Perceived slant of binocularly viewed large-scale surfaces: A common model from explicit and implicit measures

Abstract

It is known that the perceived slants of large distal surfaces, such as hills, are exaggerated and that the exaggeration increases with distance. In a series of two experiments, we parametrically investigated the effect of viewing distance and slant on perceived slant using a high-fidelity virtual environment. An explicit numerical estimation method and an implicit aspect ratio approach were separately used to assess the perceived optical slant of simulated large-scale surfaces with different slants and viewing distances while gaze direction was fixed. The results showed that perceived optical slant increased logarithmically with viewing distance and the increase was proportionally greater for shallow slants. At each viewing distance, perceived optical slant could be approximately fit by linear functions of actual slant that were parallel across distances. These linear functions demonstrated a fairly constant gain of about 1.5 and an intercept that increased logarithmically with distance. A comprehensive three-parameter model based on the present data provides a good fit to a number of previous empirical observations measured in real environments.

Pitching people with an inversion table: Estimates of body orientation are tipped as much as those of visual surfaces

“…These overestimates seem slightly more pronounced at angles of greater than 24°. This is similar to the results of Li and Durgin (2010), who modeled the slant data of Proffitt et al (1995). Our results are consistent with previous work showing that people overestimate how much they are tilted backward when asked to estimate when they are tilted backward at 45° (Ito & Gresty, 1997;Jewell, 1998).…”

“…For instance, recently, measures of matching extent and remote haptic perception have been supportive of a single underlying representation that is exaggerated to the same extent as the results are for verbal and visual matching estimates Shaffer & McManama, 2015). Li and Durgin (2010) had one group of people compare the relative length of a frontal extent to that of an extent that was placed up a virtual hill (tilted back in depth). This provides, by trigonometry, an implicit estimate of perceived slant.…”

“…We have shown that the gain of proximal slant, or the perceived orientation of one's own body at the five different angles, is similar to the gains seen for the verbal estimates of visually perceived distal slanted surfaces. The model of Li and Durgin (2010) is based on their work showing that people's perceived declination of gaze has a gain of about 1.5. So in order to see the ground plane as horizontal, we expand the scale of the ground by a factor of 1.5 to perceive it as being horizontal.…”

“…Finally, we sought to investigate whether the pattern of results we would find for proximal slant or the perceived orientation of one's own body at the five different angles is similar to the pattern seen for the verbal estimates of distal slanted surfaces. Li and Durgin (2010) developed a model that predicted that surfaces would be overestimated by a factor of 1.5. They found that virtual surfaces with viewing distances of between 1 and 16 m were overestimated by a factor of 1.5, with longer viewing distances resulting in larger slant bias, and this model provided an excellent fit to the verbal overestimates of eight natural outdoor hills reported by Proffitt et al (1995).…”

Palm board and verbal estimates of slant reflect the same perceptual representation

“…For the last two decades, people have verbally overestimated the slant of visually perceived geographical, virtual, and manmade hills by between 5°and 25° (Bhalla & Proffitt, 1999;Creem-Regehr, Gooch, Sahm, & Thompson, 2004;Durgin, Hajnal, Li, Tonge, & Stigliani, 2010;Hajnal, Abdul-Malak, & Durgin, 2011;Li & Durgin, 2010;Proffitt, Bhalla, Gossweiler, & Midgett, 1995;Shaffer & Flint, 2011;Shaffer, McManama, Swank, Williams, & Durgin, 2014;Stigliani, Li, & Durgin, 2013). Two additional measures have also been used in several of these studies.…”