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<div data-thumb = "https://3c1703fe8d.site.internapcdn.net/newman/csz/news/tmb/2019/5ce3d5071819f.jpg" data-src = "https://3c1703fe8d.site.internapcdn.net/ newman / gfx / news / 2019 / 5ce3d5071819e.jpg "data-sub-html =" Two of these images flashed briefly on the screen during visual perception tests performed by researchers at the University of Tokyo. They would seem unpredictable once the volunteers were pushed The viewers had to identify the intensity of the light (white or black color) and the orientation of the image (diagonal lines left or right). : CC-BY-ND Nakayama and Motoyoshi 2019, originally published in the Journal of Neuroscience">

The rhythmic waves of brain activity cause people to see or not complex images that flash before our eyes. An image can become virtually invisible if it blinks in front of our eyes at the same time as a low point of these brain waves. We can reset the rhythm of brain waves with a simple voluntary action, such as choosing to press a button.

The new findings come from experts who use optical illusions to understand human vision. Human sight involves activity both in the eyes and in the brain. Optical illusions are formed by playing tricks on any part of our complex visual system.

"This is the first record of rhythmic brain activity used to achieve an integrated visual perception," said Associate Professor Isamu Motoyoshi of the University of Tokyo and co-author of the recent article in research.

Recurring rhythms of attention and perception

Previous research has shown that attention fluctuates six to eight times per second (6 to 8 hertz), a rate that researchers call theta rhythms.

The recent investigation began when Motoyoshi and his colleagues were studying the illusion of Gabor's pattern, in which a fluid-moving circle appears to cross the screen.

Viewers have seen the jumps at a steady pace, regardless of the actual speed of the illusion. The pace of jumps in the optical illusion was remarkably similar to the theta rhythm of brain waves related to attention.

data-src = "https://3c1703fe8d.site.internapcdn.net/" newman / gfx / news / 2019 / 5ce3d526e07fc.jpg "data-sub-html =" The brain wave high points and the correct responses occur at similar times.The brain waves of the theta rhythm of the participants were measured by EEG ( conceptually illustrated with orange lines) Volunteers were more likely to correctly report (black lines) which image they had seen if the image was displayed together with a peak of the brain wave of their attention. -BY-ND Nakayama and Motoyoshi 2019, originally published in The Journal of Neuroscience">

"This has led us to want to study in more detail the rhythms of attention and visual perception," said Motoyoshi.

Link form and color in conscious perception

In their recent experiments, the researchers asked participants to press a button to begin each test whenever they felt ready. Then, after an unpredictable wait time, two images flashed quickly on a computer screen, one after the other. Participants then reported what images they had seen.

"These tests are considered high cognitive tasks.You must identify both the intensity of the light – white or black color – and the orientation of the image – the left diagonal lines or right, "said Ryohei Nakayama, Ph.D., previously planned. researcher in Motoyoshi's laboratory and currently a researcher at the University of Sydney, Australia.

You can not see what you're not paying attention

The wait time between pressing the button and the image flash was between 50 and 800 milliseconds. In this time, the brain waves of the theta rhythm can fluctuate four to seven times.

Participants were much more likely to correctly report the images they had seen along with a highlight of their attentive brainwaves, measured by EEG (electroencephalogram). The opposite was also true: participants were more likely to give an incorrect answer when images were displayed at the same time as a low point of their brain wave.

Theoretically, an image could become functionally invisible if it always flashed in time with the low points of brain waves of the theta rhythm.

"Under certain conditions, one must be careful to achieve a unified perception.It is classic history," Motoyoshi said.

"But it is unlikely that a specific region of the brain will attract attention.On the contrary, we think the new story is that periodic waves of brain activity are needed for both the visual perception and for attention, "he continued.

Motoyoshi and Nakayama hope that their ongoing research on visual perception will continue to reveal the complexities of consciousness.