The Influence of Surface Roughness and Surface Size on Perceived Pleasantness.

Objects’ material properties are essential not only in how we use and interact with them but also in eliciting affective responses when in contact with the body. Such affective experiences are of particular interest because they likely strongly impact our daily interactions with materials. We examined whether exploration time and surface size could influence affective responses to rough stimuli. Here, participants made pleasantness and arousal judgments after actively exploring sandpaper stimuli of different sizes with varying roughness levels under different time constraints. Findings confirm that increased surface roughness is associated with decreased perceived pleasantness; however, arousal did not systematically covary with roughness. We didn’t find an effect of exploration time on perceived pleasantness or arousal, but there were interactions between grit size and surface size. Overall, the direction of the effects of grit size on pleasantness was similar for both surface sizes. However, the slopes of increase in pleasantness relative to grit size varied depending on surface size. Effects on arousal were unrelated and small. We suggest that exploration time had little influence on the perceived magnitude of affective reactions to roughness. However, surface size may influence not only perceived roughness but also the perceived pleasantness of rough stimuli.