stimuli for the memory task consisted of 900 words with two Japanese katakana characters
having 30–289 meanings.(4) Also, 15 female facial images were created by synthesizing facial
images of celebrities posted on the Internet, using the facial image synthesizing software(FotoMorph), for presentation as rewards for correct responses in the memory task. Prior to thememory task, participants assessed the female facial images using a questionnaire and rated their
attractiveness. We had each subject complete the questionnaire presented in Fig. 1 for each of 15
photographs of women’s faces prior to the experiment. The first question asked respondents to rate
the attractiveness of the woman in the photograph on a Likert scale with highly attractive being
assigned a value of 10, moderately attractive a value of 0 and unattractive a value of −10. Other
questions on the questionnaire were not used in the selection of the image used in the experiment.
These ratings were used as an indicator of the attractiveness of the faces that were used. We
specifically selected images with high and low attractiveness and used them as social rewards. We
also created a square image painted on a gray background for presentation as a non-reward forincorrect responses. All images were adjusted so that they had approximately the same brightness.
(3) Measures
The following devices were used for EEG recording: (1) polymate AP1532 biological amplifier(TEAC) and (2) Ag/AgCl plate electrodes with an internal diameter of 7 mm (NE-113A, Nihon
Kohden).

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Fig. 1.

(Color online) Questionnaire.

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Sensors and Materials, Vol. 28, No. 4 (2016)(4) Electrode placement for EEG recording
Electrodes were placed in the following sites using 11 channels based on the international 10-20
system. We positioned the ground electrode on the forehead and reference electrodes on the right(A1) and left ears (A2) using referential derivation. Measurement sites included Fp1 and Fp2 (frontalpole), F3 and F4 (frontal), Fz (midline frontal), C3 and C4 (central), Cz (vertex), P3 and P4 (parietal),and Pz (midline parietal). The electrooculogram was also recorded to remove artifacts associatedwith blinking.
(5) Procedure
The experiment was conducted according to the flow diagram shown in Fig. 2. The ninewords to be memorized were displayed. Then, a recognition stimulus word was presented, andthe participants were asked to respond whether or not the word was included in the words to bememorized by pressing a key. After the recognition stimulus was presented, a 1.5-s interval was
included for completing the response. If a participant pressed the key, there was an interval of just
1 s and then the display was switched to a feedback screen of either a female facial image (rated
as highly attractive or moderately attractive) as a reward for a correct response or a gray image(no reward) for an incorrect response. The process from the display of the recognition stimulus toFig. 2.

(Color online) The task flow for one session.

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feedback was considered one trial, which was repeated 36 times to make up one session. In every
session a participant was presented nine new words to memorize.
Of these 36 recognition stimuli, 12 words were those included in the stimuli to be memorized
and the remaining 24 words were new. The 36 trials were divided into two halves, and the correct
response rates for both halves were examined and compared. A total of six trials using highly
attractive female facial images and six trials using moderately attractive female images as rewards
were conducted. The images appeared as rewards randomly.

3.

Analysis

3.1

Analysis of EEG data

EEG data between −1500 ms (pre display of a reward stimulus) and 1000 ms (post display of areward stimulus) were analyzed for the measurement sites listed in § 2.2 (4).
3.2

Analysis of CNV

First, a 10th-order Butterworth band-pass filter (0.5–30 Hz) was applied to the brain wave
data to remove high-frequency noise. Next, we removed trials that included artifacts associatedwith eye movements or blinking from the recorded EEG from the 11 channels by referring to theelectrooculogram data. Only those trials without artifacts were averaged. We set the threshold forthe electrooculogram potential as 100 µV to remove artifacts.
Finally, the baseline value (the average value between −1500 ms before the reward stimulus
display and 1000 ms after the stimulus display) was subtracted from the average waveform
described above to yield the ERP waveform. In this study, the maximum amplitude measured
between −1000 ms before the reward stimulus display and that after the display was regarded as the
CNV value. CNV values were compared between images of different attractiveness.

4.

Results

Figure 3 shows the averaged CNV values of the seven participants. The previous reward
impacts the expectation effect of next reward. The results suggest that the CNV value was higher
for reward images judged as more attractive than for reward images judged as moderately attractive.
As indicated in Fig. 4, the correct response rate was greater when a highly attractive image
was presented than when a moderately attractive image was presented as a reward. The impact of
reward type upon performance became apparent only after a number of sessions. We parsed thedata from the first six and last six sessions of each participant.
In addition to presenting improved accuracy in response to highly attractive rewards overmoderately attractive rewards, participants also presented improved performance when the first setof 6 sessions was compared to the last set of 6 sessions. Furthermore, the correct response rates forthe first and second halves of a single session showed that accuracy was enhanced when a highly
attractive image was used as a reward (see Fig. 4).

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Fig. 3.

5.

Averaged CNV values of seven participants.

Fig. 4. Correct response rates for the first andsecond halves of one session.

Conclusions

The results of this experiment indicated that highly attractive female facial images used as
rewards in a memory task evoked larger CNV values. This suggests that the more attractive thefacial image, the greater the anticipation for the reward. In addition, the accuracy rate for the
memory task improved when an attractive face was presented as the reward stimulus.
Our experiment was conducted with male participants and female images as rewards. Further
experiments with female participants and male rewards would be desirable.
These results should also be confirmed using a larger sample size. In the future, we are planning
to use CNV as a key parameter for developing BMIs to enhance cognitive functions.

Acknowledgements
This work was supported by KAKENHI (Grant-in-Aid for Scientific Research (C) Nos.
21610007 and 24600005, Grant-in-Aid for JSPS Fellows No. 11J40189, and Research Activity
Start-up No. 70581180).

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About the Authors
Yasuhiro Ogoshi is an Associate professor at the Graduate School of Engineering,
University of Fukui in Japan. He received a Ph.D. Degree in Engineering fromthe University of Kanazawa in 2001. He is engaged in studies relating to humaninterfaces.

Sakiko Ogoshi is an Associate Professor at the Department of ElectricalEngineering and Computer Science National Institute of Technology, Fukui College,
in Japan. She received a Ph.D. Degree in Engineering from the University ofKanazawa in 2004. She was a Researcher at the Japan Society for the Promotionof Science and the Faculty of Education and Regional Studies, University of Fukui
from 2011 to 2014. Her research interests include special needs and developmental
disorders and knowledge management systems applied to information technology.
Tomohiro Takezawa was awarded a Ph.D. in Psychology from Hiroshima
University. He specializes in studying cognitive abilities and assistive technology.

Yoshinori Mitsuhashi is a Professor Emeritus and currently a specially-assigned
professor on the Faculty of Education and Regional Studies at Fukui University,
Japan. After graduating from Kwansei-Gakuin University, Department ofExperimental Psychology, in 1972, he finished his graduate studies in 1980. He
became an associate professor at Fukui University in 1981 and left as a professor in
2014. His research covers psychophysiology of cognition and education of handicapped children,
especially studies using electrical acitivity of brain cognitive processes in children and adults withneurodevelopmental disorders.