BrainStuff Classics: 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 classic episode of BrainStuff, based on this article: https://health.howstuffworks.com/pregnancy-and-parenting/pregnancy/fetal-development/what-do-babies-see-before-birth.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to Brainstuff, a production of iHeartRadio. Hey brain Stuff,
Lauren Vogelbomb here with a plastic episode for you from
the vault. In this one, we look at the first
things that we humans may actually be able to look at.
Period A growing fetus doesn't even develop retinas until the
third trimester, and we can't ask them what they see

(00:24):
at that point, but researchers have studied how they respond
to visual cues during that home stretch before birth. Hey
brain Stuff, Lauren voel Bomb here. It might seem like
fetuses aren't 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

(00:45):
an independently living, breathing human being is a big enough job. However,
research 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.

(01:08):
We spoke via email with Vincent Reid, the lead researcher
and a 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 at faces
over any other shape, so it was logical to explore

(01:30):
the development of this preference before birth. The researchers examined
a total 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

(01:52):
to thirty six weeks. Site is the final sense to
develop inside the womb, with eyes staying closed until around
gestational 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 non invasive

(02:15):
attempts to assess the baby's visual capabilities. To do so,
the scientists shone lights through the maternal tissue. Reid explained
the light consisted of three dots. When these are arranged
to represent two for 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 forty ultrasound to

(02:39):
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 face like dots weren't as appealing. Reid noted that
newborns don't find these configurations very interesting either. Although subtle

(03:00):
attraction to the facelike configuration of three dots makes a
big difference in what we understand about developing site, Reed 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. Reed said,

(03:20):
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. Reed said,

(03:42):
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. Reid's group plans to
investigate whether fetuses can discriminate between quantities or numbers, which

(04:05):
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've had engaging
with their own body may have given rise to these preferences.

(04:33):
Today's episode is based on the article what do Babies
See before Birth? On how stuffworks dot com written by
Leah Hoy. Brain Stuff is production of iHeartRadio in partnership
with how stuffworks dot Com and is produced by Tyler Klang.
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