Interesting historical experiments reveal 5 little-known facts about infant vision

Out of the 5 senses (including sight, hearing, taste, smell and touch), vision is the slowest developed sense in babies.

Just a few hours after birth, a baby’s hearing is so complete that it can help them detect and turn their face in the direction of sound. Babies can distinguish between different volumes and frequencies, especially recognizing the mother’s voice.

In terms of taste, babies have long been known to prefer sweet and can perceive three additional tastes including salty, sour and bitter. Baby’s sense of touch has also developed to the point of being sensitive to touch, temperature changes, and pain.

On the olfactory side, babies recognize their mothers by the smell of their breasts and armpits. Children will also hide or turn away when unpleasant odors appear (a father smokes, for example).

However, in terms of vision alone, the development proved very limited. During the first 2 weeks, babies rarely open their eyes.

You may not know, at the time of birth every child is considered functionally blind . That’s because the cone and rod photoreceptors in our eyes are not yet connected to the brain. These cells are located in the retina that help you perceive color and light.

They are basically the same as sensor points in a camera. When not connected to the brain, the eyes of newborn babies are like a camera in the first ” unboxing ” without the battery and memory card inserted.

In 1998, American scientist Philip Kellman did a study to confirm that the vision of newborns was only 20/600.

That means a newborn baby can only see at 20 feet (60 cm) what an adult can see at 600 feet (183 m). According to the clinical definition, 20/200 is considered to be the threshold of blindness, therefore, all newborns are considered functionally blind at birth.

It is not until 6 months of age that a child’s eyesight develops to the threshold of 20/100, and by 12 months of age, a child can achieve vision as an adult.

But that does not mean that in the first year of life, a child’s vision is completely useless. Since the mid-20th century, scientists have been studying the development of babies’ vision. The first thing they discovered was that babies are very sensitive to light.

Sensitivity to light has allowed children to detect slow-moving objects in their limited field of vision, especially objects of high contrast and moderate complexity.

Interesting historical experiments reveal 5 little-known facts about infant vision
Simulation of infant visual acuity up to 6 months of age, compared with adults.

Even so, the world of an infant is not just black and white. Scientists say babies under 2 months old can already perceive colors, but they will have difficulty distinguishing some colors from each other, including white, yellow, blue and blue.

It is not until 2-3 months of age that babies can distinguish all the basic colors. And by the 4th month, your baby will be able to put together objects of the same color but with different colors into each group: blue, green, yellow and red.

It is a fact that babies are often attracted to faces. You can shake your head while playing with a baby, and it will be extremely amusing.

In 1961, an American scientist named Robert Lowell Fantz performed a visual experiment to explain this phenomenon. He cut a cover with a human face on it, another with a human face, but with eyes, nose, and ears turned upside down, and a blank card that appeared to have only simple hair.

The cards were passed back and forth in front of babies just a few minutes old to five weeks old, to see which they liked best. The results showed that the children were attracted, they kept their eyes and turned their heads to both pieces of cardboard with a normal human face and a human face with upside down facial features.

Interesting historical experiments reveal 5 little-known facts about infant vision
Children’s interest in human face drawings.

From the age of 4 days to 2 months, babies tend to be more stimulated by faces, while black and white blocks are increasingly ignored. This proves that babies just a few minutes old are already able to follow visual stimuli with their eyes and head, and they show a greater preference for things with the shape of a human face.

Why do babies have this preferential reflex? One possibility, it is an adaptive remnant of our evolutionary history. Reflexes are controlled by subcortical areas, directing infants to caregivers and promoting social interactions.

A simpler explanation is that children like to look at high-contrast patterns , with lots of sharp boundaries between light and dark areas. Human faces, even when the five senses are disturbed, respond to these conditions, making them the object of the child’s attention.

In addition, analytical experiments also show that children prefer patterns of moderate curvature and complexity. This may be because at less than 2 months of age, a baby’s vision has not yet developed enough to achieve a clear resolution of detail.

The human face also meets the requirements for resolution and curvature, while many other shapes cannot.

Interesting historical experiments reveal 5 little-known facts about infant vision
This drawing simulates what a baby under 2 months old sees.

When is the time when children begin to string together the images they see, such as guessing a partially obscured object? As in an experiment below:

The scientists had a group of 4-month-old babies take turns looking at screen A showing a long stick behind a square plate, looking so much that they got bored and didn’t even bother to react to the object.

The children were then shown between pictures C and D, to see which they were more interested in. The goal is to find out if the child perceives in figure A as one long bar behind the square, or two separate short bars.

If children recognize the object as a long stick, they will be more interested in the D (which is two short sticks), because children are always excited with completely new and unfamiliar objects, while being experimented with. get familiar and boring with the stick in figure C.

The results in the first trial with image A showed that the child was not completely biased towards the C bar or the two D bars, indicating that both images were completely new to the child.

Interesting historical experiments reveal 5 little-known facts about infant vision
Babies from birth to 2 months old cannot yet assemble the movements they see to infer a whole object when it is filled.

But when the scientists exposed the children to B first instead of A. In Figure B, the long rod was moved back and forth behind the square plate. The child seems to have recognized the synchronization in the direction of motion of the two protruding sticks, thereby inferring that it is only a single stick.

Of course, in the results of experiment 2 between C and D, the children were more interested in the two D sticks than the C stick they had previously realized.

Repeating experiments with babies 4 months old and younger, the scientists found that babies from birth to 2 months old could not yet assemble the movements they saw to deduce a whole object when it was filled. . This ability only develops when the baby is 2 months old.

But by the 3rd and 4th months of age, the baby can already perceive some of the still images.

Interesting historical experiments reveal 5 little-known facts about infant vision
Look closely at the image below, do you see a square lying on top of the black circles?

Of course, many people will find it simple, but for a 3-4 month old baby, figuring out the dashed lines of a square requires the work of the mind, not just the sight.

Above 4 months of age, babies can perceive hidden images in dynamic contexts, like the stick behind the square piece in the test above. By 8 months of age, babies may not need signs of movement to recognize that an entire stationary object is obscured.

A 12-month-old baby has developed a visual sense to the point of being able to recognize shapes drawn by a moving point of light, just as you would with a laser pen to trace a circle or square on a wall. This is what an 8-month-old or 10-month-old cannot do.

Babies are very young and can perceive movements in 3D space. For example, when you bring your fist or an object close to a 1-month-old baby’s eyes, he will have a defensive reaction of simply blinking.

Along with that, the child may also respond to this stimulus by pressing his head back to avoid the object or swinging his arm forward to knock it out. Scientists found that when a child blinks faster, it means that the baby is afraid of colliding with an object. Meanwhile, blinking slowly is simply in response to the object blocking its view.

Like a camera’s aperture, when an object gets close to a child’s eyes, it takes up more of the visual field, so the child will see less of the scene behind the object. A closer object also means that its image on the retina will be larger, compared to when the object itself is far away with a smaller image.

But can the child know that near and far objects are the same, even though their sizes on the retina are different?

Interesting historical experiments reveal 5 little-known facts about infant vision
This effect known as ” isometric perception ” or ” constant size ” is not present in infants under 3 months of age. Scientists say that only when babies reach the age of three to five months do they develop binocular vision good enough to make accurate spatial inferences.

But if combined with the perception of motion, the baby can feel isometric at 4 months. And at 6-7 months of age, the baby can begin to perceive the depth of space with a eyes without using both eyes or perceiving motion.

Isometric perception progresses very steadily during the first year of a child’s life, but it is not completely complete until the child is 10-11 years old.

Now, parents may have to worry. By 7 months when your baby starts crawling, is his spatial awareness enough to keep him from crawling off the edge of the bed or falling down the stairs? Scientists again did an experiment to answer that question:

Interesting historical experiments reveal 5 little-known facts about infant vision
Would a 7 month old baby casually crawl to the edge of the bed or the edge of the stairs?

In 1960, scientists Eleanor Gibson and Richard Walk designed a model called the cliff illusion to see if infants could perceive depth. The cliff is essentially a glass platform divided into two parts. The child is placed in the middle, on a white path.

Below the glass on the right, Gibson and Walk placed a flat checkerboard paper. Meanwhile, on the left side, they created a hole a few dozen centimeters deep plus the visual effect turned it into a wall of real depth.

Parents will take turns coaxing their children to go to the left or right glass. Gibson and Walk observed that babies aged 6-6.5 months were more likely to walk to the right. Only 10% of the children dared to go to the left side of the cliff, compared to 90% who would go to the opposite side safely.

So it is clear that once babies can crawl, they will be aware of depth and afraid of falling. Parents sometimes don’t have to worry too much about their baby crawling off the edge of the bed or the stairs, though of course it’s still a risk to watch out for.