Perception of Relative Depth Interval: Systematic Biases in Perceived Depth

Abstract

Given an estimate of the binocular disparity between a pair of points, and an estimate of the viewing distance, or knowledge of eye position, it should be possible to obtain an estimate of their depth separation. Here we show that, when points are arranged in different vertical geometric configurations across two intervals, many observers find this task difficult. Those who can do the task, tend to perceive the depth interval in one configuration as very different from depth in the other configuration. We explore two plausible explanations for this effect.The first is the tilt of the empirical vertical horopter: points perceived along an apparently vertical line correspond to a physical line of points tilted backwards in space. Second, the eyes can rotate in response to a particular stimulus. Without compensation for this rotation, biases in depth perception would result. We measured cyclovergence indirectly, using a standard psychophysical task, while observers viewed our depth configuration. Biases predicted from error due either to cyclovergence, or the tilted vertical horopter, were not consistent with the depth configuration results. Our data suggest that, even for the simplest scenes, we do not have ready access to metric depth from binocular disparity.

Vertical Size Disparity and the Correction of Stereo Correspondence

“…First, a relatively smaller slant for the two line patterns may be partly explained by the perspective cues contained by the stimuli (Banks and Backus 1998), because the arrangement of the elements contained by the two line patterns was regular, therefore suggesting the frontoparallel plane. Second, it may be related to a large individual difference in metric judgments about stereoscopic depth (Harris et al 2012). This issue will be discussed again in section 4.3.…”

Depth Perception Not Found in Human Observers for Static or Dynamic Anti-Correlated Random Dot Stereograms

“…Our first goal was to use a much larger sample of observers than has been tested before. Previous studies of slant perception [29] , motion in depth [30] , and relative depth intervals [31] have demonstrated the need to study individual differences in order to fully understand the underlying mechanisms of binocular depth perception [32] . Here, we use this approach to determine the extent to which reliable disparity discrimination can be found for ACRDS presented with a correlated background.…”

Shifts of the psychometric function: Distinguishing bias from perceptual effects

“…Finding out whether or not MSS can distinguish perceptual effects from response bias is important when one considers the extent to which this method is used in experimental psychology and, thus, the potential threat to the internal validity of research carried out with MSS. We should stress that MSS is used more often than it seems, as MSS is sometimes referred to as "single-interval, two-alternative forced-choice" (e.g., Bailey, Hodgson, & Hill, 1998;Harris, Chopin, Zeiner, & Hibbard, 2012;Loftus, Nicholls, Mattingley, Chapman, & Bradshaw, 2009) and other times as "two-alternative forced-choice" (e.g., Cheal, Lyon, & Hubbard, 1991;Davis & Kim, 2011;Prinzmetal, Zvinyatskovskiy, Gutierrez, & Dilem, 2009; for a discussion of the inadequacy of this latter term, see Morgan et al, 2012), although more often than not the use of MSS is simply described without giving it any name at all (e.g., Gast & Rothermund, 2010;Johnston & McCann, 2006;Morgan, Ward, & Castet, 1998;Wearden, Todd, & Jones, 2006). The purpose of this paper is to demonstrate the theoretical inability of MSS to distinguish response bias from perceptual effects and to discuss a simple and effective modification that can do so under some restrictive conditions.…”