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As soon as we open our eyes, the 100 million jackpot in the dream disappears... Such a scene seems to be happening every day, but why do we wait until we wake up to find that the dream is not reality?
An exploration of brain science spanning more than a hundred years found that imagination and vision are originally completed by the same area of the brain, but the intensity of neural activity is different.
The intensity of this neural activity is between imagination and vision. There is a certain threshold, and our brains use it to distinguish between the two.
When the relevant neural activity reaches this threshold, our brains perceive the scene as real.
And this threshold is not static, which explains why we can easily distinguish between imagination and reality when we are awake.
And when we enter a dream, the imagined scene may be considered real by our brain.
The author of the paper, Nadine Dijkstra, expressed the hope that this research will inspire more explorations about human imagination and create value in fields such as medicine.
Unknown for hundreds of years
About the connection between imagination and vision, scientists have put forward conjectures more than a hundred years ago.
This hypothesis is known as the "Page Effect" and was discovered by psychologist Cheves West Perky in 1910.
Perky took a group of subjects and asked them to face a wall and imagine some objects in their minds.
Perky then projected pictures of these objects onto the wall, but so faintly that they could barely be seen. And ask the subjects if they "see" it.
As a result, all the subjects answered no without exception, and they all believed that the pictures they saw were imagined by themselves.
△ Perky's thesis summary
Although the subjects said they didn't see it, the pictures were literally projected onto the wall.
According to Perky, we consider something imaginary when our perception of it matches our previous imagination.
Perky's theory can be said to be in line with the experimental results, but in scientific research, the repeatability of experiments is also very important.
For more than a hundred years, researchers have been repeating Perky's experiment, but the results are not satisfactory.
I don't know if it's because of the design of the experiment, but the subjects figured out the "intention of the questioner" when they saw the content of the experiment.
As a result, these subjects always changed their answers intentionally or unintentionally, as if trying to cater to the experimenter's ideas.
Neuroimaging makes lies 'reveal'
The human mouth may lie, but the brain activity does not.
Now, neuroimaging technology is like a "demon mirror", in front of which lies are revealed every minute.
So, Dijkstra's team used neuroimaging techniques to observe the brain activity of the subjects during the experiment.
Now, the subjects could no longer play tricks.
At the same time, to be sure, Dijkstra did not give these subjects the opportunity to change their answers at all.
Dijkstra's team proposed three hypotheses, depending on the degree of association between imagination and vision.
The first is that the two have nothing to do with each other, the second is the aforementioned "Page effect", and the third simply thinks that the two are the same thing.
Obviously, these three hypotheses are mutually incompatible, and only one experiment is needed to verify them all.
Similar to Perky's experiment, Dijkstra also had subjects meditate against a wall.
The difference is that what they are facing is no longer a bare wall with distracting information projected onto it.
A total of ten Dijkstra tests are performed, of which the first nine are the same.
But on the last occasion, Dijkstra's team surreptitiously included pictures of items in the noise.
It's just that the team has played tricks here, and the pictures added may not necessarily be what the subjects are thinking about.
In addition to being asked whether they "seeed" what they imagined, subjects were also asked how clearly they imagined.
The problem of lying is solved, but how to judge which hypothesis is true based on the experimental results?
The researchers built predictive models of the three hypotheses before analyzing actual test data.
As mentioned earlier, the pictures included in the final trial were not necessarily the ones in the subjects' minds.
So the team made predictions about how the subjects would respond, both when the picture matched the image and when it didn't.
In the disassociation hypothesis, vision is not affected by imagination, so whether or not the picture matches their imagination, the probability of judging it to be true should be the same.
Under the Page effect hypothesis, when the picture matches their imagination, it is easy to be regarded as imagination.
In the fully mixed hypothetical situation, people are more likely to believe that the scene in their mind is real, and the clearer the imagination, the easier it is to make a judgment that it feels true.
The picture below is an intuitive reflection of the above expected results, where the difference in color indicates whether the picture the subject saw is consistent with the imagined object, and the true or false indicates the content of the subject's answer.
In the actual test, the probability that the subjects believed that the image in their mind was the real image was very high.
Even if the content in the image is not what they imagined at all, as long as the picture in their minds is clear enough, they will think that they "see" the imagined item.
It is obvious which hypothesis is more suitable for such a result, and the third hybrid theory has won the final victory.
Simultaneous monitoring of brain activity also confirmed this idea.
When imagining and actually seeing an object, activity in the anterior insula, supplementary premotor area, and right prefrontal cortex overlapped.
The results of decoding analysis also showed that imagination and vision are encoded in the same way.
The active areas of the brain are all the same, can it be the same thing?
But this brings up a new question: If imagination and vision are the same thing in the brain, why can we tell the difference?
Although the principle is the same, the level of neural activity in the brain is different when performing the two activities.
During real vision, the relevant brain regions were more active than imagined.
Statistical results show that there is a certain threshold of neural activity, and signals exceeding this threshold will be recognized by the brain as real vision.
By revealing the link between imagination and vision, we may be able to induce imagination and somehow enhance neural activity to build visual cues.
At that time, there may be some kind of equipment that implants the real world into people's brains with imagination as a carrier, allowing the blind to "see" the colorful world again.
Or, through the monitoring of relevant signals, it is possible to predict the onset time of schizophrenic patients, so as to prepare countermeasures in advance...
Paper address:
https://www.nature.com/articles/s41467-023-37322-1
Reference link:
https://www.quantamagazine.org/is-it-real-or-imagined-how-your-brain -tells-the-difference-20230524/