Abstract
Objective: The features of figures are not perceived independently in visual images but are influenced by their contexts, for example, the Jastrow illusion. Here we reported a new visual illusion which reflects the influence of higher level object configuration on its local features. Methods: In five experiments, participants were required to adjust the length of a straight line until its length equalized to a target curve’s length. Target curve was set to be the concave (50% of trials) or convex (50% of trials) edge of a crescent shape (the length of concave edge is shorter than that of convex edge; Experiments 1, 2, 3, and 4), or one of the two separate curves of a decomposed crescent shape (Experiment 5). Results: A novel length illusion was revealed: When crescent objects were the tested stimuli (Experiments 1-4), a curve was perceived shorter when being as the convex edge than being as the concave edge. In contrast, when the two separated curves were the tested stimuli (Experiment 5), a contrast effect was revealed: The length of a curve was perceived shorter when being as the shorter one of the two separated curves than being as the longer one. Conclusion: The results suggest that the object-based perception affects the length perception of crescent edges. It is rather strong such that it overwhelms the contrast effect emerging in the separate-curves condition.
Meeting abstract presented at VSS 2013