Human Roughness Perception and Possible Factors Effecting Roughness Sensation

Surface texture sensation is significant for business success, in particular for solid surfaces for most of the materials; including foods, furniture or fabrics. Applications of roughness perception are still unknown, especially under different conditions such as lubricants with varying viscosities, different temperatures, or under different force loads during the observation of the surface. This work aims to determine the effect of those unknown factors, with applied sensory tests on 62 healthy participants. Roughness sensation of fingertip was tested under different lubricants including water and diluted syrup solutions at room temperature (25oC) and body temperature (37oC) by using simple pairwise comparison in order to observe the just noticeable difference threshold and perception levels. Additionally in this research applied force load during roughness observation was tested with pair-wise ranking method to illustrate its possible effect on the human sensation. Obtained results showed that human roughness discrimination capability reduces with an increasing viscosity of the lubricant, where the temperature was not found to be significant. Moreover, the increase in the applied force load showed an increase in the sensitivity of roughness discrimination capability. Observed effects of the applied factors were also used for estimating the oral sensation of texture during eating. These findings are significant for our fundamental understanding to the texture perception, but also could find applications in the material sciences which may include food sciences that needs information about texture perception for the development of new foods with controlled textural features.