[The study of skewed staircase illusion].
When we look at a flight of level stairs where its longitudinal section obliquely intersected the direction of treads, we perceive the stairs to be tilted laterally. We call this phenomenon a "skewed staircase illusion (SSI)." To investigate features of the SSI, using miniatures of skewed stairs or of laterally sloped planes, we measured their apparent lateral tilts. Main findings were: 1) the stairs were perceived to be less tilted than the laterally sloped planes, 2) the stairs of 32 steps were perceived to be more tilted than those of five steps, 3) the stairs were perceived to be more tilted when we looked them down from the top than when we looked them up from the base, and 4) the apparent tilt of the skewed stairs or laterally sloped planes had a positive correlation with cross-component of slope. We proposed that the SSI is affected by an apparent plane generated by perceptual connection of the treads of stairs.
Tsuinashi
Seiichi
S
Department of Psychology, Graduate School of Letters, Ritsumeikan University, Tojiin, Kita-ku, Kyoto, Japan. gr010011@lt.ritsumei.ac.jp
D006801:Humans; D009903:Optical Illusions