Distinct processes of lighting priors for lightness and 3-D shape perception [post]

Yuki Kobayashi, Daniele Zavagno, Kazunori Morikawa
2020 unpublished
The visual system often relies on prior assumptions when interpreting ambiguous visual inputs. A well-known example is the light-from-above prior, which aids the judgment of an object's three-dimensional (3-D) shape (i.e., convex or concave). Recent studies have revealed that the light-from-above prior also helps solve lightness ambiguity. This study aimed to examine whether 3-D shape perception and lightness perception share the same lighting prior. The study participants performed two tasks:
more » ... rformed two tasks: one focusing on lightness perception and another focusing on 3-D shape perception. The dominant directions of the assumed lighting were calculated from participants' performance in the two tasks. The results showed that the assumed lighting direction for 3-D shape perception considerably shifted toward the left while the one for lightness perception was almost from directly above. The clear difference between these two directions supports the hypothesis that the visual system uses distinct lighting priors for 3-D shape perception and lightness perception. Japanese and European observers then replicated these results, indicating that the lighting priors are universal regardless of reading/writing direction.
doi:10.31234/osf.io/u8xtw fatcat:bfmxlm2mdvdhlp3y7zyy4thx2e