Abstract
Introduction Preference for curvature, the curvature effect, seems to transcend cultures, species, and stimulus kinds. However, its psychological mechanisms remain obscure because studies often overlook the complexity of the features characterizing contour and disregard personal and contextual factors. To unpack the curvature effect, we manipulated geometric features continuously and multidimensionally, and examined perceptual and hedonic judgments at the group and individual levels using two contrasting paradigms. As curved contours are more easily perceived and processed than polygons, we hypothesized that perceived contour might explain liking better than geometric features. Method Eighty-seven participants judged online 88 novel stimuli from the Visual Contour (VC) open-source set varying in the number of vertexes, the distance between vertexes, and the tension of the spline linking adjacent vertexes. In Paradigm 1, participants rated their liking and perceived contour using a slider. In Paradigm 2, using the method of constant stimuli, participants decided whether the target contour was more curved/angular than, and whether they preferred it, to the reference with median tension, controlling for vertexes and distance. Results Perceptual and hedonic judgments relied on vertexes, distance, and tension, but their specific impact depended on the person and the judgment kind—whether perceptual or hedonic. The multidimensional manipulation also revealed the interaction between two constructs: contour and shape. Crucially, the curvature effect was not robust across binary comparisons and continuous manipulations. Regarding our hypothesis, the association between perceptual and hedonic ratings depended on shape categorization, determined by distance. Finally, art experience, openness to experience, and need for cognition moderated how people used each feature in perceptual and hedonic judgments. Conclusion Research on perception and appreciation of contour and shape should factor in their complexity and defining features. Additionally, embracing individual sensitivities opens avenues for a better understanding of psychological phenomena.