Whether you're concerned about basketball or not, you've got to hear the name Kobe Bryant. He is the imprint of a generation of youth, a man who has scored 81 points in a single game in the NBA, a man who still insists on playing free throws after a ruptured Achilles tendon, a man who is desperate for victory. The "mamba spirit" he passed on will never retreat, never give up, never escape, endure humiliation and burden, create miracles in difficulties, show vividly, and also inspire countless people's enthusiasm! However, the envy of talent, the plane crash took away Kobe, which also makes many people who love sports remember infinitely. If you can make your "horizon" reproduce Kobe's face, can you believe it? So let's give it a try.
The picture below (Figure 1) looks mediocre at first glance, but all you have to do is stare at the four white dots on your nose and stay on it for 10 seconds without blinking, then quickly stare at the white background wall and blink continuously, and you will find an unexpected surprise - Kobe's face appears! I believe many people will have questions, what is going on? Is there a problem with the eyes? Or is there something wrong with the brain? In fact, there is no problem with both, the problem is in visual persistence (also known as the "afterglow effect").
Figure 1 Experimental image (Source: Twitter)
The brain refreshes visually with a 15-second delay
On January 14, 2022, a research team of psychology and neuroscience at the University of California, Burnley, published an article titled "Illusion of visual stability through active perceptual serial dependence" at Science Advances, which studied the underlying mechanism of the brain processing visual information from the perspective of cognitive neuroscience and found that the brain has a delay in processing visual information. It will average the images it has seen in the last period of time before updating it once, and the update time is about 15 seconds (Figure 2).
Figure 2 Research results (Source: Science Advances)
The study recruited 70 participants, divided into three groups, to watch young, elderly, and gradually aging 30-second videos of women and answer the age changes in the people in the photos. As a result, the 47 people who watched the video significantly underestimated the age change, underestimating the average age of about 5 years. In addition, the researchers conducted 12 sets of comparative experiments such as adding random noise to the video and replacing the age change with the gender change, and found that the participants' judgment of the age of the character's face was not only related to the opening image, but also affected by the entire video. Finally, based on all the experimental calculations, the researchers learned that the latest image people saw was the result of smoothing all the information in the last 15 seconds or so, not a real-time image.
Researchers Mauro Manassi and David Whitney say, "This mechanism of the brain is a 'lazy' behavior, but there are two benefits. One is to save energy, because real-time processing of each frame of visual information requires the constant mobilization of a large number of visual neurons, which consumes too much; the other is to bring stable cognition, if the image is updated in real time, humans will feel that the world is too chaotic and unstable. There are also drawbacks, this delay and blur mechanism has a positive effect in most everyday life scenarios, but it also creates problems when absolutely accurate visual information is required. ”
What are the deep causes of the phenomenon of human visual persistence?
Perception is the basis of human intelligent activity, and in daily life and work, the human sensory organs are responsible for obtaining information from their surroundings and guiding their actions. The relationship between human cognition and organs is taste 1%, touch 1.15%, smell 3.15%, hearing 11%, and vision 83%. From a memory perspective, people can remember 10% of what they read, 20% of what they hear, and 30% of what they see. It can be seen that vision is particularly important for human beings to obtain external information.
Regarding the causes of visual delay, the Department of Neurobiology at UCLA School of Medicine published a paper in Nature Reviews Neuroscience titled "Through the Eye, Slowly; Delays and localization errors in the visual system" article explains in detail (Figure 3).
Figure 3 Research results (Source: Nature Reviews Neuroscience)
The study's smooth tracking motion test showed that when the motion target T is smoothly tracked, the physical signal of T hits the retina at the time of tn-x, but the signal does not reach the brain until 40 milliseconds later, after which the brain processes the signal, at which point the eye has moved to capture the next frame of information, resulting in an error in the positioning of the moving object in time and space (Figure 4).
Figure 4 Effect of visual delay on smooth tracking (Source: Nature Reviews Neuroscience)
Human vision is a complex system of astonishing expressiveness, but one of its biggest drawbacks is the system's hysteresis response characteristics, which is also one of the temporal properties of the visual system [1]. Due to the presence of hysteresis characteristics, phenomena such as blurring and mispositioning of moving objects are seen. When an object appears in front of an observer, it takes a while to react to it, that is to say, when a visual stimulus is input into the visual system, the visual system needs to go through a response time before the person can feel the stimulus. This property leads to the fact that the object seen is actually an object at a certain time before, which is the hysteresis of the visual system.
Visual persistence makes humans have delays in judging some things, such as crossing the road, seeing an oncoming car, about to crash, although we have reacted quickly, but still can not avoid. People tend to show that the eyes see, but the brain doesn't have time to process and send instructions to the body to respond. Visual persistence also has a beneficial impact on us, for example, if there is no visual persistence, then you will not be able to enjoy the excitement of the movie.
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[2] Schlag J, Schlag-Rey M. Through the eye, slowly: delays and localization errors in the visual system. Nat Rev Neurosci. 2002 Mar;3(3):191-215. doi: 10.1038/nrn750. PMID: 11994751.
[3] Donner K. Temporal vision: measures, mechanisms and meaning. J Exp Biol. 2021 Jul15;224(15):jeb222679. doi: 10.1242/jeb.222679. Epub 2021 Jul 30. PMID:34328511; PMCID: PMC8353166.
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