Do you know about variable blindness? It is said that the environment has obviously undergone major changes, but it is difficult for people to perceive.
The change is so great that the stranger who asks you for directions secretly changes one, and you don't feel that the conversation can continue.
The experiment was simple, first let A randomly ask for directions, when someone held up a billboard and shouted "borrowed" to separate the two.
After that, A slipped away holding a billboard, replaced by B and left to ask, the two people looked, height, dressed, and sounded different.
Innocent passers-by are unaware and will continue to give B directions.
This experiment first appeared in 1998, and has since been reproduced on countless television programs and online videos, and only a few people can feel that something is wrong.
(Search for "Change Blindness" or "Change Blindness" to find a lot)
In the past, scientists looked for reasons for this strange phenomenon from aspects such as attention distribution.
Now, a new study published in the science sub-journal offers a whole new interpretation from the perspective of cognitive neuroscience.
It turned out that there was a problem with the underlying mechanism of the brain processing visual information.
The researchers designed a new experiment, analyzed the results and proposed:
There is a delay in the brain's processing of visual information, but it only updates the images seen in the recent period of time after an average mixture.
The refresh time is about 15 seconds.
Is the brain lazy?
In order to eliminate the effects of inattention, this experimental method no longer allows the environment to change suddenly, but uses images that change continuously.
They approached two groups of people and asked how old a young face and an old face were.
A third group of people watched a 30-second video of the face getting older and asked how much they had increased their age.
As a result, the 47 people who watched the video significantly underestimated the age change, underestimating the average age of about 5 years.
Continue to verify, turn the video upside down, and let the fourth group of people watch from old to young, and it turns out that these people also underestimate the change.
In order to make the experiment more accurate, the researchers have done more experiments to exclude other influencing factors.
For example, change the gradient of the age change of the face in the video, from gradual change to sudden change. The conclusion is that the larger the gradient of change, the less influence the participants are affected by the beginning of the video.
This further illustrates that the participants' judgment of the age of the faces is not only related to the opening image, but also to the entire video.
In addition, there are random noises to the video, changing age changes to gender changes, etc., a total of 12 sets of comparative experiments, which will not be shown here.
In summary, the study calculated based on the results of all experiments:
People don't see the latest live images, but the result of smoothing all the information in the last 15 seconds or so.
The paper's authors, Mauro Manassi and David Whitney, from UC Berkeley.
They think this brain mechanism is a kind of "laziness", or procrastination, but it has two advantages.
One is that it can save energy.
Processing each frame of visual information in real time requires the constant mobilization of a large number of visual neurons, which is too expensive.
The other is to bring stable cognition.
If the images are updated in real time, humans will feel that the world is too chaotic and unstable.
Slight changes in light and shadow and perspective will make it impossible to determine whether the object in front of them is the same as before, and it is impossible to live a normal life.
But there are also downsides
This delay and fuzzy mechanism has a positive effect in most everyday life scenarios, but it can also create problems when absolutely precise visual information is required.
Another study from the same team found that when radiologists examined X-rays, they were not only judged based on the current film, but also influenced by previous films.
The resulting error rate is about 3%-5%, which will cause misdiagnosis to patients, affect treatment and even endanger life.
I wonder if this means that it is more advantageous to entrust these tasks that require accuracy to AI without a delay mechanism?
Finally, you can test whether you will change blindness and see how long it takes to find the difference between the front and back of this picture.
Address of the paper
https://www.science.org/doi/10.1126/sciadv.abk2480
Reference Links:
[1]https://theconversation.com/everything-we-see-is-a-mash-up-of-the-brains-last-15-seconds-of-visual-information-175577
[2]https://link.springer.com/article/10.1186/s41235-021-00331-z