一直好奇：嬰兒出生前到底能看見什么？

It might seem like fetuses aren't up to much other than growing in the cozy, warm environment that is the mother's womb. However, new research published in the journal Current Biology shows that third-trimester babies have vision capabilities much more advanced than previously thought. And they can choose what they want to look at.

在大多數(shù)人的印象中，胎兒就只會在母親子宮里靜靜成長，別的啥都不會做。但研究卻發(fā)現(xiàn)，孕晚期胎兒的視力比我們想象中要發(fā)達得多。他們甚至能夠選擇自己想看什么。

Researchers from Lancaster University in the United Kingdom were keen on expanding the understanding of fetal sight capabilities. "We have been able to explore the use of all the fetal senses except vision up until now," explains lead researcher and professor of psychology Vincent Reid in an email interview. "There is a lot that we know about newborn babies and their vision, but almost nothing with fetuses just before they are 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 the development of this preference before birth."

英國蘭卡斯特大學(xué)的研究者就希望進一步了解胎兒的視力。主要研究者Vincent Reid稱，“關(guān)于胎兒的其它感官，我們已經(jīng)有了很多了解。我們也知道了有關(guān)新生兒視力的很多事情，但胎兒出生前的視力如何，我們卻幾乎完全不知道。新生兒很擅長辨別人臉，比起其它形狀的事物，他們也更喜歡觀察人臉。所以我們可以假定，他們在出生前就發(fā)展出了這一偏好。”

A total of 39 fetus were examined (there would have been more, but some of the babies were in deep sleep because they missed the memo about participating in a research study, while others experienced poor image quality). They ranged in gestational age from 231 to 252 days, and were all single births.

接受檢查的總共有39個胎兒(本來有更多的，但有的孕婦忘記過來檢查，也有的是因為拍出來的圖像質(zhì)量太差)。胎兒的胎齡都在231-252天之間，并且都是單獨一胎。

Obviously, since the fetal participants were still cooking in their moms' wombs, so the researchers resorted to noninvasive attempts to assess their visual capabilities. To do so, the scientists shone a light through the maternal tissue. "The light consisted of three dots," Reid explains. "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 a 'face' but an image that was 'face-like.'"

由于胎兒還在子宮內(nèi)發(fā)育成長，研究者需要借助非侵入性手段了解他們的視力。科學(xué)家使用光線在母親體外進行照射。Reid稱，“這些光線包含三個點，模仿人臉的兩只眼睛和一個嘴巴。新生兒很喜歡看人臉，所以我們雖然不能直接給胎兒展示一張臉，但可以使用類似人臉的形狀。”

The researchers used 4D ultrasound 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-face-like dots were none too appealing. "Turning it upside down means that newborns do not find it interesting," Reid notes.

研究者使用4D超聲波觀察胎兒是否會轉(zhuǎn)動頭部來回應(yīng)這些光點。他們還將這三個點倒轉(zhuǎn)了過來(這樣就不像人臉了)，結(jié)果胎兒就沒那么感興趣了。

Although subtle, attraction to the face-like configuration of three dots makes a big difference in what we understand about developing sight. "It means that we have this preference even before we are born," Reid says. "[It] is either due to being innate or due to experiences prior to birth."

胎兒對模擬人臉的三個光點很感興趣。Reid說道，“這意味著我們早在出生前就發(fā)展出了這個偏好，這可能是天生的，也可能跟在子宮內(nèi)的經(jīng)歷有關(guān)。”

Another major finding of this research is that it moves up the human visual timeline. "We now know that the fetus actively engages with visual information in the [prenatal] environment," Reid says. "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."

該研究的另一重大成果是將人類的視覺時間軸往前推了一截。研究者稱，“我們現(xiàn)在知道了，胎兒會主動觀看事物。在觀察中我們發(fā)現(xiàn)，當(dāng)光點出現(xiàn)時，他們會主動做出頭部運動。這樣的話，我們以后就可以進一步研究胎兒的視力了。”

Indeed, 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. "Nobody has looked at this before," Reid says. "A week-old infant has very poor focal vision. It is all blurred. The same will be true for a fetus a few weeks before birth. We know that premature infants can see shapes, lights, and details. But thatis once they are born, and it could be that the prenatal environment is different. We need to find out."

有了這個研究作為基礎(chǔ)，科學(xué)家就能進行更多調(diào)查了。幾周大的嬰兒焦點視覺很差，他們看到的東西都是模糊的，而出生前幾周的胎兒應(yīng)該也是。Reid的團隊也將研究胎兒是否能夠辨別數(shù)量和觀察運動，因為新生兒就能這么做。假如他們可以，這將刷新我們對人類視覺發(fā)育的認(rèn)識。