Psychophysics of footwear fit and a methodology for needs elicitation
by Au Yim Lee
Ph.D. Industrial Engineering and Logistics Management
xxi, 174 leaves : ill. (some col.) ; 30 cm
Footwear comfort is a complicated entity. Therefore, identifying related needs is the first step towards developing comfortable footwear. Fit and aesthetic designs have been considered to be the most important criteria when buying footwear. The focus of this thesis is to identify the customer needs for footwear comfort as well as develop methodologies to study the attractive attributes of footwear design and the relationships among the foot-shoe allowances, perceived footwear fit and fit preferences....[ Read more ]
Footwear comfort is a complicated entity. Therefore, identifying related needs is the first step towards developing comfortable footwear. Fit and aesthetic designs have been considered to be the most important criteria when buying footwear. The focus of this thesis is to identify the customer needs for footwear comfort as well as develop methodologies to study the attractive attributes of footwear design and the relationships among the foot-shoe allowances, perceived footwear fit and fit preferences.
The results of one-on-one interviews indicate that footwear comfort and discomfort are found to embed positive and negative sensations respectively, especially in relation to tactile, visual, auditory and olfactory sensations. Important characteristics of comfortable shoes appear to be a good fit, suitable heel height, no localized pressure under the ball of the foot and an attractive appearance. Shoes with a poor fit in the forefoot region tend to be perceived as uncomfortable. Wilcoxon signed rank tests showed significant differences in ten perceived characteristics between comfortable and uncomfortable shoes, including: “like the size”, “uncomfortable shoes”, “unpleasant odors”, “like the texture”, “like the feeling”, “discomfort/pain”, “comfortable shoes”, “right temperature”, “right humidity”, and “like the sound emitted”. The ten items reliably (Cronbach alpha > 0.9) distinguished between comfortable and uncomfortable shoes. There were no significant differences between comfortable and uncomfortable shoes for aesthetic-related characteristics.
Thereafter, a methodology was proposed to investigate the aesthetic requirements of leather shoes. A ratio scale of customer satisfaction (CS scale) and a new index; namely, the Customer Satisfaction Improvement Index (CSII) was developed. Three groups of respondents, “young office ladies”, “mature office ladies” and “teacher or trainer”, were recognised within the 50 respondents and specific needs for attractiveness were identified for each group. As a result, the proposed methodology enhances the benefits of applying Kano’s method, which classifies product attributes into different categories, for investigating the needs in attractiveness of different products in the population with multiple market segments.
The last part of the thesis is focused on determining the relationship between the objective and the subjective measures related to footwear fit. Twenty In-Shoe Shape Simulating Instruments (ISSIs) were developed to assess the shape of the foot inside the shoe. These reusable ISSIs could be economically produced at a cost of around HK$6 each. An experiment conducted with these ISSIs showed that the preferred perceived tightness was induced by 5 of the ISSIs having a thickness of 0.66-1.11mm and made of silicone (Elastosil ® M 4600). In this psychophysical study, two prediction models were proposed to predict the perceived footwear fit by considering the foot-shoe allowances in the toe, metatarsophalangeal joint (MPJ) and mid-foot region. As the participants’ perception of footwear fit and preference were taken into consideration, the third degree polynomial relationship was constructed to predict the preference rating (7-point Likert scale) from the perceived footwear fit (5-point scale). In addition, the ideal and acceptable foot-shoe allowances were determined at foot width and foot girth dimensions. The results of the signal detection analysis indicate that participants felt neutral or liked the perceived footwear tightness (i.e. preference rating ≥ 4) in more than 80% of the cases where foot-shoe allowance was no more than 6.37mm, 12.09mm and 10.72mm at the foot breadth, ball girth and waist girth respectively.
This thesis consists of qualitative and quantitative findings related to the needs of footwear comfort. The invention of ISSI could help the footwear customization industry in determining the preferable foot-shoe allowance for each individual customer. The proposed tolerance for perceived tightness could be useful in designing a shoe last for mass production.