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Journal Article 7.1: Kavšek, M., & Granrud, C. E. (2012). Children’s and adults’ size estimates at near and far distances: A test of the perceptual learning theory of size constancy development. i-Perception, 3(7), 459-466. doi:10.1068/i0530

Abstract: This study tested the perceptual learning theory of size constancy development, which proposes that children younger than 9 years are relatively insensitive to monocular cues for distance and size, and that developmental changes in far-distance size estimation result from increasing sensitivity to these cues. This theory predicts that before 10 years, children will make less accurate size judgments at far distances under monocular than under binocular viewing conditions. Five age groups were tested: 5–6, 7–8, 9–10, 19–28, and 50+ years. Participants judged the size of a standard disc, from viewing distances of 6.1 and 61 m, by pointing at 1 of 9 nearby comparison discs. Testing was conducted under both monocular and binocular viewing conditions. Five- to six-year-olds underestimated object size at the far distance, 7- to 8-, 9- to 10-year-olds, and older adults made size estimates that were close to accurate, and the young adults significantly overestimated size. At the near distance, all age groups underestimated size and no age differences were found. Contrary to predictions from the perceptual learning theory, viewing condition had no significant effect on size estimates.

Journal Article 7.2: Palmer, S. E., & Ghose, T. (2008). Extremal edge: A powerful cue to depth perception and figure-ground organization. Psychological Science, 19(1), 77-83. doi:10.1111/j.1467-9280.2008.02049.x

Abstract: Extremal edges (EEs) are projections of viewpoint-specific horizons of self-occlusion on smooth convex surfaces. An ecological analysis of viewpoint constraints suggests that an EE surface is likely to be closer to the observer than the non-EE surface on the other side of the edge. In two experiments, one using shading gradients and the other using texture gradients, we demonstrated that EEs operate as strong cues to relative depth perception and figure-ground organization. Image regions with an EE along the shared border were overwhelmingly perceived as closer than either flat or equally convex surfaces without an EE along that border. A further demonstration suggests that EEs are more powerful than classical figure-ground cues, including even the joint effects of small size, convexity, and surroundedness.

Journal Article 7.3: Proffitt, D. R. (2006). Distance perception. Current Directions in Psychological Science, 15(3), 131-135. doi:10.1111/j.0963-7214.2006.00422.x

Abstract: Distance perception seems to be an incredible achievement if it is construed as being based solely on static retinal images. Information provided by such images is sparse at best. On the other hand, when the perceptual context is taken to be one in which people are acting in natural environments, the informational bases for distance perception become abundant. There are, however, surprising consequences of studying people in action. Nonvisual factors, such as people’s goals and physiological states, also influence their distance perceptions. Although the informational specification of distance becomes redundant when people are active, paradoxically, many distance-related actions sidestep the need to perceive distance at all.

Journal Article 7.4: Vishwanath, D., & Hibbard, P. B. (2013). Seeing in 3-D with just one eye: Stereopsis without binocular vision. Psychological Science, 24(9), 1673-1685. doi:10.1177/0956797613477867

Abstract: Humans can perceive depth when viewing with one eye, and even when viewing a two-dimensional picture of a three-dimensional scene. However, viewing a real scene with both eyes produces a more compelling three-dimensional experience of immersive space and tangible solid objects. A widely held belief is that this qualitative visual phenomenon (stereopsis) is a by-product of binocular vision. In the research reported here, we empirically established, for the first time, the qualitative characteristics associated with stereopsis to show that they can occur for static two-dimensional pictures without binocular vision. Critically, we show that stereopsis is a measurable qualitative attribute and that its induction while viewing pictures is not consistent with standard explanations based on depth-cue conflict or the perception of greater depth magnitude. These results challenge the conventional understanding of the underlying cause, variation, and functional role of stereopsis.