Description:
<jats:title>Abstract</jats:title>
<jats:p>Humans can sense water on a solid substrate without sliding their fingertips. In this study, 20 subjects were presented with small amounts of pure water and aqueous solutions containing various amounts of a thickener. Many subjects distinguished a watch glass containing water from those containing aqueous solutions of the thickener. The most characteristic tactile texture of water reported by participants was a non-slimy feel. Furthermore, friction evaluations and high-speed observations identified frictional resistance as a distinguishing characteristic between water and the thickened aqueous solutions. Notably, no significant fingertip movements were observed when using a high-speed camera, although the frictional coefficients for water (0.18), the 1.00 wt % thickened solution (0.10) and the 5.00 wt % thickened solution (0.05) were significantly different. A regression analysis of the relationship between the tactile evaluation and friction properties suggested that many subjects evaluated the degree of sliminess based on the fluctuation of the frictional coefficient during contact of their fingertips with the watch glasses.</jats:p>