Purchase this article with an account.
Alexander Bies, Atsushi Kikumoto, Stefanos Lazarides, Margaret Sereno; Shape constancy in anaglyphs: Effects of angle, context and instruction. Journal of Vision 2017;17(10):318. doi: 10.1167/17.10.318.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
When asked to draw a figure from perspective, many people inadvertently draw a shape representative of the figure's physical characteristics instead. This shape constancy effect has been studied extensively, yet questions remain about which 3-dimensional contextual cues are sufficient to elicit such effects, and whether, in a fully crossed design, the variables of context, instruction and angle interact. Here, we rendered quadrilateral surfaces as skeletal outlines embedded in a cuboid polyhedron or as an isolated shape, lacking texture and shading, rotated around the viewing plane, and converted them into anaglyphs. Participants were asked to report the shapes' physical and apparent width using a 6-alternative forced choice paradigm. Twelve participants each completed 440 trials, 2 repetitions of 11 angles of rotation of 3 object widths, 2 types of instruction and 2 levels of context. Statistical analyses averaging across repetitions and object width revealed a significant three-way interaction among rotation angle, instruction, and context. Participants were equivalently accurate at low levels of rotation and when judgment and context were consistent (e.g., physical width judgments were accurate for 3-dimensional shapes). When instructed judgment and level of context were inconsistent (i.e., judging the physical width of a quadrilateral or apparent width of a cuboid), participants made increasingly large errors (i.e., regression toward the real object and toward the apparent object, respectively). Results were replicated in a second experiment using the method of adjustment to capture width judgments. Although individuals can correctly estimate both real and apparent widths across rotation angle, errors arise with rotation under conditions of inconsistent instruction and context. In addition, binocular integration is sufficient to drive the perception of three-dimensional shape and elicit shape constancy effects from anaglyphs. Future studies of artistic ability and the effects of shape constancy may build on these results and new approach to measuring shape constancy.
Meeting abstract presented at VSS 2017
This PDF is available to Subscribers Only