Can pupil size be measured to assess design products?

• We used pupillary variation to assess users' emotion elicited by products.
• We used the scrambled effect allowed participants to adapt to the luminance.
• Negative product images evoked pupillary responses differ from the other emotions.
• Product images viewing skewed to positive emotion in terms of pupillary responses.
• Pupil size measurement tailored to product design assessment.

Some studies assessed aesthetic appreciation by pupillary measurement. While design judgments are also a kind of aesthetic appreciation, design products might be suitable for assessment in pupillary measurement as well. Hence, this study explores the relationship between pupil size and user subjective opinion using forty-eight International Affective Picture System (IAPS) images and forty-eight product images as stimuli. The stimuli are composed of positive, negative, and neutral images. For each trial, participants viewed scrambled versions of image and then viewed unscrambled versions (target image). The pupil sizes of participants were measured while viewing target image. After viewing target image, participants rated immediately their emotional response to the target on a 7-point scale.The results indicated that the two classes of stimuli, IAPS and opener images, caused different variations in pupil sizes. The result of IAPS herein concerning the effect of emotion on pupil size is similar to that identified in prior research. However, product pictures yielded different results from IAPS pictures. The measurement of pupil size cannot distinguish between positive and neutral emotional responses. Negative emotional responses to products were reflected weaker than the other emotional responses. The pupillary responses were not similar viewing negative images of IAPS that pupillary variation was larger than neutral pictures. Taken together, the findings of this study support the claim that pupil size can be measured to assess products.Relevance to industrySince pupil size can be used to distinguish products that would elicit negative emotion, thus, on-line shopping service provider can measure customer's pupil size through laptop's camera to determine whether they dislike the product.