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1.
A question raised a long time ago in binocular rivalry research is whether the phenomenon of binocular rivalry is purely determined by local stimulus properties or that global stimulus properties also play a role. More specifically: do coherent features in a stimulus influence rivalrous behavior? After decades of underexposure of the subject, recently this question seemed to be answered in the affirmative. This paper presents additional evidence for an influence of coherent features. In an experiment in which eye movements cannot bias conclusions it is demonstrated that Gestalt formation influences binocular rivalry positively, i.e., stronger Gestalts have longer total dominance times. Gestalt formation appears to intervene in the states of dominance ("what"), not directly in the dominance durations ("how long"). This generates questions about the nature of interactions between binocular rivalry and Gestalt formation. Gestalt formation seems to be fed by signals that are generated after binocular convergence and only leaves its mark on binocular rivalry by feedback to monocular channels, a conclusion which has been drawn before by Alais and Blake [Alais, D., & Blake, R. (1998). Interaction between global motion and local binocular rivalry. Vision research 38, 637-644].  相似文献   

2.
Lee SH  Blake R 《Vision research》2004,44(10):983-991
During binocular rivalry, observers sometimes perceive one complete visual object even though component features of that perceptually dominant object are distributed between the two eyes and are in rivalry against other, dissimilar features. This interocular grouping cannot be explained by models of rivalry in which one eye or the other is completely dominant at any given moment. But perhaps global interocular grouping is achieved by simultaneous local eye dominance, wherein portions of one eye's view and complementary portions of the other eye's view become dominant simultaneously. To test this possibility, we performed two experiments using relatively large, complex figures as rival targets. In one experiment we used an "eye-swap" technique to confirm that within given, local spatial regions of rivalry it was the region of an eye--not a given stimulus feature--that was usually dominant. In a second experiment, we measured dominance durations for multiple, local zones of rivalry and then created 1-min animations of a global "montage" in which dominance within local regions was governed by the distributions of dominance measured empirically. These animations included significant periods of time during which global interocular grouping was evident; observers viewed these animations intermixed with actual rivalry displays, and the resulting tracking data confirmed the similarity in global dominance of the two display types. Thus interocular grouping during rivalry does not rule out local, eye-based rivalry, although synergistic and top-down influences almost certainly provide additional force in the promotion of interocular grouping.  相似文献   

3.
In the past decade, effects of pattern coherence have indicated that perception during binocular rivalry does not result solely from reciprocal inhibitory competition between monocular channels. In this study we were interested in feature selectivity both during dominance and during suppression. The first experiment shows that a suppressed stimulus perceptually appears earlier when it shares features with a visible stimulus than when it does not. Subsequently, our second experiment suggests a reversal of this effect when similarity is exhibited with a suppressed stimulus. These findings hint at a role for both selective enhancing (Experiment 1) and selective inhibitory cortical mechanisms (Experiment 2) in causing image rivalry. From a phenomenological perspective these results suggest that we are not only selectively aware but also selectively unaware of specific features in the visual scene.  相似文献   

4.
When the two eyes are presented with sufficiently different stimuli, the stimuli will engage in binocular rivalry. During binocular rivalry, a subject's perceptual state alternates between awareness of the stimulus presented to the right eye and that presented to the left eye. There are instances in which competition is not eye-based, but instead takes place between stimulus features, as is the case in flicker and switch rivalry (F&S). Here we investigate another such instance, interocular grouping, using a Diaz-Caneja type stimulus in conjunction with synchronous stimulus flicker. Our results indicate that stimulus flicker increases the total duration of interocularly bound percepts, and that this effect occurs for a range of temporal flicker frequencies. Furthermore, the use of contrast-inversion flicker causes a decrease of total dominance duration of the interocularly bound percepts. We argue that different flickering regimes can be used to differentially stimulate lower and higher levels of visual processing involved in binocular rivalry. We propose that the amount of interocularly combined pattern-completed percept can be regarded as a measure of the level at which binocular rivalry is resolved.  相似文献   

5.
When dissimilar images are presented to the two eyes, the human visual system lapses into binocular rivalry, a unique perceptual state characterized by stochastic alternations in dominance of one of the two source images over the other. Probe targets delivered to an eye during suppression phases are more difficult to detect than probes delivered during dominance phases. Nearly all probe studies have involved presenting new stimulation (e.g., a spot of light) either superimposed on or replacing the suppressed stimulus. Here, we ask whether observers can detect a reduction in the contrast of the suppressed stimulus itself. In other words, can observers detect a probe that should make an already invisible stimulus even weaker? Specifically, we compared observers’ ability to detect contrast increments and contrast decrements introduced within a rival pattern during dominance and suppression. Contrast increment thresholds were elevated across all pedestal contrasts when the increment was introduced during suppression compared to during dominance, replicating previous results. Contrast decrement thresholds measured during suppression were elevated to an even greater extent, but the fact that they were obtained at all establishes that observers were able to detect probes that should make an already invisible target even more difficult to perceive. In a second experiment, we found a similar pattern of results for contrast change detection in complex images of faces as well. Based on the resulting threshold-vs.-contrast functions, we suggest that, regardless of the complexity of the image, rivalry suppression modulates the neural contrast response function through a mixture of reduced overall response gain and a shift in the contrast gain.  相似文献   

6.
We examined whether interocular inhibition in binocular rivalry could occur at the interocular intersection of horizontal and vertical rectangular patches which are locally fusible but globally rivalrous between the two eyes. We measured contrast increment (and decrement) thresholds of a monocularly presented probe which was presented on the horizontal patch corresponding to the intersection. We found that the threshold was higher when the horizontal patch was perceptually suppressed than when it was dominant. In addition, threshold elevation did not occur when both patches were dominant, or when the horizontal patch was viewed in isolation. These results indicate that interocular inhibition occurs at the potentially fusible region, and the determination of binocular fusion or binocular rivalry does not depend on physical stimulus but rather perceptual state at the time.  相似文献   

7.
Li DF  Freeman AW  Alais D 《Vision research》2005,45(10):1255-1263
Binocular rivalry, which is induced by presenting the two eyes with incompatible stimuli, results in periods where one eye's stimulus is seen and the other stimulus is suppressed. We measured the depth of suppression in two ways, with very different results. First, two similar forms were briefly presented to one eye: the difference in shapes required to discriminate the forms was substantially greater during suppression than during dominance. Second, the two forms were made sufficiently different in shape to be easily distinguishable at high contrast, and contrast was lowered to find the threshold for discrimination of the forms. Contrast sensitivity did not differ between the suppression and dominance states. These results were replicated with a motion discrimination task: suppression markedly worsened the ability to distinguish increases from decreases in speed but did not elevate the minimum contrast required for the same task. We interpret the results in terms of steep contrast-response functions in visual cortex beyond the primary area.  相似文献   

8.
When each eye is confronted with a dissimilar stimulus, the percept will generally alternate between the two. This phenomenon is known as binocular rivalry. Although binocular rivalry occurs at locations where targets overlap spatially, the area surrounding rivalrous targets can modulate their dominance. Here we show that during binocular rivalry of oppositely moving gratings, a surrounding grating moving in the same direction as one of the two leads to increased dominance of the opposite direction of motion in the center. This increased dominance of the opposite direction in the center was observed irrespective of the eye to which the surround was presented. Inspection of the results for different conditions reveals that the preference for the opposite direction of motion cannot be explained by a single mechanism operating beyond binocular fusion. We therefore suggest that this phenomenon is the outcome of center-surround interactions at multiple levels along the pathway of visual motion processing.  相似文献   

9.
Chong SC  Blake R 《Vision research》2006,46(11):1794-1803
We investigated the influence of exogenous and endogenous attention on initial selection in binocular rivalry. Experiment 1 used superimposed +/-45 degrees gratings viewed dioptically for 3s, followed by a brief contrast increment in one of the gratings to direct exogenous attention to that grating. After a brief blank period, dichoptic stimuli were presented for various durations (100-700 ms). Exogenous attention strongly influenced which stimulus was initially dominant in binocular rivalry, replicating an earlier report (Mitchell, Stoner, & Reynolds. (2004). Object-based attention determines dominance in binocular rivalry. Nature, 429, 410-413). In Experiment 2, endogenous attention was manipulated by having participants track one of two oblique gratings both of which independently and continuously changed their orientations and spatial frequencies during a 5s period. The initially dominant grating was most often the one whose orientation matched the grating correctly tracked using endogenous attention. In Experiment 3, we measured the strength of both exogenous and endogenous attention by varying the contrast of one of two rival gratings when attention was previously directed to that grating. The contrast of the attended grating had to be reduced by an amount in the neighborhood of 0.3 log-units, to counteract attention's boost to initial dominance. Evidently both exogenous and endogenous attention can influence initial dominance of binocular rivalry, effectively boosting the stimulus strength of the attended rival stimulus.  相似文献   

10.
Stochastic resonance in binocular rivalry   总被引:7,自引:0,他引:7  
When a different image is presented to each eye, visual awareness spontaneously alternates between the two images--a phenomenon called binocular rivalry. Because binocular rivalry is characterized by two marginally stable perceptual states and spontaneous, apparently stochastic, switching between them, it has been speculated that switches in perceptual awareness reflect a double-well-potential type computational architecture coupled with noise. To characterize this noise-mediated mechanism, we investigated whether stimulus input, neural adaptation, and inhibitory modulations (thought to underlie perceptual switches) interacted with noise in such a way that the system produced stochastic resonance. By subjecting binocular rivalry to weak periodic contrast modulations spanning a range of frequencies, we demonstrated quantitative evidence of stochastic resonance in binocular rivalry. Our behavioral results combined with computational simulations provided insights into the nature of the internal noise (its magnitude, locus, and calibration) that is relevant to perceptual switching, as well as provided novel dynamic constraints on computational models designed to capture the neural mechanisms underlying perceptual switching.  相似文献   

11.
When dissimilar stimuli are presented to each eye, perception alternates between both images--a phenomenon known as binocular rivalry. It has been shown that stimuli presented in proximity of rival targets modulate the time each target is perceptually dominant. For example, presenting motion to the region surrounding the rival targets decreases the predominance of the same-direction target. Here, using a stationary concentric grating rivaling with a drifting grating, we show that a drifting surround grating also increases the depth of binocular rivalry suppression, as measured by sensitivity to a speed discrimination probe on the rival grating. This was especially so when the surround moved in the same direction as the grating, and was slightly weaker for opposed directions. Suppression in both cases was deeper than a no-surround control condition. We hypothesize that surround suppression often observed in area MT (V5)-a visual area implicated in visual motion perception-is responsible for this increase in suppression. In support of this hypothesis, monocular and binocular surrounds were both effective in increasing suppression depth, as were surrounds contralateral to the probed eye. Static and orthogonal motion surrounds failed to add to the depth of rivalry suppression. These results implicate a higher-level, fully binocular area whose surround inhibition provides an additional source of suppression which sums with rivalry suppression to effectively deepen suppression of an unseen rival target.  相似文献   

12.
We used binocular rivalry as a psychophysical probe to explore center-surround interactions in orientation, motion and color processing. Addition of the surround matching one of the rival targets dramatically altered rivalry dynamics. For all visual sub-modalities tested, predominance of the high-contrast rival target matched to the surround was greatly reduced-a result that disappeared at low contrast. At low contrast, addition of the surround boosted dominance of orientation and motion targets matched to the surround. This contrast-dependent modulation of center-surround interactions seems to be a general property of the visual system and may reflect an adaptive balance between surround suppression and spatial summation.  相似文献   

13.
A previous study has shown that diverting attention from binocular rivalry to a visual distractor task results in a slowing of rivalry alternation rate between simple orthogonal orientations. Here, we investigate whether the slowing of visual perceptual alternations will occur when attention is diverted to an auditory distractor task, and we extend the investigation by testing this for two kinds of binocular rivalry stimuli and for the Necker cube. Our results show that doing the auditory attention task does indeed slow visual perceptual alternations, that the slowing effect is a graded function of attentional load, and that the attentional slowing effect is less pronounced for grating rivalry than for house/face rivalry and for the Necker cube. These results are explained in terms of supramodal attentional resources modulating a high-level interpretative process in perceptual ambiguity, together with a role for feedback to early visual processes in the case of binocular rivalry.  相似文献   

14.
We studied the effects of visual grouping on binocular rivalry in the left and right hemispheres of a split-brain observer, JW. In Experiments 1 and 2, we compared responses to traditional rivalry stimuli (e.g., a red vertical grating presented to the left eye and a green horizontal grating presented to the right eye) with responses to Diaz-Caneja stimuli (i.e., half of each grating was presented to one eye and the other half to the other eye). As found for intact-brain observers, JW reported episodes of exclusive visibility of coherent stimuli (e.g., of a red vertical grating alternating with a green horizontal grating) with Diaz-Caneja stimuli that were fewer and briefer than with traditional stimuli. This occurred in both hemispheres, demonstrating that during binocular rivalry, contours from one eye can be grouped with those of the opposite eye to create a coherent percept, even in the isolated hemispheres of the split-brain observer. In Experiment 3, we studied the tendency of rivalry in adjacent patches to synchronize. When both patches were in one of JW's hemifields, rivalry synchronized for similarly oriented stimuli, the same as happened for intact-brain observers. When the patches were in JW's opposite hemifields, there was no synchronizing of rivalry, unlike what happened for intact-brain observers. This suggests that rivalry processed in JW's two hemispheres is independent. We conclude that rivalry is processed fully within each hemisphere.  相似文献   

15.
Nguyen VA  Freeman AW  Alais D 《Vision research》2003,43(19):2003-2008
Binocular rivalry refers to the alternating perception that occurs when the two eyes are presented with incompatible stimuli: one monocular image is seen exclusively for several seconds before disappearing as the other image comes into view. The unseen stimulus is physically present but is not perceived because the sensory signals it elicits are suppressed. The neural site of this binocular rivalry suppression is a source of continuing controversy. We psychophysically tested human subjects, using test probes designed to selectively activate the visual system at a variety of processing stages. The results, which apply to both form and motion judgements, show that the sensitivity loss during suppression increases as the subject's task becomes more sophisticated. We conclude that binocular rivalry suppression is present at a number of stages along two visual cortical pathways, and that suppression deepens as the visual signal progresses along these pathways.  相似文献   

16.
We examined whether dynamic stimulation that surrounds a rival target influences perceptual alternations during binocular rivalry. We presented a rival target surrounded by dynamic random-dot patterns to both eyes, and measured dominance durations for each eye’s rival target. We found that rival target dominance durations were longer when surrounds were dynamic than when they were static or absent. Additionally, prolonged dominance durations were more apparent when the dynamic surround was alternately presented between the two eyes than when it was presented simultaneously to both eyes. These results indicate that dynamic stimulation that surrounds a rival target plays a role in maintaining the current perceptual state, and causes less perceptual alternations during binocular rivalry. Our findings suggest that dynamic signals on the retina may suppress rivalry, and thus provide useful information for stabilizing perceptions in daily life.  相似文献   

17.
Mishra J  Hillyard SA 《Vision research》2009,49(10):1073-1161
Directing attention to one of two superimposing surfaces composed of dot fields rotating in opposing directions facilitates processing of brief translations of the attended surface [Valdes-Sosa, M., Bobes, M. A., Rodriguez, V., & Pinilla, T. (1998). Switching attention without shifting the spotlight object-based attentional modulation of brain potentials. Journal of Cognition and Neuroscience, 10(1), 137-151]. Here we used ERP recordings to investigate the mechanisms of endogenous attentional selection of such competing dot surfaces under conditions of dichoptic viewing (one surface to each eye) and monocular viewing (both surfaces to one eye). Under dichoptic conditions, which induced binocular rivalry, translations of the attended surface presented to one eye elicited enhanced visual P1 and N1 ERP components relative to translations of the unattended surface presented to the other eye. In comparison, during monocular viewing the attended surface translations elicited a significantly larger N1 component in the absence of any P1 modulation. These results indicate that processing of the attended surface is biased at an earlier level in extrastriate visual cortex under conditions of inter-ocular versus intra-ocular competition.  相似文献   

18.
Sobel KV  Blake R 《Vision research》2003,43(14):1533-1540
Binocular rivalry probably involves distributed neural processes, some responsible for dominance, others for suppression and still others for fluctuations in perception. Focusing on the suppression process, the present study asks whether neural events underlying rivalry suppression take place prior to, or subsequent to those underlying the synthesis of subjective contours. Specifically, we examined whether (i) a subjective contour could prematurely return a suppressed target to dominance and (ii) whether suppression of a Kanizsa-type inducer precludes the formation of a subjective contour. Suppression durations were not abbreviated by the subjective contour, but suppression did prevent the formation of a subjective contour. Evidently suppression precedes the synthesis of subjective contours in the visual processing hierarchy.  相似文献   

19.
Visual rivalry is thought to be a distributed process that simultaneously takes place at multiple levels in the visual processing hierarchy. Also, the different types of rivalry, such as binocular and monocular rivalry, are thought to engage shared underlying mechanisms. We hypothesized that the amount of perceptual suppression during rivalry as measured by the total duration of fully exclusive perceptual dominance is determined by a distance in a neurally represented feature space. This hypothesis can be contrasted with the possibility that the brain constructs an internal model of the outside world using full-fledged object representations, and that perceptual suppression is due to an appraisal of the likelihood of the particular stimulus configuration at a high, object-based level. We applied color and stereo-depth differences between monocular rivalry stimulus gratings, and manipulated color and eye-of-origin information in binocular rivalry using the flicker & switch presentation paradigm. Our data show that exclusivity in visual rivalry increases with increased difference in feature space without regard for real-world constraints, and that eye-of-origin information may be regarded as a segregating feature that functions in a manner similar to color and stereo-depth information. Moreover, distances defined in multiple feature dimensions additively and independently increase the amount of perceptual exclusivity and coherence in both monocular and binocular rivalry. We conclude that exclusivity in visual rivalry is determined by a distance in feature space that is subtended by multiple stimulus features.  相似文献   

20.
Both monocular and binocular signals contribute to motion rivalry   总被引:1,自引:0,他引:1  
Meng X  Chen Y  Qian N 《Vision research》2004,44(1):45-55
There is an ongoing debate on whether binocular rivalry involves competition among monocular cells or binocular cells. We investigated this issue psychophysically with two specially designed test stimuli. One test stimulus contained monocular motion signals but greatly reduced binocular motion signals, while the other contained binocular motion signals but no monocular motion signals. For comparison, we also employed a normal rivalrous control containing both monocular and binocular motion signals, and a non-rivalrous flicker-noise control with neither monocular nor binocular motion signals. We found that binocular rivalry for the two test stimuli was significantly reduced compared with the normal rivalrous control, but not completely eliminated compared with the non-rivalrous control. Therefore, both monocular and binocular motion signals appear to contribute to motion rivalry, suggesting that motion rivalry must involve competition among both monocular and binocular cells.  相似文献   

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