Search PubMed⌕ Search

PubMed · 15693662

Combining cues while avoiding perceptual conflicts.

Abstract

A common assumption in cue combination models is that small discrepancies between cues are due to the limited resolution of the individual cues. Whenever this assumption holds, information from the separate cues can best be combined to give a single, more accurate estimate of the property of interest. We examined whether information about the discrepancy itself is lost when this is done. In our experiments, subjects were required to combine cues to match certain properties while avoiding perceptual conflicts. In part 1, they combined expansion and change in disparity to estimate motion in depth; and in part 2, they combined perspective and binocular disparities to estimate slant. We compared the pattern in the way that subjects set the two cues with the patterns predicted by models of cue combination with and without a loss of information about the discrepancy. From this comparison we conclude that little information about the discrepancies between cues is lost when the cues are combined.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Maarten A Hogervorst, Eli Brenner. 2004. Combining cues while avoiding perceptual conflicts.. https://doi.org/10.1068/p5253

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Resolution for spatial segregation and spatial localization by motion signals.

We investigated two types of spatial resolution for perceiving motion-defined contours: grating acuity, the capacity to discriminate alternating stripes of opposed motion from transparent bi-directional motion; and alignment acuity, the capacity to localize the position of motion-defined edges with respect to stationary markers. For both tasks the stimuli were random noise patterns, low-pass filtered in the spatial dimension parallel to the motion. Both grating and alignment resolution varied systematically with spatial frequency cutoff and speed. Best performance for grating resolution was about 10 c/deg (for unfiltered patterns moving at 1-4 deg/s), corresponding to a stripe resolution of about 3'. Grating resolution corresponds well to estimates of smallest receptive field size of motion units under these conditions, suggesting that opposing signals from units with small receptive fields (probably located in V1) are contrasted efficiently to define edges. Alignment resolution was about 2' at best, under similar conditions. Whereas alignment judgment based on luminance-defined edges is typically 3-10 times better than resolution, alignment based on motion-defined edges is only 1.1-1.5 times better, suggesting motion contours are less effectively encoded than luminance contours.

Cues↗

Pictorial cues constrain depth in da Vinci stereopsis.

"da Vinci stereopsis" is defined as depth seen in a monocular object occluded by a binocular one, and the visual system must solve its depth ambiguity [Nakayama, K., & Shimojo, S. (1990). da Vinci stereopsis: Depth and subjective occluding contours from unpaired image points. Vision Research, 30, 1811-1825]. Although fused images include various pictorial features, effects of pictorial depth cues have never been systematically investigated in da Vinci stereopsis. To examine this, we created stereograms consisting of a monocular bar flanked by binocular bars with a fixed large horizontal separation, in which the monocular bar induced a subjective occluding edge. Manipulating vertical size or contrast of the bars could affect the depth of the monocular bar. Conflicting these cues revealed that the effect of vertical size was stronger than that of contrast in all our subjects. Measurements of the depth indicated that the relative vertical size of the bars quantitatively determined the perceived depth, of which levels had large inter-subject differences. All these experiments indicate that the visual system can use the pictorial depth cues as a constraint to determine the depth of monocular elements.

Cues↗

Direction and distance deficits in path integration after unilateral vestibular loss depend on task complexity.

The effects of peripheral vestibular disorders on the direction and distance components of the internal spatial representation were investigated. The ability of Menière's patients to perform path integration was assessed in different situations aimed at differentiating the level of spatial processing (simple versus complex tasks), the available sensory cues (proprioceptive, vestibular, or visual conditions), and the side of the path (towards the healthy versus the lesioned side). After exploring two legs of a triangle, participants were required either to reproduce the exploration path, to follow the reverse path, or to take a shortcut to the starting point of the path (triangle completion). Patients' performances were recorded before unilateral vestibular neurotomy (UVN) and during the time-course of recovery (1 week and 1 month) and were compared to those of matched control subjects tested at similar time intervals. Both the angular and linear path components of the trajectory were impaired for patients compared to controls. However, deficits were restricted to the complex tasks, which required a higher level of spatial processing. Most deficits were maximal 1 week after UVN, and some remained up to the first post-operative month. Spatial representation was differentially impaired according to the available sensory cues: deficits were absent in active locomotor blindfolded condition, appeared in conditions involving visual and vestibular information, and were maximal when visual cues alone were available. Finally, concerning the side of the path, unilateral vestibular loss led to global impairment of the internal spatial representation, yet some asymmetrical spatial performances were observed 1 week after UVN. On the whole, results suggest that the environment experienced by the patients is different after UVN and that a different internal spatial representation is constructed, especially for tasks requiring high levels of spatial processing.

Cues↗