The authors of the paper, published in the Journal of Vision, described the phenomenon of visual processing failure. It occurs if more and more visual signals begin to arrive at the neurons that process images at too high a speed. Because of this, a "congestion" occurs, the neurons cannot cope with the flow, and some images begin to "fall out" before reaching the level of consciousness.
The team found evidence that a bottleneck can occur in neurons in the pathway that signals from visual stimulation take. This neural pathway begins in the visual cortex, located at the back of the brain, and travels forward, rapidly processing visual signals up to the frontal cortex. This path then gives "feedback", again sending signals back to the areas in which the primary processing took place. According to the test results, it is with feedback that a failure occurs. This stage is necessary for the result of the brain's processing of the image to reach the consciousness of the participants in the experiment, scientists say.
“Previous research has shown that humans are quite weak at tracking attention objects that appear close to each other in time, although the human brain can process up to 70 images per second. Our research shows a specific limitation of the visual system and explains why our consciousness cannot keep at this level. When someone tells you that he did not see something that was happening in a chaotic situation, then he may have seen, but he did not know that he did it,”explains senior study author, neuroscientist Maximilian Riesenhuber, professor of neuroscience at Georgetown University Medical Center.
The authors conducted a series of experiments. The subjects were shown 1200 images, divided into two groups. The target group of the images showed animals, and the distraction showed landscapes. Participants were presented with images at 12 pictures per second, and they had to tell how many pictures depicted animals and name these animals. In the series, they could not be at all, or there could be one animal, or two.
In the second part of the experiments, there were two such streams, on two screens simultaneously. In the process, the wave activity of the brain was recorded from people using EEG. It turns out that a glitch in visual processing occurs when the back of the brain is stimulated by a second image before the feedback and feedback loop is complete for successful awareness of the first image.
Examples of targeted and distracting images, as well as brain activity in response to these images / Martin, Cox et al., Journal of Vision.
The researchers note that the work shows the existing limitations in the processing of visual stimuli by the brain. This data can help design a variety of training programs, including areas that require decision-making in difficult conditions.
“In addition to introducing a theory that explains the root cause of lack of awareness, our research also shows how to avoid neuronal signal failure and increase awareness. When we experimentally reduced the interference between the feed and feedback parts of the two stimuli, we observed an improvement in the detection and categorization characteristics. These results are exciting because they could lead to new methods of accelerating cognitive processing and learning in humans,”explains lead study author Jacob J. Martin.
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