Less Frictional Skin Feels Softer in a Tribologically Paradoxical Manner
In general, the friction coefficient of a soft object, which has a low elastic modulus, is greater than that of a hard object. Briefly, friction and hardness are physically correlated. Given this relationship, a question naturally arises: are they perceptually coupled? We hypothesized that the highe...
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| Format: | Article |
| Language: | English |
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IEEE
2022-01-01
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| Series: | IEEE Access |
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| Online Access: | https://ieeexplore.ieee.org/document/9775937/ |
| _version_ | 1817987841796341760 |
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| author | Naomi Arakawa Naoki Saito Shogo Okamoto |
| author_facet | Naomi Arakawa Naoki Saito Shogo Okamoto |
| author_sort | Naomi Arakawa |
| collection | DOAJ |
| description | In general, the friction coefficient of a soft object, which has a low elastic modulus, is greater than that of a hard object. Briefly, friction and hardness are physically correlated. Given this relationship, a question naturally arises: are they perceptually coupled? We hypothesized that the higher an object’s surface friction coefficient, the softer it would feel in a physically consistent manner. To confirm this hypothesis, we conducted two types of psychophysical experiments using skin-like materials made of polyurethane and human cheeks as stimuli considering the potential applications in cosmetics. In experiment 1, skin-like objects with the same dimensions and stiffness were coated with powders so that they had different friction coefficients. Participants actively explored and evaluated the softness of these surfaces using their fingers. Their exploratory motions were restricted to either pressing or rubbing. When participants repeatedly pressed the surfaces with no sliding motion, they judged the softness of all the surfaces to be equal. In contrast, when participants rubbed the surfaces, they judged the surfaces with lower friction (i.e., more slippery) as softer than the surfaces with higher friction. In experiment 2, the same results were obtained using human cheeks, one side of which was lubricated to be more frictional. This psychophysical interference between hardness and friction is paradoxical in terms of tribology and contact mechanics. We discuss the potential reasons that led to these results. |
| first_indexed | 2024-04-14T00:27:17Z |
| format | Article |
| id | doaj.art-3d178ebf71554ce6abdcbaa4c5d8d038 |
| institution | Directory Open Access Journal |
| issn | 2169-3536 |
| language | English |
| last_indexed | 2024-04-14T00:27:17Z |
| publishDate | 2022-01-01 |
| publisher | IEEE |
| record_format | Article |
| series | IEEE Access |
| spelling | doaj.art-3d178ebf71554ce6abdcbaa4c5d8d0382022-12-22T02:22:41ZengIEEEIEEE Access2169-35362022-01-0110552795528710.1109/ACCESS.2022.31758759775937Less Frictional Skin Feels Softer in a Tribologically Paradoxical MannerNaomi Arakawa0https://orcid.org/0000-0003-0536-1262Naoki Saito1https://orcid.org/0000-0003-3996-2410Shogo Okamoto2https://orcid.org/0000-0003-2116-7734MIRAI Technology Institute, Shiseido Company Ltd., Takashima, Yokohama, JapanMIRAI Technology Institute, Shiseido Company Ltd., Takashima, Yokohama, JapanDepartment of Computer Sciences, Tokyo Metropolitan University, Hino, Tokyo, JapanIn general, the friction coefficient of a soft object, which has a low elastic modulus, is greater than that of a hard object. Briefly, friction and hardness are physically correlated. Given this relationship, a question naturally arises: are they perceptually coupled? We hypothesized that the higher an object’s surface friction coefficient, the softer it would feel in a physically consistent manner. To confirm this hypothesis, we conducted two types of psychophysical experiments using skin-like materials made of polyurethane and human cheeks as stimuli considering the potential applications in cosmetics. In experiment 1, skin-like objects with the same dimensions and stiffness were coated with powders so that they had different friction coefficients. Participants actively explored and evaluated the softness of these surfaces using their fingers. Their exploratory motions were restricted to either pressing or rubbing. When participants repeatedly pressed the surfaces with no sliding motion, they judged the softness of all the surfaces to be equal. In contrast, when participants rubbed the surfaces, they judged the surfaces with lower friction (i.e., more slippery) as softer than the surfaces with higher friction. In experiment 2, the same results were obtained using human cheeks, one side of which was lubricated to be more frictional. This psychophysical interference between hardness and friction is paradoxical in terms of tribology and contact mechanics. We discuss the potential reasons that led to these results.https://ieeexplore.ieee.org/document/9775937/Cheekfrictionhardnesslubricationpolyurethanesoftness perception |
| spellingShingle | Naomi Arakawa Naoki Saito Shogo Okamoto Less Frictional Skin Feels Softer in a Tribologically Paradoxical Manner IEEE Access Cheek friction hardness lubrication polyurethane softness perception |
| title | Less Frictional Skin Feels Softer in a Tribologically Paradoxical Manner |
| title_full | Less Frictional Skin Feels Softer in a Tribologically Paradoxical Manner |
| title_fullStr | Less Frictional Skin Feels Softer in a Tribologically Paradoxical Manner |
| title_full_unstemmed | Less Frictional Skin Feels Softer in a Tribologically Paradoxical Manner |
| title_short | Less Frictional Skin Feels Softer in a Tribologically Paradoxical Manner |
| title_sort | less frictional skin feels softer in a tribologically paradoxical manner |
| topic | Cheek friction hardness lubrication polyurethane softness perception |
| url | https://ieeexplore.ieee.org/document/9775937/ |
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