Sensibility Evaluation of an Exfoliating Lotion with Supreme Tactile
Impression during Wiping Motions

Takeshi Asai1, Yoichi Yamazaki2, Yusuke Tani2, Kensuke Tobitani2, Hiromi Yamamoto1, Noriko
Nagata2
1. Research and Development Department, Naris Cosmetics Co., LTD., Osaka, Japan
2. Graduate School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan

Correspondence to: Takeshi Asai
E-mail: t_asai@naris.co.jp; Tel: +81-6-6346-6574; Fax: +81-6-6346-6579
This paper is original.

Sensibility Evaluation of an Exfoliating Lotion with Supreme Tactile Impression during
Wiping Motions
Takeshi Asai1, Yoichi Yamazaki2, Yusuke Tani2, Kensuke Tobitani2, Hiromi Yamamoto1, Noriko Nagata2
1. Research and Development Department, Naris Cosmetics Co., LTD., Osaka, Japan.
2. Graduate School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan.

ABSTRACT
We aim to provide cosmetics that appeal to users’ “sensibility” and have accordingly developed cosmetics basedon a sensibility evaluation. We examined exfoliating lotions that can be applied to a cotton pad and gently wiped
across the stratum corneum, i.e., the outermost layer of the skin. Our method correlates the visualized
psychological structure with measured physical quantities.
To visualize the psychological structure when using an exfoliating lotion, we selected appropriate evaluation words
and conducted a one-month usage test. Using factor analysis, we evaluated nine factors that are related to the value
judgments of subjects using the exfoliating lotions. Next, we analyzed the causal relationships between thesefactors via structural equation modeling and modeled the psychological structures of the users. The model fit
indices were satisfactory (GFI = 0.952; RMSEA = 0.000). The subconsciously important perceptions appeared tobe “frictional feeling” and “wiped-off feeling,” both of which are derived from the tactile impression imposed by
the wiping motion.
Next, we analyzed the relationship between the frictional force and the tactile impression. To evaluate the physicalquantities related to the “frictional feeling” and the “wiped-off feeling,” we examined the frictional force of wiping.
For 12 types of exfoliating lotions, we measured the dynamic friction coefficient and the time profile of thefrictional force. The dynamic friction coefficient was measured using a friction tester while mechanically wiping
the artificial skin. The time profile was measured using an in-house designed dedicated device while subjects
wiped the lotions from the artificial skin. The factor scores calculated from the subjective evaluation were thencorrelated with the dynamic friction coefficients. The “frictional feeling” and “wiped-off feeling” showed inverse
correlations with the dynamic friction coefficient, and we found that they could not be evaluated as independent
elements (with correlation coefficients of r = −0.820 and 0.744, respectively). Therefore, to identify physicalquantities that can independently affect the two factors, we extracted the eight-dimensional vibrational feature
quantities in the time–frequency domain from the time profile and correlated them with the factor scores in a
multiple regression analysis. The factor scores of the “frictional feeling” and the “wiped-off feeling” were
estimated with high accuracy (r2 = 0.672 and 0.722, respectively). Each factor corresponded to a different
vibrational feature, confirming that the factors are physically independent. This result suggests that both factors
can be simultaneously increased by controlling the frictional force. Based on this result, we attempted to develop
an exfoliating lotion that enhances the vibration features and consequently intensifies the two examined factors.

INTRODUCTION
Recently, the term “KANSEI value” has been recognized as a keyword in Japanese manufacturing industries.
KANSEI is a Japanese term resembling the English word “sensibility”. The Ministry of Economy, Trade andIndustry of Japan defined the “KANSEI value” as a value that materializes when a product appeals to a person’s
aesthetic sense and arouses their emotions and empathy. Examples in which the “KANSEI value” was applied asa manufacturing measure have been reported1)-3).
To develop cosmetic products with high KANSEI value, it is necessary to visualize the psychological structurethat extends to the subconsciousness concerning sensibility. For example, Shimoda et al. researched the comfort
of lotions. They analyzed the sensory evaluation results for various types of skin lotions and examined the structureof the impression that a user feels4). However, the current study was limited to grasping the impression of a single
use and did not formulate the causal relationship between the multiple impressions that lead to value judgments ofcosmetics, including impressions with continued use. However, predicting subjective evaluations via physicalmeasurements is important for developing cosmetics with a high KANSEI value. For example, Ishikubo et al.
examined the relationship between the friction behavior and the penetrative feeling when applying cosmetics usinga friction tester 5). However, the current study was limited to analyzing only a single sensory evaluation item against
a physical measurement and did not analyze the relationship with the complicated impressions that a user feels
when actually using cosmetics.
In this study, we examine the causal relationships between multiple impressions that lead to value judgments ofcosmetics and predict impressions that show large contributions via physical measurements. As the researchsubject, we chose exfoliating lotions, which have the function of removing the unnecessary outermost layers ofskin when applied to cotton pads and gently wiped against the stratum corneum6). Then, we formulated a design
based on sensibility using the relationship between the physical quantities of the frictional force and the impression
evaluation during the wiping motion.

Experiment 1: Visualization of the psychological structure
MATERIALS AND METHODSIn preparation for the usage test, we selected appropriate evaluation words. First, we chose evaluation areas or“scenes” for the users evaluating the exfoliating lotions, i.e., S1) the texture of the exfoliating lotion, S2) the textureof the next skincare item, S3) skin changes with repeated use, and S4) the KANSEI value. Impression words andvalue words for each scene were collected via a free description questionnaire of 17 normal healthy women (23–57-year old) who regularly use exfoliating lotions in their daily regimes. Using statistical methods, we selected a
total of 53 representative evaluation words.
Next, we conducted a one-month usage test with 43 healthy women (30–49-year old), from whom we obtained
informed consent. We divided the study participants into four groups and assigned different exfoliating lotions toeach group. The study participants were required to assign one of the seven grades to each evaluation word.
RESULTS AND DISCUSSION
We analyzed the factor structure of each scene by conducting a factor analysis on the evaluation results. Under thecondition that the eigenvalue is 1.0 or greater, three factors, two factors, one factor, and three factors were extracted
for S1, S2, S3, and S4, respectively. We named the factors interpreted from the factor structure. From this result,nine factors were assumed in relation to the value judgments of the subjects using the exfoliating lotion. Table−1
summarizes the factor structure.
Next, we analyzed the structural equations modeled with the factor scores of each factor as observed variables andmodeled the psychological structure of the users (Figure−1). The model fit indices were satisfactory (GFI = 0.952;
RMSEA = 0.000). For example, we found that the “frictional feeling” has a direct influence on “skin comfort” and“desire to continue exfoliation” in S4 as well as an indirect influence on all three factors of S4 via “moisturizing
sensation” and “smooth sensation”. From Figure−1, the subconsciously important perceptions appear to be“frictional feeling” and “wiped-off feeling,” both of which are derived from the tactile impression imposed by thewiping motion.
In Experiment 2, to examine the physical quantities related to the “frictional feeling” and the “wiped-off feeling,”
we examined the frictional force of the wiping motion. In particular, we measured the dynamic friction coefficientand the vibrational features that contribute to the formation of the tactile sensation.

Table−1. Factor structure of each evaluation scene.
S1)

S3)

S2)

S4)

.40
e7

S4）

skin comfort
.73

e8

e9

desire to continue
exfoliation .55

actual feelingof effect
.59

.41
.40

.43
.39

.32

e6

.22

.33

.30

S3）

change in skin
.53
.41

.46

moisturizing
sensation .77

S2）

smoothsensation

.77

.18

.44

.66

e4

e5
.60

S1）

frictional
feelingskin feelingafter applicatione1

wiped-offfeeling

e2
.52

e3
.41

.59

χ2 =10.457,
p=0.916,
GFI=0.952,
AGFI=0.880,
AIC=64.457,
RMSEA=0.000.

Figure−1. Psychological structure of using an exfoliating lotion.

Experiment 2: Determining the relationship between the frictional force and the tactile impression
MATERIALS AND METHODS
Impression evaluation of the texture
We conducted an impression evaluation of the textures of the exfoliating lotions with the informed consent of 30
healthy women (24–56-year old) who did not participate in Experiment 1. The study participants used 12 types of
exfoliating lotions with different textures twice a day and were required to assign grades of 1–7 to 18 evaluation
words of S1, as in Experiment 1.
Measurement of the dynamic friction coefficient
The dynamic friction coefficients of the exfoliating lotions were measured using TYPE-14 (Shinto Scientific Co.,
Ltd.), a friction tester. Cotton pads were set in a holder simulating the curvature of a finger, and 1.5 ml of the
exfoliating lotion was applied. This holder was set on an arm, and a vertical load of 100 gram force (gf) wasapplied. An artificial skin that reproduced a skin texture pattern created with the aid of a 3D printer was set on amoving table. The outward measurement was performed 10 times at a moving distance of 50 mm and a moving
speed of 50 mm/s, and the average dynamic friction coefficients of the 12 types of exfoliating lotions were
measured.
Measurement of the time profile of the friction force
The tactile texture obtained when stroking the surface of an object is formed by acquiring a time profile of theinteraction force occurring between the skin and the object surface via tactile receptors. To measure the time profileof this interaction force, we fabricated a dedicated device shown in Figure−27). This device can measure theinteraction force generated on the surface when wiping the artificial skin with cotton pads. Herein, we analyzed
the frictional force, which is the interaction force in the direction horizontal to the artificial skin surface.
We selected 10 study participants (24–47-year old) from thehorizontal
verticalsubjects in the impression evaluation experiment. Using
cotton pads with 1.5 ml of the exfoliating lotion, the study
participants used their dominant hands to wipe the artificial
skin toward the front 10 times at a speed of approximately
50 mm/s with a pushing force of approximately 100 gf. The
time profiles of the frictional forces of the 12 types of
exfoliating lotions were then measured.

artificial skinload cellhorizontal
vibration plate
verticalvibration plate

Figure−2. Schematic of the device used for
performing measurements.

RESULTS AND DISCUSSION
Impression evaluation of the texture
A factor analysis was performed on the evaluation results under conditions same as those considered in Experiment
1. As a result, three factors having a structure that was nearly same as that in Experiment 1 were extracted. To
compare the similarity between these factors and those considered in Experiment 1, Tucker’s congruence
coefficient was calculated. The factors “frictional feeling,” “wiped-off feeling,” and “skin feeling after application”
had coefficients of 0.889, 0.861, and 0.879, respectively, and were found to be similar. Therefore, it was decided
that the “frictional feeling” and the “wiped-off feeling” obtained in this experiment could follow the structural
equation modeling of Experiment 1.
Relationship with the dynamic friction coefficient
A correlation analysis was
performed
measuredonthe(a) frictional feeling(b) wiped-off feelingdynamic

friction coefficients andthe factor scores of the“frictional feeling” andthe “wiped-off feeling”.
The scatter plots of eachare shown in Figure−3.
The “frictional feeling”
and “wiped-off feeling”

Figure−3. Correlation with the dynamic friction coefficient.

were negatively and positively correlated with the dynamic friction coefficient, respectively (with correlation
coefficients of r = −0.820 and 0.744, respectively). This result confirmed that the “frictional feeling” and “wipedoff feeling” cannot be evaluated as independent elements when only using the dynamic friction coefficient.

Relationship with the vibrational feature quantities calculated from the time profile
The time profile of the frictional force was evaluated via a frequency analysis using the Welch method (window
width: 0.5 s; overlap rate: 0.5) to estimate the power spectral density (hereinafter referred to as power). In this case,considering the sensibility characteristics of the tactile receptors, 0–252 Hz was assumed as the analytical region,
which was discretized in 63 pieces at 4-Hz intervals and examined. This power was calculated for all samples foreach study participant using the average power of the 10 repeat measurements.
Featureextraction

of

the

vibrational components was

1.2

performed

0.8

a

1

principal

factor loadings

via

component analysis of the 120
power

measurements(10subjects × 12 samples). In total,

PCA1
PCA2

0.6

PCA3

0.4

PCA4

0.2

PCA5

0

PCA6

-0.2

eight factors were extracted

PCA7

-0.4
0

50

100
150
frequency (Hz)under the condition that the
eigenvalue was 1.0 or greater;
the cumulative contribution

200

250

PCA8

Figure−4. Basis function of the vibrational properties.

ratio was 76.62%. Figure−4 shows the basis functions of the extracted factors. Consequently, it was confirmed thateach factor represents a different frequency domain. The principal component scores of each factor were calculated
as the vibrational feature quantities.
Next, multiple regression analysis was performed with the factor scores of the “frictional feeling” and “wiped-off
feeling” as the objective variables and thevibrational feature quantities as the explanatory

Table−2. Results of the multiple regression analysis.

variables. The results are summarized inTable−2. The “frictional feeling” and “wiped-

explanatory
variable

main frequency
regionPCA1standardised partial
regression coefficient
frictional
feeling

wiped-offfeeling

0 - 104 Hz-0.569

0.421

PCA2

132 - 160 Hz

―

PCA3

184 - 220 Hz

0.631

feeling” and an opposite positive tendency

PCA4

220 - 252 Hz

―

0.621

(0.421) for the “wiped-off feeling.” This is

PCA5

160 - 184 Hz

0.530

―

similar to the correlation with the dynamic

PCA6

104 - 120 Hz――

friction coefficient. This result shows the

PCA7

96 - 100 Hz――

validity of the vibrational feature quantities

PCA8

60 - 64 Hz――

calculated in this experiment; it also shows thatcoefficient of determination

0.672

0.722

PCA1, having the low-frequency region of 0–

adjusted coefficient ofdetermination

0.549

0.661

p value

0.024

0.003

off feeling” were estimated with high accuracy(r2 = 0.672 and 0.722, respectively) using thevibrational feature quantities. On comparing
these two factors, PCA 1 was found to exhibit anegative (−0.569) correlation for the “frictional

104 Hz as its main component, shows a behavior
similar to that of the dynamic friction
coefficient, which is a quantitative physical

*

*

―
*

―
**

**：p < 0.01, *：p < 0.05

quantity. Conversely, in the high-frequency regions, each factor corresponds to a different vibrational feature, e.g.,“frictional feeling” correlated with PCA 3 (184–220 Hz) and PCA 5 (160–184 Hz) and “wiped-off feeling”
correlated with PCA 4 (220–252 Hz). Therefore, each factor is physically independent. This result suggests thatboth factors can be simultaneously increased by controlling the frictional force.
Based on this result, in Experiment 3, we designed an exfoliating lotion that enhances the vibrational features andconsequently intensifies each factor.
Experiment 3: Development of an exfoliating lotion with superior tactile impressions during wiping motions
MATERIALS AND METHODSEach exfoliating lotion was prepared by blending alcaligenes polysaccharides (Formula A), sodium hyaluronate(Formula B), and hydroxypropyl methylcellulose stearoxy ether (Formula C), which are polymer ingredients, toobtain the same viscosities. In addition, a standard lotion was used, i.e., the lotion that showed the best “frictional
feeling” and “wiped-off feeling” in the impression evaluation of Experiment 2. One study participant measured
the time profile using a method same as that used in Experiment 2.
RESULTS AND DISCUSSION
The power was estimated from the time profile using a same as that used in Experiment 2. Next, the deviation was
calculated based on the power of the standard lotion. With respect to this deviation, based on the analytical resultsof Experiment 2, the integrated value of the power was calculated for the frequency regions corresponding to the“frictional feeling” at 160–220 Hz and the “wiped-off feeling” at 220–252 Hz.
In Figure−5, the integrated values of the power for each factor are taken as the two axes and a scatter diagram isplotted for each sample. It was found that Formula A

wiped-off feeling→15

is superior in both its “frictional feeling” and its“wiped-off feeling” to the conventional exfoliating

10

lotion [origin (0, 0)] used as the standard lotion.

Formula A
Formula B
Formula C

5

Conventional polymer ingredients, such as sodium
hyaluronate and hydroxypropyl methylcellulose

frictional feeling→

0
-5

0

5

10

15

stearoxy ether, improve the “frictional feeling” butdegrade the “wiped-off feeling”. Conversely, aunique thickening behavior has been reported for

-5

-10

alcaligenes polysaccharides8). It is thought that thiscontributed toward improving the "wiping feeling"
without impairing the “frictional feeling”.

-15

Figure−5. Evaluation results for each sample using a
predictive index of the tactile impression.

CONCLUSIONS
By visualizing the “sensibility,” we were able to understand the factors that users subconsciously regard asimportant and predict them by correlating them with physical quantities. First, as a consequence of modeling thepsychological structure of a user, it was suggested that the two factors derived from the texture of an exfoliatinglotion, particularly the tactile impression during the wiping motions, were potentially important. Next, we
examined the relationship of the frictional force during the wiping motion with respect to the tactile impression.
Using the dynamic friction coefficient, the two factors could not be individually evaluated; however, we foundthat they could be independently predicted using vibrational feature quantities calculated from the friction force.
Using this as a predictive index of the tactile impression, it was possible to design an exfoliating lotion that had asuperior texture at the time of wiping; this could not be achieved in the past.
This method will be extremely useful for developing exfoliating lotions and other cosmetics that appeal to users’
sensibility.

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