3rd-Trimester Fetuses May React to Face-Like Images

It is well known that infants prefer looking at faces over other objects. Now, a new study finds that this preference begins before birth.

By projecting light into the uterus of pregnant women, researchers found that fetuses in the third trimester (34 weeks gestation) will turn their heads to look at face-like images over other shapes.

The findings, published in the journal Current Biology, are the first to show that it’s possible to explore visual perception and cognition in babies before they are born.

“We have shown the fetus can distinguish between different shapes, preferring to track face-like over non-face-like shapes,” said Dr. Vincent Reid of Lancaster University in the United Kingdom. “This preference has been recognized in babies for many decades, but until now exploring fetal vision has not been attempted.”

Although technical barriers had prevented earlier studies of fetal vision and behavior in the womb, the researchers knew that those challenges could be overcome thanks to high-quality 4D ultrasound. Scientists also knew that it’s possible for light to penetrate through human tissue and into the uterus, where a fetus could see it.

For the study, the research team evaluated the reactions of 39 fetuses to face-like patterns of light shown to them in both upright and inverted orientations. The projected light moved across their field of vision while researchers watched their responses through 4D ultrasound.

The developing babies turned their heads to look more often at face-like stimuli that were upright than those that were presented to them upside down.

“There was the possibility that the fetus would find any shape interesting due to the novelty of the stimulus,” Reid said. “If this was the case, we would have seen no difference in how they responded to the upright and upside-down versions of the stimuli. But it turned out that they responded in a way that was very similar to infants.”

The findings show that infants’ preference for faces begins in the womb, suggesting that there is no learning or experience after birth required. In addition, it was confirmed that fetuses have enough light to see and have visual experiences in the womb.

However, Reid says that he discourages pregnant mothers from shining bright lights into their bellies.

The researchers are now working to improve the light source used in the current study to prepare for  further investigation of fetal perception and cognition in the womb.

For example, they say, newborns can discriminate numbers and quantities. Next they want to determine whether a fetus in the third trimester also has that capacity.

Source: Cell Press