As factors determining roughness sensation of dot pattern, both spacing and curvature of dot are assumed. In this study, the relationship between these two dimensional parameters and the roughness sensation was investigated. We used a 3D printer to produce various types of samples with different combinations of curvature and spacing, and conducted sensory evaluation to select combinations with the same sense of roughness from among them. As a result of the experiment, as the dot curvature is larger (smaller), the smaller (larger) dot spacing is selected, and a contour map of roughness sensation is created on these two dimensional planes. It was found that roughness sensation is proportional to logarithm of dot curvature, assuming that roughness sensation is proportional to logarithmic value of dot spacing. By this experiment, the magnitude of the influence of dot shape in roughness perception and its individual difference were found.

In order to increase the number of videos playback, we researched on the thumbnail images and the titles which were selected by the viewers. We built the samples and conducted the questionnaires in order to reveal the factors that make a great influence on the evaluation and be clear about the positive levels. We revealed the viewers decide the videos under the influence of the images rather than sentences and words. Also, Images factors are particularly effective for males. On the other hand, females are more affected by sentences and words than males. This research revealed the guidelines that YouTuber creates thumbnail images and titles and the elements to incorporate according to the target the males or the females. As a starting point of this research, we will be able to conduct more detailed research on thumbnail images and titles.