To see well, you must first see poorly.

In a room of Prakash ProjectIn Delhi, a doctor removes the blindfold from an 11-year-old boy and he begins to see the world for the first time. This little 'miracle' has been repeated in more than 500 children since the initiative was launched in India in 2005, led by Pawan Sinha, Professor of Neuroscience at the Massachusetts Institute of Technology (MIT). A project that has both a humanitarian aspect and a scientific part, because it is a very valuable source of information to know how these children see after they have regained their sight and what differences there are from the rest.

In a work published Thursday in the magazine SciencePawan Sinha's team reveals a new and surprising result: after conducting several tests, they found that children who regain their vision have more difficulty detecting objects when the images are in black and white, as if the recovery of their eyesight, with its full color palette, was a disadvantage when it came to recognizing reality.

“The experiment was very simple,” he says. Lucas Vogelsang, one of the three main authors of the study, told “After surgery, these children were shown a series of everyday objects in shades of gray and asked to identify them. And then the same thing was done with color images.” What they saw was children under control, with vision normalThere were hardly any differences in accuracy between some images and others, but for the children in the Prakash project, the recognition rate dropped significantly when the color was removed.

To see well, you must first see poorly.

This result leads researchers to propose a new hypothesis: that in order to see well and to configure our visual system correctly, it is important to start seeing poorly, as happens with babies, who go from less to more, both in terms of concerns color vision and visual acuity. Or in other words: seeing everything well can work against our perception, because it is a system that has to be configured little by little. “Although good color vision seems intuitively desirable from the outset, we hypothesize that immediate immersion of Prakash children in colorful images may actually be harmful,” the authors write.

As a newborn, the child with normal vision is in a sense deprived of color vision, and that turns out to be an advantage.

Sidney Diamond
MIT neurologist and co-author of the study

Pawan Sinha and his team believe that the sudden acquisition of a complete picture of the children of the Prakash project – which means light in Sanskrit – can cause an abnormally strong dependence on color signals, an extreme that they also confirmed using a computer model of vision. “In contrast, for people with normal vision, early experience with gradient color input can be helpful by creating representations that emphasize luminance rather than chromatic cues, thus creating an implicit resistance to color removal.” That is, the brain is trained to use light contrast to recognize shapes. And then when the color arrives, it is no longer as relevant to this identification.

“As a newborn, the child with normal vision is in a sense deprived of color vision, and that turns out to be an advantage,” he says. Sidney Diamond, a retired MIT neurologist who participated in the study. The human brain has more plasticity at a young age and can easily learn to identify objects based solely on their brightness, he says. And while it may seem counterintuitive, that scarcity of information about color can be beneficial, as children learn to identify objects based on sparse information, something Prakash's children don't experience.

See it in black and white

“The main question that led to this research is why we are so good at recognizing objects and faces in old black-and-white photos or films, when we vividly perceive colors in our everyday experience,” Vogelsang reveals. “We wondered what the basis of this ability might be and we got an answer by studying these children in India who were born blind and underwent surgery for their blindness.”

Vogelsang expects that with this new data they will be able to develop vision rehabilitation systems for these Indian children, gradually giving them color, which could improve their perception even further. He also reports that in other tests with patients from this project who have undergone cataract surgery, they have observed that limitations in early sensory information can also benefit other perceptual aspects, such as visual acuity, and that this hypothesis could be extended to other aspects of development. , such as language acquisition. “When we are born, our vision is very blurry and this improves over time,” he explains. “What we're proposing is that if we start seeing the world this way, we can later focus on the overall scene rather than on small details like the outline of the face.”

'Sequential' senses

Pascal Mamassian, director of the Laboratory for Perceptual Studies at the CNRS, believes that this study illustrates the benefits of sequentially developing the senses and provides new robust learning strategies for artificial neural networks. “Future studies examining the importance of sensory maturation at multiple stages are likely to provide new insights into many other perceptual phenomena,” he writes in an article. analysis article simultaneously published in Science. Mamassian also reminds us that the idea that perceptual systems take time to develop is not new. “Seventy years ago, the psychologist Jean Piaget emphasized that visual perception is exceptionally impoverished at birth and takes months or even years to reach full maturation,” he writes. “Some perceptual abilities even seem to develop very late.”

Luis Martinez Otero, a neuroscientist and expert on the visual system at the Alicante Institute of Neurosciences (CSIC-UMH), considers this work as another major contribution to the science of the Prakash project, which has produced some of the most has questioned established concepts among neuroscientists. images. According to him, with this new experiment they shed light on questions such as why the development of the visual system takes so long and, above all, how this system manages to distinguish and give meaning to the constant flow of information and its various features or characteristics . properties that are simultaneously present in a visual scene.

The ability to resolve different aspects of a scene, such as color or movement, is not developed simultaneously, but sequentially. And there's a reason for that

Luis Martinez Otero
Vision expert at the Alicante Neuroscience Institute (CSIC-UMH)

For Martínez Otero, the answer these researchers get is fascinating for its simplicity. “The ability to resolve different aspects of a scene, such as color or movement, is not developed simultaneously, but sequentially,” he explains. “And there's a reason for that. This means they don't compete when it comes to setting up and optimizing the mechanisms needed to recognize and interact with the different elements and objects in the world.” For this reason, it is believed that knowing these aspects better will help a lot in designing better visual rehabilitation strategies and more efficient object recognition algorithms in artificial vision, as already noted in the article.

Look without the 'crutches' of color

The Spanish neuroscientist Susana Martinez Conde, a researcher at the State University of New York and a world-renowned vision expert, finds this work very interesting. “What I find fascinating is the fact that color information is so important to these people after they regain their sight. First of all, it is something unexpected and certainly surprising,” he says. According to him, what we see here is that “these children who regain their sight depend on color to perceive the shape of objects, while those of us who have gradually learned to see have a stool that we don't need,” he explains. He also believes that the fact that some of these children do not have a total lack of vision, but rather perceive shadows and certain colors in a dangerous way, may have played a role in this result.

I find it fascinating that color information is so important to these people after they regain their sight. It's unexpected and certainly surprising

Susana Martinez Conde
Researcher at the State University of New York and vision expert

In the same sense it is manifested Luis Gomez Robledo, an expert in the psychophysics of vision from the University of Granada (UGR), who recalls that the authors work with people who do not have complete blindness as such, but whose vision is very blurred. “They compare children who have blurred vision all their lives with children who have always seen clearly,” he explains, “and what they show is that those who have blurred vision all their lives, learned paying attention to details such as color.” As for color, he adds, the result is interesting, although he points out that “there is a lot of variation among observers.”

For the neuroscientist and popularizer Xurxo Mariño This is a study that shows how clinical works field It can help understand the most fundamental mechanisms of nervous system functioning. “With the peculiarity that here we do not start from the laboratory, but the process is the other way around: on the basis of a human and social problem (girls and boys with congenital blindness in India), mechanisms are discovered on the process of vision development,” he says “And the results are very interesting: it turns out that it is better to start seeing little by little than to open your eyes at birth with a perfectly formed retina.”

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