A Proposal for Subjective Evaluation Method in Small Sample using Visual Analog Scale

Research on impression evaluation such as painting, music, and design is widely implemented in the field of psychology / affective engineering. However, the style of the questionnaire is stepwise in the most case. Numerical values obtained from these questionnaires are treated as interval measures in many cases for convenience but should be handled as an ordinal scale in a strict sense. We propose a Visual Analog Scale (VAS) which marks one point on a straight line as an evaluation value, not a stepwise style. It became possible to perform statistical analysis to comprehend the overall tendency even in a subjective evaluation experiment of a small sample. The feature is to visualize the experimental results by overlaying a box-and-whisker plot and a univariate scatter plot. We conducted an impression evaluation experiment on a representational painting and an abstract painting for the same group of subjects. The number of adjective pairs is 15, and the number of subjects is 30. The box-and-whisker plots can intuitively understand the distribution and trend of the whole. Furthermore, we compare two paintings using hierarchical clustering and could see common clusters. Also, we show box-whisker charts in which the data is pseudo-converted into five stages and clarify the difference between VAS and LS.