Academic journal article Attention, Perception and Psychophysics

Predominance of Ground over Ceiling Surfaces in Binocular Rivalry

Academic journal article Attention, Perception and Psychophysics

Predominance of Ground over Ceiling Surfaces in Binocular Rivalry

Article excerpt

The superiority of ground surfaces over ceiling surfaces in determining the representation of the visual world, demonstrated in several studies of visual perception and visual search, has been attributed to a preference for top-away projections resulting from ecological constraints. Recent research on binocular rivalry indicates that ecological constraints affect predominance relations. The present study considered whether there is a difference in predominance between ground and ceiling surfaces. In Experiment 1, we examined whether a ground surface would dominate a ceiling surface when one surface was presented to each eye. In Experiment 2, we used an eye-swapping paradigm to determine whether a ground surface would come to dominance faster than a ceiling surface when presented to the suppressed eye. The eye-swapping paradigm was used again in Experiment 3, but the ground and ceiling planes were replaced with frontal planes with similar variations in texture density. The results of these experiments indicate that ground surfaces are predominant over ceiling surfaces, with this predominance affecting both the dominance and suppression phases of binocular rivalry. This superiority of ground planes is independent of image properties such as the increase or decrease in texture density from the lower half to the upper half of the images.

When dissimilar images are presented to the two eyes, visual awareness may fluctuate between the two images, resulting in the perception of one image at a time rather than both images fused. This phenomenon is known as binocular rivalry (Wheatstone, 1838). The image perceived at a given moment in time is referred to as the dominant image, the other image as the suppressed image. Where in the visual hierarchy the competition between two dissimilar images is resolved is still a debated issue (Blake & Logothetis, 2002). Fundamental to this debate is the issue of whether rivalry takes place over eye-based representations as a result of low-level interactions between monocular channels, or over stimulus-based representations as a result of competing visual representations at higher brain areas (Lee & Blake, 1999; Logothetis, Leopold, & Sheinberg, 1996). Recent studies suggest that binocular rivalry arises as a result of distributed processes occurring at different levels of the visual pathway (Freeman, 2005; Nguyen, Freeman, & Alais, 2003; Ooi & He, 2003; Wilson, 2003).

Since Levelt's (1965) observation that suppression durations are influenced by stimulus strength, various image properties that affect binocular rivalry have been identified (for a comprehensive review, see Blake, 2001). Evidence about the interaction between stimulus strength and dominance and suppression durations led to the so-called "bottom-up" theory of binocular rivalry. Blake (1989) formalized a bottom-up model in which inhibitory connections between monocular channels determined perceptual alternations in binocular rivalry. Recent fMRI studies found that interocular competition was resolved in the monocular neurons in the blind spot (Tong & Engel, 2001) and in V1 (Polonsky, Blake, Braun, & Heeger, 2000), or even in the lateral geniculate nucleus (LGN; Haynes, Deichmann, & Rees, 2005; Wunderlich, Schneider, & Kastner, 2005), supporting Blake's (1989) model.

There is contradictory evidence, however, supporting stimulus-based representations. Using single-unit recordings from monkeys, Leopold and Logothetis (1996) showed that perception-dependent activation increases at higher levels in the visual cortex with little activation in monocular neurons within V1. In addition, when Logothetis et al. (1996) flickered images on and off at 18 Hz while images were switching between the eyes of their observers every 333 msec, they found that their observers experienced stable percepts with temporal dynamics similar to those in conventional rivalry experiments. As a result, Logothetis et al. …

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