Pupil Dilation, Emotion Valence, and Recall of Visual Images

Visual Images (pleasant and unpleasant) has a significant role in cognitive processing. Visual design disciplines intentionally create affective products and images that influence user's behavior. Thus, it is vital to understand the human factors involved in processing pleasant, unpleasant, and neutral images. Pupillometry is one such feature tomeasure the psychological process sensitive to the visual stimulus. This study examines the role of the affective images on pupil dilation and recall. Thirty graduates from a technical institute participated in the study. They were shown pictures that varied across emotional valence (pleasant and unpleasant) and also across categories (child, adult, animal, and landscape). Eye-tracking was used to capture pupil size variation in response to the emotional valence of the stimuli. The participants were later asked to recall the pictures. Bayesian model comparison using Bayes Factors approach was utilized for analyzing data. Results did not produce evidence for the main effect of either emotional valence or picture category; instead, the interaction of both influenced pupil size and recall. The cross-over interaction is discussed in light of the previous finding in the literature.