What Can Babies See in the Womb?

A human fetus doesn't develop retinas until around gestational week 28. Learn how researchers have tried to figure out what babies can see in the few remaining weeks before they're born in this episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain stuff. From how stuff works, Hey, brain stuff,
Lauren Vogel bomb Here, it might seem like fetuses are
up to all that much other than growing in the cozy,
warm environment that is their mother's womb. And I mean
growing from a bundle of cells into an independently living,
breathing human being is a big enough job. However, research

(00:22):
published in the Journal of Current Biology shows that third
trimester fetuses have vision capabilities much more advanced than previously thought,
and further, they can choose what they want to look at.
Researchers from Lancaster University in the United Kingdom were keen
on expanding the understanding of fetal site capabilities. We spoke
via email with Vincent Read, the lead researcher and a

(00:43):
professor of psychology. He said, we've been able to explore
the use of all the fetal senses except for vision
up until now. There's a lot that we know about
newborn babies and their vision, but almost nothing with fetuses.
Just before they're born. The newborn is very good at
processing faces and prefers to look it faces over any
other shape. So it was logical to explore the development
of this preference before birth. The researchers examined a total

(01:07):
of thirty nine fetuses. There would have been more, but
some of the babies were in deep sleep because they
apparently missed the memo about participating in a research study,
while other tests experienced poor image quality. The fetuses ranged
in gestational age from two hundred and thirty one to
two hundred and fifty two days that's about thirty three
to thirty six weeks. Site is the final sense to
develop inside the womb, with eyes staying closed until around

(01:30):
just stational week twenty eight. This is because fetal retinas
aren't developed until that point. Oh and all of the
babies were singletons. No twins or multiple pregnancies were studied.
Because the safety and comfort of the fetal participants and
their mothers was of utmost importance, the researchers designed noninvasive
attempts to assess the baby's visual capabilities. To do so,

(01:51):
the scientists shown lights through the maternal tissue. Read explained
the light consisted of three dots. When these are arranged
to represent two the eyes and one for the mouth.
Newborn babies prefer to look at them more than anything else,
so we didn't show fetuses of face, but an image
that was face like. The researchers used for the ultrasound

(02:11):
to measure if and how much the fetuses turned their
heads in response to the stimuli. They also showed the
same three dot pattern, but inverted so it didn't resemble
a face in structure to the fetuses. As it turns out,
non facelike dots weren't as appealing. Read noted that newborns
don't find these configurations very interesting either. Although subtle attraction

(02:32):
to the face like configuration of three dots makes a
big difference in what we understand about developing site, Reid said,
it means we have this preference even before we're born.
It's either due to being innate or due to experiences
prior to birth. Another major finding of this research is
that it moves up the human visual timeline. Reid said,

(02:52):
we now know that the fetus actively engages with visual
information in the prenatal environment. The head movement was a
deliberate movement to track the stimuli that we presented. This
means that we can now look at many other aspects
of fetal vision. The study has laid the groundwork for
future delving into fetal vision because as it stands right now,
little is known about how much fetuses can see. Red said,

(03:15):
a week old infant has very poor focal vision. It's
all blurred. The same will be true for fetus a
few weeks before birth. We know that premature infants can
see shapes, lights, and details, but that's once they are born,
and it could be that the prenatal environment is different.
We need to find that out. Reed's group plans to
investigate whether fetuses can discriminate between quantities or numbers, which

(03:37):
he notes is something that newborns can do. He said,
if the fetus can do this too, this tells us
a lot about fetal cognitive abilities. We're also keen to
look at how the fetus sees motion. Babies prefer to
look at animate or biological motion. If the fetus has
this preference, this would suggest that experiences they have had
engaging with their own body may have given rise to
these preferences. Today's episode was written by Ali A. Hoyt

(04:05):
and produced by Tyler Clang for iHeart Radio's How Stuff Works.
For more on this and lots of other developing topics,
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