We suspect that the difference stems primarily from the difference in eccentricity which modulates the relative weight of the two suggested components involved in the process: contrast adaptation and neural competition. This results in a difference in the effect of contrast with eccentricity.
Another study which tested the effect of contrast on MIB [20] , compared MIB with perceptual filling-in of the type first reported by Ramachandran and Gregory [4]. In addition, they found the initial time-to-fade in MIB to be largely invariant to contrast except from the very low luminance target at about 3 sec, as compared to our moderate increase around 5 sec Figure 4a.
More significant and striking is the discrepancy between the two studies in the static mask condition. These differences are most likely due to the smaller target and the random dot mask in the Hsu et al study, which adds an additional component of perceptual filling-in. Hsu et al. This explanation cannot account for the opposite pattern of results we obtained with a static mask and MIB Figure 3b , and is inconsistent with the Bonneh et al. Given these discrepancies, the similarities between the effects of contrast in MIB and perceptual filling-in [20] cannot be used to make a strong claim about common mechanisms causing both effects.
Instead, we propose that filling-in by a surrounding pattern e. Taken together, the discrepancies between the current results and those from previous studies do not undermine our conclusions. The stimuli in the previous studies appear to have induced additional interactions beyond those processes revealed by our study.
The idea of two components involved in MIB was previously suggested by Gorea and Caetta [13] and is further supported by a detailed study of contrast detection and discrimination under invisible periods in MIB [37].
This study found both a sensitivity reduction indicative of inhibition and decisional criterion elevation indicative of an additional factor operating in MIB during invisibility [37]. In a following study, Gorea and Caetta [13] further specified these two components in terms of two gain modulation mechanisms: adaptation of the neural population responding to the target , which causes a known response-gain change over time during continuous stimulation, and transient-to-sustained inhibition of the response to the static target by the response to the moving mask , which causes a contrast-gain.
These two components, together, can cause responses to the target to fall below perceptual threshold. As discussed in the introduction, a simple implementation of this proposal implies a symmetric change of visible and invisible periods with changes in stimulus strength that alter these gains, for both MIB and Troxler fading.
Our findings well match this pattern of results for Troxler but strongly deviate from it in MIB. This deviation is not related to adaptation over time, as we obtained a similar pattern of results when discarding the initial part of inspection see Results , and thus should be explained by the dynamical properties of the proposed inhibition mechanism.
In order to produce time-to-fade or visibility period , which is almost invariant to contrast, one should assume inhibition which is proportional to contrast with a time course to reach full inhibition effect which is largely independent of contrast.
Physiological evidence for contrast-dependent inhibition exists [38]. An alternative explanation, which is indicated by the similarity of the results to other types of bi-stable phenomena is related to competition and is discussed below. Our findings link MIB and Troxler fading to two other bi-stable visual phenomena, for which parametric manipulations of the strength of the competing stimulus components produced analogous effects on the dynamics of perception: binocular rivalry BR , [28] and a rotating structure-from-motion SFM sphere [29].
The analogy can be summarized in terms of Levelt's propositions for binocular rivalry BR and the deviations from these propositions at extreme values of stimulus strength [28] , [29]. Unlike in BR, where stimulus dominance is quantified as visibility of one of the two stimuli, in MIB and Troxler we quantify the two asymmetric dominance states as target visibility and invisibility.
For MIB, the visible and invisible periods match Levelt's proposition 2: strengthening only one stimulus target contrast does not affect the duration of the corresponding percept target visible period , but shortens the dominance duration of the alternative percept target invisible period.
By contrast, Troxler fading does not match that proposition. Exactly the same deviation as in Troxler also occurs in BR, when the contrast of the other fixed-contrast image is close to detection threshold [28]. Within the target contrast range twofold increase , the mask speed does not affect the duration of the corresponding percept invisible period , but shortens the duration of the alternative percept visible period.
Again, this symmetry of the effects of target and mask strength is analogous to BR [28] and SFM [29]. Finally, the effects of mask speed and target strength on the transition rate are analogous to SFM [28] , [29]. This is true with respect to both matches and mismatches with Levelt's proposition 4: strengthening both stimuli will increase the alternation rate. In particular, when the strength of one of the two stimulus components is close to zero i.
Such common principles are often suggested e. Most authors have pointed to the similar asymmetric shapes of the distributions of the perceptual state durations in these phenomena e. Measuring the perceptual dynamics under a full parametric manipulation of the relevant stimulus parameters, like the ones performed here, is more sensitive to establish such links, and our results are consistent with those for BR and SFM.
In a detailed comparison of MIB and Troxler fading with respect to target contrast we found a lawful pattern of results with marked qualitative differences. Increasing target contrast increased doubled the rate of disappearance events in MIB, but shortened it to half in Troxler.
On the other hand, MIB and Troxler did not differ in the mean invisibility periods which decreased with contrast. We interpret the results in terms of two processes involved in perceptual suppression: contrast adaptation, which is common to both MIB and Troxler, and neuronal competition, which is dominant in MIB, as well as in other bistable phenomena such as binocular rivalry.
Performed the experiments: AC YB. Analyzed the data: YB. Browse Subject Areas? Click through the PLOS taxonomy to find articles in your field. Abstract Extended stabilization of gaze leads to disappearance of dim visual targets presented peripherally.
Methods Subjects Ten observers 5 females, ages 25—50 with normal or corrected-to-normal vision including two of the authors YSB, THD participated in the experiments. Download: PPT. Figure 1. Example of stimuli used to measure MIB for different luminance contrast levels of a peripheral Gaussian target. Procedure All experiments consisted of several trials duration: 1 min involving continuous viewing of one of the above-mentioned stimulus configurations, which remained constant throughout the trial.
Figure 2. MIB and Troxler disappearance as a function of contrast 10 observers. Figure 3. Disappearance as a function of contrast for Troxler no mask , static mask, slow mask, and fast mask 5 observers. Figure 4. Two properties related to the effect of inspection time. Invisible and visible periods vs. Relation to previous studies of MIB In a previous study of MIB [1] the percentage of time invisible was found to increase with the luminance contrast of the target.
Relation between MIB and other bi-stable visual phenomena Our findings link MIB and Troxler fading to two other bi-stable visual phenomena, for which parametric manipulations of the strength of the competing stimulus components produced analogous effects on the dynamics of perception: binocular rivalry BR , [28] and a rotating structure-from-motion SFM sphere [29].
Conclusion In a detailed comparison of MIB and Troxler fading with respect to target contrast we found a lawful pattern of results with marked qualitative differences. References 1. Nature — View Article Google Scholar 2. Nat Rev Neurosci 3: 13— View Article Google Scholar 3.
Neuron — View Article Google Scholar 4. View Article Google Scholar 5. Ophthalmologisches Bibliothek. Jena: Fromman. J Vis 6: — They found that the disappearance and appearance of stimuli can be modified with TMS pulses to the parietal cortex, an area implicated in visuospatial attention. By combining motion-induced blindness and TMS in patients with parietal cortex damage, especially those that experience visual extinction, it is possible that a therapeutic procedure could be found to alleviate symptoms.
Now you should have a good understanding of how to incorporate the elements and run the experiment, as well as how to analyze and assess the results. Subscription Required. Please recommend JoVE to your librarian. Figure 2 shows typical results from a single observer.
The moving blue crosses cause the brain to believe that the yellow discs may not really be there. But the more discs there are, the less the brain seems to trust that intuition.
So only one disc is more likely to disappear compared to two or all three. Figure 3: Percent of time stimuli are absent from awareness. Results are shown from one typical observer.
Motion-induced blindness demonstrates that the brain constructs awareness, and that it can decide what to include there or not. But why does this stimulus cause the brain to believe that the yellow discs are not actually there, deleting them from awareness?
One of the applications of this relatively new technique emerges from a theory designed to answer that question. The theory is known as the Perceptual Scotoma theory, proposed in If a piece of the retina is damaged, the observer should in principle see the consequences in their perceptual awareness.
They might see an empty space wherever in the visual field the scotoma is. They don't though. In fact, people are usually not aware they have scotomas at all.
It's like wearing very dirty glasses. Often, one only realizes the glasses are dirty when they take them off.
Why don't smudges and specs of dirt appear in perceptual awareness? Why don't scotomas as well? The answer is that the brain knows that scotomas are possible. And when it believes some stimulus is caused by a scotoma, it discounts it since it thinks it is not part of the outside world.
The way it determines that something is a scotoma is if the stimulation is invariant with respect to the rest of the outside world. In motion-induced blindness, there is a clearly rotating surface-the square made up of crosses-but the yellow discs are invariant; for some reason, they don't rotate as they should if they were on the surface.
Therefore, the brain concludes that they must not be, and instead, that they must be inside the eye, an aberration, perhaps caused by an injury. The same principle applies to dirt on someone's glasses. The brain notices that the specs of dirt move wherever the head moves, as they should, only if they are attached to the head in some way. So the brain deletes them from awareness, focusing its interests on what it thinks is in the world outside the observer.
This theory and the illusion of motion-induced blindness has made it possible for scientists to study the ways that the brain compensates and creates awareness when a scotoma occurs, when injury produces imperfections and in the human eye. Sensation and Perception. Motion-induced Blindness. To learn more about our GDPR policies click here.
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Login processing This is a sample clip. Sign in or start your free trial. Scholvinck, M. Neural correlates of motion-induced blindness in the human brain. J Cognitive Neurosci 22, — Donner, T. Retinotopic patterns of correlated fluctuations in visual cortex reflect the dynamics of spontaneous perceptual suppression. J Neurosci 33, — Tsuchiya, N. Continuous flash suppression reduces negative afterimages. Nature 8, —, Attentional influences on the dynamics of motion-induced blindness.
J Vision 9, 1—9 Motion-induced blindness and troxler fading: common and different mechanisms. PLOS One 9, e Gorea, A. Adaptation and prolonged inhibition as a main cause of motion-induced blindness.
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Atten Percept Psycho, Alais, D. Visual sensitivity underlying changes in visual consciousness. Download references. The authors thank Randolph Blake and Alex Maier for helpful comments on the manuscript.
You can also search for this author in PubMed Google Scholar. All authors contributed to the study design. Testing and data collection were performed by K. All authors approved the final version of the manuscript for submission. This work is licensed under a Creative Commons Attribution 4. Reprints and Permissions. Sci Rep 5, Download citation. Received : 28 January Accepted : 14 May Published : 03 July Anyone you share the following link with will be able to read this content:.
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