Semantically Layered Structure ofTactile Textures
Hikaru Nagano, Shogo Okamoto, and Yoji Yamada
Department of Mechanical Science and Engineering, Graduate School of Engineering,
Nagoya University, Japan ⋆Abstract. This study constructed a multi-layered semantic structure of
adjective pairs that are used to express the tactile properties of materials. We analyzed the causalities between adjectives using the DEMATEL
method, involving twenty-nine adjective pairs and forty-six materials,
and thus constructed a multi-layered structure. The constructed structure contained psychophysical, aﬀective, and preferential layers. The psychophysical layer consisted of words related to the physical properties ofmaterials, which were rough/smooth, uneven/ﬂat, hard/soft, cold/warm,sticky/slippery, and wet/dry. The aﬀective layer included aﬀective sensations such as comfortable/uncomfortable and friendly/unfriendly. The
words related to individual preferences, which include rich/poor, good/bad,like/dislike, and happy/sad, were located on the highest layer of thestructure. The constructed structure helps us understand aﬀective andpreferential perceptions of materials through psychophysical perceptions.
Keywords: Psychophysical perception, Aﬀective perception, Preferential perception, Multi layer, Texture

1Introduction

Tactile textures are expressed using a multi-layered and dimensional perceptualspace. For example, the psychophysical perception of materials, such as roughness, softness, and warmness, and the aﬀective perception of materials, suchas comfortableness and richness, constitute tactile textures. Understanding thestructure of tactile textures is helpful in various ﬁelds such as in the design oftactile texture displays [1, 2] and commercial products with textural aﬃnity [3].
To express the tactile textures of materials, adjective pairs such as “roughsmooth” were commonly used in early studies [4–6]. These studies analyzed
the structures of tactile textures by using adjective pairs. Okamoto et al. [7]analyzed studies on the dimensional structures of tactile textures in order to ﬁnd
a common understanding of such structures. They suggested that psychophysicalperceptions of material are composed of the ﬁve dimensions that are “roughsmooth,”“uneven-ﬂat,”“hard-soft,”“warm-cold,” and “sticky-slippery.” Guest et⋆

This work was in part supported by MEXT KAKNEHI (13J02247 and 24700192)
and Shitsukan 25135717.

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H. Nagano et al.
Table 1. List of twenty-nine adjective pairs used in the experiment
Beautiful-ugly
Friendly-unfriendly
Modern-classic
Sticky-slippery
Clean-dirty
General-Speciﬁc
Natural-artiﬁcial
Strange-usual
Clear-vague
Good-bad
Regular-irregular
Uneven-ﬂat
Comfortable-uncomfortable Happy-sad
Rich-poor
Warm-cold
Hard-soft
Rough-smooth
Wet-dry
Concrete-abstract
Dangerous-safe
Interesting-uninteresting Sharp-dull
Delicate-bold
Itchy-not itchy
Signiﬁcant-insigniﬁcantExciting-boring
Like-dislike
Simple-complex

al. [8] identiﬁed the perceptual or semantic dimensions of psychophysical andaﬀective words describing textural experiences.
Although psychophysical perceptions can be easily connected to the physicalproperties of materials–for example, Young’s moduli are pertinent to softness
percepts–it is diﬃcult to predict the relationship between aﬀective perceptions
and the physical properties of materials. Many studies on the design of aﬀective
perceptions such as richness and comfortableness have implicitly deﬁned andused the multi-layered structure of aﬀective and psychophysical perceptions ofmaterials. Meanwhile, thus far, the semantically layered structure of tactile textures has yet to be systematically established. A layered structure of aﬀective
and psychophysical perceptions of textures was once proposed by Chen et al. [9],in which the structure was based on the correlation coeﬃcients between adjective words. However, a systematic approach with a validation was not developed
because the topic was beyond the main scope of their study.
We established a semantically layered structure of tactile textures based on
the causal relationships between aﬀective and psychophysical words. Such astructure will enhance understanding of the perceptual relationships between
the psychophysical and aﬀective percepts of materials.

2

Experiment to construct a semantically layeredstructure

We analyzed the causalities between adjective pairs using the DEMATEL (decision making trial and evaluation laboratory) method [10] that has been mostly
used to analyze, for example, the structure of social problems involving multiple factors. As far as we know, the DEMATEL method has not been used toanalyze the perceptual structures of material surfaces. In the experiments, theparticipants touched materials and evaluated the causalities between adjective
pairs that are potentially related to textural perceptions. The results were integrated across the participants and used to determine a semantic structure oftactile textures. All the experimental procedures, including the recruitment ofparticipants, were approved by the Ethics Committee of the Graduate School ofEngineering at Nagoya University.

Semantically Layered Structure of Tactile Textures

3Table 2. List of forty-six materials

Aluminum foil cloth Fake suede
Iridescent sheet
SpongeArtiﬁcial grass
Fake woven leather Long hair fake fur
Stainless steel scrubber
Magnolia wood
Steel wool
Coarse woven straw Felt
Cork board
Fine Japanese paper Mirror plate
Tile
Corrugated paper Fine woven straw
Mosaic tile
Towel
CottonGlass beads (1.5mm) Oak wood
Urethane resin
Glass beads (3.5mm) Perforated aluminum
Wall paper
Cotton cloth
Crumpled paper
Glass beads (5mm) Pyramid rubber matting Woven linen
DenimGlass beads (7mm) Sapelli wood
Woven rush grass
Fake alligator hide Glossless vinyl sheet Satin
Woven wire mesh
Glossy vinyl sheet
Short hair fake fur
Fake boa
Fake cowhide
Goose feathers
Soft fake fur

2.1

Adjectives representing tactile perception of materials

The twenty-nine adjective pairs shown in Table 1 were used to express tactile
perceptions of materials. These pairs were selected based on the studies on tactile
textures [4–6, 8] and included the ﬁve common adjectives representing the psychophysical percepts of tactile textures [7]. In addition, the list includes aﬀective
words such as “comfortable-uncomfortable” and “rich-poor” that are potentiallyhelpful in the manufacturing of commercial products.
2.2

Method to specify the causalities between adjective pairs

The eleven volunteers (n = 11) actively touched the forty-six types of materials
shown in Table 2 that were singly-presented to each participant in a randomizedorder. The participants were instructed to freely touch them in a box, therefore
they did not see the materials and their touch motions. Then, they evaluatedthe causalities for all permutations of adjective pairs: m P2 = 812, where m isthe number of adjective pairs (m = 29). They scored the causality xij (k) (k =1, 2, . . . , n) in terms of the extent to which a subjective evaluation for materials
using adjective pair i inﬂuenced another one using adjective pair j using a sixpoint scale (5: very inﬂuential, 0: no inﬂuence).

3

Result: Semantically layered network of adjective pairs

3.1

Data analysis: Calculation of total influence matrix

For each participant, the initial direct-relation matrix X (k) ∈ N m×m of thedegrees of causality xij (k) , was normalized to Z (k) as follows:
Z (k) =1s(k)

X (k)

(1)

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H. Nagano et al.
ffeeddFig. 1. Rule of omitting arc while maintaining reachability

where s(k) was the maximal summation of the rows or columns and was determined by
mm∑∑s(k) = max xij (k) ,xij (k)  (i, j = 1, 2, . . . , m).
(2)
i=1

j=1

Next, the average direct-relation matrix A was computed across the participantsas follows:
n1 ∑ (k)aij =zij(3)nk=1(k)where aij and zij
were the elements of A and Z (k) , respectively. Finally, wecomputed the total-relation matrix F as follows:
F = A + A2 + A3 + · · · =∞∑−1

Ab = A(I − A)

.

(4)

b=1

Al is the indirect-relation matrix and indicates the eﬀect from adjective pair ito j after mediating other (l − 1) pairs.
3.2

Construction of multi-layered structure

On the basis of the total-relation matrix F , we determined the multi-layered
structure that expressed the causal relationships between adjective pairs. Thenodes and arcs in the structure represented the adjectives and the presence ofcausal relationships between adjectives, respectively. When the elements fij of F
was larger than a threshold, a directional arc was set from adjective pairs i to j.
In addition, we minimized the number of arcs while maintaining the reachability
between nodes. For example, as shown in Fig. 1, the arc between the two nodes
d and f was omitted when three arcs existed across the three nodes d, e, and f .
We established the two types of structures, as shown in Figs. 2 and 3 using
two threshold levels: 0.050 and 0.035. The structure in Fig. 2 included twenty-one
nodes and forty-eight arcs while twenty-ﬁve nodes and seventy-six arcs existedin Fig. 3. The black nodes were related to none of the other nodes. In otherwords, few participants regarded that they had any causal relationships withthe others. The white nodes were leaf nodes that did not aﬀect the other nodes.
The root nodes that are not inﬂuenced by the others are shown in dark gray.

Semantically Layered Structure of Tactile Textures

Not
influenced
nodeNot
influencing
nodeRich/
PoorNorelation
nodeGood/
BadHappy/
Sad

Beautiful/ Friendly/Interesting/Comfortable/ Strange/ Delicate/
Ugly
Unfriendly Uninteresting Uncomfortable Usual
BoldRough/
SmoothUneven/
Flat

Hard/
Soft

Simple/Complex

Warm/
Cold

Significant/Insignificant
Regular/
Irregular
Dangerous/
Safe
Sharp/Dull

Like/
Dislike

Clear/
Vague

Sticky/Slippery

5Clean/Dirty
Itchy/
Not itchy
Modern/ClassicNatural/
Artificial

Exciting/ Concrete/ General/
Boring Abstract SpecificWet/
DryFig. 2. Example 1: Constructed semantic layered structure (threshold is 0.05)

Not
influenced
node

Not
influencing
nodeNorelation
node

Beautiful/
Ugly

Friendly/Unfriendly

Rich/
Poor

Interesting/
Uninteresting

Good/
Bad

Happy/
Sad

Significant/Insignificant

Exciting/
BoringComfortable/
Uncomfortable

Clear/
Vague

Delicate/
Bold

Sharp/
Dull

Clean/
Dirty
Itchy/
Not itchy
Modern/Classic
Natural/Artificial

Like/
DislikeConcrete/ General/ Dangerous/
Abstract Specific
Safe
Strange/
Usual

Simple/Complex

Regular/
Irregular

Rough/
SmoothUneven/Flat

Hard/
SoftWarm/
Cold

Sticky/SlipperyWet/
DryFig. 3. Example 2: Constructed semantic layered structure (threshold is 0.035)

The lowest layer of the constructed structures contained the six types of adjective pairs: rough/smooth, uneven/ﬂat, hard/soft, cold/warm, sticky/slippery,
and wet/dry. While these pairs are related to the psychophysical perceptions ofmaterials, many of the adjectives in the higher layers expressed aﬀective perceptions. At the highest layer of the structures, the four types of adjective pairs
including rich/poor, like/dislike, happy/sad, and good/bad were located. Thesefour adjective pairs are highly linked to individual preferences. The structures
corresponded to be semantic relationships between adjective words.
In this article, we showed only two examples of structures; however, we alsoestablished other types of structures with diﬀerent threshold values. As well as6H. Nagano et al.

the above two examples, most of the other structures share the same nodes atthe lowest (psychophysical) and highest (preferential) layers. Their diﬀerenceswere observed in the intermediate (aﬀective) layers. Such diﬀerences were also
found in the two sample structures of Figs. 2 and 3. The structure in Fig. 2
included one middle layer, whereas the one in Fig. 3 had two middle layers. In
general, smaller threshold values led to the production of more complex middlelayers.
Although we should carefully validate the constructed structures and theapplication of the DEMATEL method to our purpose, we found some similarities
between the results in this study and those in an earlier study. The constructedstructures included the psychophysical, aﬀective, and preferential words in thelowest, middle, and highest layers, respectively. This arrangement of layers isconsistent with the study of Chen et al. [9], in which the psychophysical percepts
also inﬂuenced aﬀective percepts. In addition, the locations of some aﬀective
words that were commonly used in [9] and in our study are similar. In bothstudies, “exciting” and “rich” (precious and premium in [9]) are placed in thehigher layers whereas “simple” and “delicate” are in the lower layers. Thesesimilarities between [9] and our study apparently support the validity of ourmethod and results.

4Conclusion

We constructed the semantically multi-layered structures of adjectives expressing tactile textures of materials by applying the DEMATEL method that was not
originally designed for the analysis of adjective words. The constructed structures were composed of psychophysical, aﬀective, and preferential layers, andsuch layered structures of adjectives will help in understanding the aﬀective
perspectives of materials.

References
1. Yamauchi, T., Okamoto, S., Konyo, M., Hidaka, Y., Maeno, T., Tadokoro, S.: Realtime remote transmission of multiple tactile properties through master-slave robotsystem. Proceedings of the 2010 IEEE International Conference on Robotics andAutomation (2010) 1753–1760
2. Matsuura, Y., Okamoto, S., Asano, S., Nagano, H., Yamada, Y.: A method foraltering vibrotactile textures based on speciﬁed materials. Proceedings of the 2012
IEEE International Symposium on Robot and Human Interactive Communication(2012) 995–1000
3. Chen, X., Shao, F., Barnes, C., Childs, T., Henson, B.: Exploring relationships
between touch perception and surface physical properties. International Journalof Design 3(2) (2009) 67–76
4. Howorth, W.S., Oliver, P.H.: The application of multiple factor analysis to theassessment of fabric handle. Journal of the Textile Institute Transactions 49(11)(1958) 540–553

Semantically Layered Structure of Tactile Textures

7

5. Yoshida, M.: Dimensions of tactual impressions: I. Japanese Psychological Research 10(3) (1968) 123–137
6. Hollins, M., Faldowski, R., Rao, S., Young, F.: Perceptual dimensions of tactile
surface texture: A multidimensional scaling analysis. Perception & Psychophysics54(6) (1993) 697–705
7. Okamoto, S., Nagano, H., Yamada, Y.: Psychophysical dimensions of tactile perception of textures. IEEE Transactions on Haptics 6(1) (2013) 81–93
8. Guest, S., Dessirier, J.M., Mehrabyan, A., McGlone, F., Essick, G., Gescheider, G.,Fontana, A., Xiong, R., Ackerley, R., Blot, K.: The development and validationof sensory and emotional scales of touch perception. Perception & Psychophysics
73(2) (2011) 531–550
9. Chen, X., Barnes, C.J., Childs, T.H.C., Henson, B., Shao, F.: Materials tactiletesting and characterisation for consumer products aﬀective packaging design.
Materials and Design 30 (2009) 4299–4310
10. Gabus, A., Fontela, E.: Perceptions of the world problematique: Communication
procedure, communicating with those bearing collective responsibility. Battelle
Geneva Research centre (1973)