Before we come into the world, our whole universe is our mother's womb. You'd think there'd be little to see inside; and in fact, there is, because a human fetus is in the process of forming, of acquiring eyes.
Does this mean it can't see? A few years ago, a study published in the magazine Current Biology has shown that during the third trimester of pregnancy, babies already have much more advanced visual abilities than previously thought. They see, but what do they see?
It all starts with a very blurred vision: objects, light and movement are blurred when they are presented to them. They do so, moreover, under a spectrum of gray tones. However, after two or three days, the creature will already perceive faces and, probably, expressions on those faces. That is, only of what is at a distance of no less than thirty centimetres. If the world moves further away, they will continue to see it blurred.
Despite the difficulties, it turns out that newborns are pretty good at processing faces. In 2017, researchers at Lancaster University in the UK set out to find out more about this and, to put it this way, they saw the light.
When the light goes
To begin with, they examined 39 fetuses with a gestational age between 231 and 252 days. To do this, they used non-invasive processes to assess their visual abilities. How? By shining a light through the maternal tissue.
A newborn baby needs fifty times more light than an adult to be able to see. What's more, it's only after the first month that new colors appear in its visual palette.
A newborn baby needs fifty times more light than an adult to be able to see. This is why they instinctively turn towards the most intense light sources (you can see them directing their faces towards this light, towards the brightest tones), which is what they find on their stage. Similarly, it's only after the first month, and especially from the second onwards, that new colors appear in their visual palette. They don't yet see images, but they do perceive light. Between three and four months, light perception finally improves, and babies recognize more colors.
With these basic notions, the light the researchers used consisted of three vanishing points, sometimes arranged to represent the points that balance (and form) a face, i.e. two for the eyes and one for the mouth. Occasionally, they reversed them.
New developments
To check for any movement in the babies, resulting from their gaze stimuli, they used 4D ultrasound: if the babies turned their heads, or moved their arms, or perhaps squinted their eyes, they could pick it up. It turned out that dots representing faces attracted their attention more.
According to the authors, these found preferences don't just mean new advances in notions that existed: they could mean that we develop this preference even before we're born, or in other words, that it could be an innate characteristic. Although subtle, they indicate, this attraction to facial configuration would mark a big difference in our understanding of vision development. In 2019, another team of researchers from the University of California at Berkeley discovered that in the developing eye, perhaps 3% of ganglion cells (the cells in the retina that send messages to the brain via the optic nerve) are sensitive to light.
To date, researchers have found about six different subtypes that communicate with several locations in the brain. Some talk to the suprachiasmatic nucleus to synchronize our internal clock with the day-night cycle. Others send signals to the area that makes our pupils contract in the presence of bright light. Thanks to these advances, we now also know that the fetus actively interacts with visual information in its prenatal environment: indeed, they move their heads to follow stimuli. The next step, they say, is to study whether or not they can distinguish between quantities or numbers.
Before we come into the world, our whole world is the womb. One might imagine that there is little to see inside; and in fact, this is so, because a human fetus is at this moment in the process of forming, of acquiring eyes. Does this mean it can't see? A few years ago, a study published in the journal Current Biology showed that during the third trimester of pregnancy, babies already had much more advanced visual abilities than previously thought. They see, but what do they see?
