Flash suppression

<h2 id="relationship-with-binocular-rivalry">Relationship with binocular rivalry</h2>

Flash suppression occurs due to the conflict between the inputs to the two eyes. When this conflict is sustained without any abrupt events, binocular rivalry occurs. In both flash suppression and binocular rivalry, perceptual conflict between the two eyes is required for the perceptual effect. If two similar images are used, fusion of the two images is experienced, rather than flash suppression or binocular rivalry. Despite some similarities in perceptual consequences, the neuronal mechanisms responsible for the two illusions can be different. For example, the strength (depth) of flash suppression seems much stronger than that of binocular rivalry. Comparative studies of the two methods are needed.
Flash suppression has certain methodological advantages over binocular rivalry as a tool for probing conscious vision. Whereas the percept during binocular rivalry alternates <a href="/facts/Stochastically/uMbgL94r">stochastically</a>, the percept during flash suppression is precisely controlled in time.
Although flash suppression allows one to present an image to someone without his or her seeing it consciously, it requires a to-be-erased image to be presented for a fraction of second before introduction of a new image. This requirement limits the usage of flash suppression for the study of nonconscious visual processing.

<h2 id="continuous-flash-suppression">Continuous flash suppression</h2>
Main article: <a href="/facts/Continuous_flash_suppression/PgrXX7tj">Continuous flash suppression</a>
A powerful variant of flash suppression is continuous flash suppression, originally reported by Nao Tsuchiya and Christof Koch (2004)<a class="footnote-ref" id="fnref:7" href="#fn:7">7</a> and Fang and He (2005).<a class="footnote-ref" id="fnref:8" href="#fn:8">8</a> Here a small, fixed image in the first eye—say a gray-scale fearful face—is completely suppressed by a stream of constantly changing images flashed into the second eye (say a series of colorful Mondrian-scenes replaced every 0.1 sec by a new Mondrian pattern). This suppression can last for minutes, a remarkable testament to the fact that humans often do not see what is directly in front of their eyes.
Continuous flash suppression is a useful method for psychologists and neuroscientists interested in studying the mechanisms of conscious and nonconscious visual processing. Whereas other visual illusions that render otherwise <a href="/facts/Salience_(neuroscience)/tnN4Nqcp">salient</a> images invisible have their own shortcomings and advantages,<a class="footnote-ref" id="fnref:9" href="#fn:9">9</a> continuous flash suppression has a number of advantages for wiping images from conscious vision. It can erase an image presented at the <a href="/facts/Fovea_centralis/cCqjWzTj">fovea</a> (which usually is much more resistant to perceptual suppression, unlike, for example, <a href="/facts/Visual_crowding/QoU4BxgI">crowding</a>), in every trial (unlike <a href="/facts/Binocular_rivalry/XrVeDbP9">binocular rivalry</a>), for a longer duration (>1 sec, unlike <a href="/facts/Backward_masking/H9JYzqfo">backward masking</a>), with an excellent control of timing (unlike binocular rivalry). It has been widely exploited to tackle the scope and limits of unconscious processing.<a class="footnote-ref" id="fnref:10" href="#fn:10">10</a>

<h2 id="generalized-flash-suppression">Generalized flash suppression</h2>
The differences between flash suppression and <a href="/facts/Binocular_rivalry/XrVeDbP9">binocular rivalry</a> have been further emphasized by the finding that stimulus conflict between the two eyes is not a requirement to achieve visual suppression. The novel paradigm of generalized flash suppression (GFS) reported by Wilke, Logothetis and Leopold in 2003 demonstrates that any visual stimulus can be rendered invisible when presented outside the <a href="/facts/Fovea_centralis/cCqjWzTj">fovea</a> for a certain amount of time, followed by the addition of a distracting second stimulus in its vicinity.<a class="footnote-ref" id="fnref:11" href="#fn:11">11</a>
This effect is strongest when the two stimuli are presented to (different regions in) opposite eyes, which suggests that it is somewhat related to binocular rivalry. At the same time, GFS shares similarities to <a href="/facts/Troxler%2527s_fading/UvDItNUa">Troxler's fading</a> and <a href="/facts/Motion_induced_blindness/cQVzgJBv">motion induced blindness</a>.
A recent study on the neuronal basis of GFS demonstrated that <a href="/facts/Neuronal/G7CyTVdH">neuronal</a> activity in early <a href="/facts/Visual_cortex/qmF8F5Sb">visual cortex</a> was untouched by the perceptual effect, whereas <a href="/facts/Neurons/G7CyTVdH">neurons</a> in higher areas altered their activity pattern during the <a href="/facts/Illusion/Wp52FHKV">illusion</a>.<a class="footnote-ref" id="fnref:12" href="#fn:12">12</a> Authors report that the disappearance of the stimulus triggered changes in the <a href="/facts/Local_field_potential/uAPJRyz9">local field potentials</a> of all these areas, suggesting that the <a href="/facts/Perception/xLK0n2q4">perception</a> during flash suppression is reflected in large parts of the brain.

Reviews

<ul><li><a href="http://zhichenglin.googlepages.com/seeingtheinvisible.pdf">Lin, Z., He, S., Seeing the invisible: The scope and limits of unconscious processing in binocular rivalry, Progress in Neurobiology (2007)</a>, [permanent dead link] <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1016%2Fj.pneurobio.2008.09.002">10.1016/j.pneurobio.2008.09.002</a>.</li></ul>
Flash suppression 

<ul><li>Sheinberg, DL; <a href="/facts/Nikos_Logothetis/TSpTE8om">Logothetis, NK</a> (1 April 1997). <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC20383">"The role of temporal cortical areas in perceptual organization"</a>. Proceedings of the National Academy of Sciences of the United States of America. 94 (7): 3408–13. <a href="/facts/Bibcode_(identifier)/9HtdQSGB">Bibcode</a>:<a href="https://ui.adsabs.harvard.edu/abs/1997PNAS...94.3408S">1997PNAS...94.3408S</a>. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1073%2Fpnas.94.7.3408">10.1073/pnas.94.7.3408</a>. <a href="/facts/PMC_(identifier)/dX1zMt71">PMC</a> <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC20383">20383</a>. <a href="/facts/PMID_(identifier)/JlHAvMHt">PMID</a> <a href="https://pubmed.ncbi.nlm.nih.gov/9096407">9096407</a>.</li>
<li>Tsuchiya, N; <a href="/facts/Christof_Koch/XvABx1QX">Koch, C</a>; Gilroy, LA; Blake, R (21 September 2006). <a href="https://doi.org/10.1167%2F6.10.6">"Depth of interocular suppression associated with continuous flash suppression, flash suppression, and binocular rivalry"</a>. Journal of Vision. 6 (10): 1068–78. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1167%2F6.10.6">10.1167/6.10.6</a>. <a href="/facts/PMID_(identifier)/JlHAvMHt">PMID</a> <a href="https://pubmed.ncbi.nlm.nih.gov/17132078">17132078</a>.</li></ul>
Continuous Flash Suppression

<ul><li>Tsuchiya, N., and Koch, C. (2004) Continuous flash suppression. Vision Sciences Society, 4th annual meeting. Sarasota, FL.</li>
<li>Jiang, Y., et al. (2006) A gender- and sexual orientation-dependent spatial attentional effect of invisible images. Proc Natl Acad Sci U S A 103, 17048-17052</li>
<li>Jiang, Y., and He, S. (2006) Cortical Responses to Invisible Faces: Dissociating Subsystems for Facial-Information Processing. Curr Biol 16, 2023-2029</li>
<li>Kanai, R., et al. (2006) The scope and limits of top-down attention in unconscious visual processing. Curr Biol</li></ul>
<h2 id="external-links">External links</h2>
<ul><li><a href="http://www.scholarpedia.org/article/Flash_suppression">Flash suppression</a> at <a href="/facts/Scholarpedia/h2r7IY7J">Scholarpedia</a>.</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1">McDougall 1901, p. 598 <a href="#fnref:1" class="footnote-back-ref">↩</a></li>
<li id="fn:2">Lansing 1964 <a href="#fnref:2" class="footnote-back-ref">↩</a></li>
<li id="fn:3">J.M. Wolfe (1984) Reversing ocular dominance and suppression in a single flash. Vision Res 24, 471-478 <a href="#fnref:3" class="footnote-back-ref">↩</a></li>
<li id="fn:4">Koch, C. (2004) The Quest for Consciousness: A Neurobiological Approach, Roberts, Englewood, Colorado <a href="/wiki/Christof_Koch" target="_blank">/wiki/Christof_Koch</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></li>
<li id="fn:5">Logothetis, N.K. (1998) Single units and conscious vision. Philos Trans R Soc Lond B Biol Sci 353, 1801-1818 <a href="/wiki/Nikos_Logothetis" target="_blank">/wiki/Nikos_Logothetis</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></li>
<li id="fn:6">Kreiman, G., et al. (2002) Single-neuron correlates of subjective vision in the human medial temporal lobe. Proc Natl Acad Sci USA 99, 8378-8383 <a href="#fnref:6" class="footnote-back-ref">↩</a></li>
<li id="fn:7">Tsuchiya, N., & Koch, C. (2005). Continuous flash suppression reduces negative afterimages. Nature neuroscience, 8(8), 1096-1101. <a href="#fnref:7" class="footnote-back-ref">↩</a></li>
<li id="fn:8">Fang F, He S. Cortical responses to invisible objects in the human dorsal and ventral pathways. Nat Neurosci. 2005;8:1380–1385 <a href="#fnref:8" class="footnote-back-ref">↩</a></li>
<li id="fn:9">Kim, C.Y., and Blake, R. (2005) Psychophysical magic: rendering the visible 'invisible'. Trends Cogn Sci 9, 381-388 <a href="#fnref:9" class="footnote-back-ref">↩</a></li>
<li id="fn:10">Sklar, A. Y., Levy, N., Goldstein, A., Mandel, R., Maril, A., & Hassin, R. R. (2012). Reading and doing arithmetic nonconsciously. PNAS, 109(48), 19614-19619. <a href="#fnref:10" class="footnote-back-ref">↩</a></li>
<li id="fn:11">Wilke, M., et al. (2003) Generalized flash suppression of salient visual targets. Neuron 39, 1043-1052 <a href="#fnref:11" class="footnote-back-ref">↩</a></li>
<li id="fn:12">Wilke, M., et al. (2006) Local field potential reflects perceptual suppression in monkey visual cortex. Proc Natl Acad Sci U S A 103, 17507-17512 <a href="#fnref:12" class="footnote-back-ref">↩</a></li>
</ol>

Flash suppression open-in-new

Flash suppression