Perceptual Characteristics Of Fabric Softness Evaluation Based On Visual-Tactile Modality

When people evaluate material properties of fabrics, softness, which reflects the mechanical properties such as surface, compression, bending and tensile property, is one of the most important tactile sensory. It is affected by vision or audition. It is known that there are differences between the evaluation results under visual and tactile modality. But it is still unclear that the contribution and perceptual characteristics of vision and touch. In the other hand, different touching manners get different mechanical stimuli, which affect the sensitivity of sense. In the research of objective assessment, it is already known softness is significantly related to bending and tensile properties from the correlation coefficient and regression equations between mechanical, physical properties and the results of sensory evaluation. In addition, fabrics have complicated geometric dimensions. Therefore, the perceptual characteristics and the contribution of visual and tactile modality of rubber softness evaluation are unreasonable to represent the fabrics'In order to reveal the psychophysical characteristics of fabrics softness evaluation and the contribution of visual and tactile modality, the research and the conclusion are as follows:1. According to the modalities, touching and observation manners, the psychophysical experiments include 8 perception methods. In comparison with the softness magnitude of the reference sample, the correct proportion of softness evaluation for each manner and each modality was analyzed with respect to the most correlated physical property. The proportion and the most relevant property were fit to a logistic psychometric function. By the fitted psychometric function, the discrimination threshold for each manner and each modality was calculated. With a comparison of all discrimination thresholds, the results showed that the psychometric curve for sensory evaluation on fabric softness was logistic. The discrimination threshold of holding bend is lower than laying press manner's and the visual-tactile modality's is lower than the tactile modality's. Under the visual modality, the discrimination threshold is close to holding bend manner's, moving modality's is lower than static modality's and direct observation's is lower than the picture and video.2. Then discuss the contribution of the different perceptual information to the softness evaluation with the sensory evaluation experiments and perceptual characteristics based on a statistically optimal fashion named "Maximum Likelihood Estimate". The results show that by any touching manner, touching is more strongly weighted than vision. Especially the holding bend manner, the weight of touch is more than 0.9. But for the laying press manner, the weights of two manners are nearly the same. In the other hand, under tactile and visual-tactile modality, the bending and tensile ability are more strongly weighted than compression and surface property. And with vision, the weight of compression and surface property is increased to nearly 0.25.In summary, the most sensitive method of fabric softness evaluation is holding bend under visual-tactile modality. Its discrimination threshold is lower than visual modality. In addition, touching is more strongly weighted than vision, while the bending and tensile ability is more strongly weighted than compression and surface property. The results are consistent with the previous softness evaluation research. It implies that the MLE fashion is applicable for the research for fabrics' perceptual characteristics and the weight of different modalities, touch manner, mechanical and physical properties in sensory evaluation.