Babies learn to recognise human faces while still in the womb

Incredible 4D scans show fetuses turning their heads to look at 'face-shaped' lights

Babies may begin learning to recognise human faces while still in the womb, new research has found. Scientists discovered that unborn infants react to light when it is projected through the wall of their mother's uterus if it looks like a face. Using high-quality four dimensional ultrasound scans, they saw the fetuses turn their heads to look towards the light if it was in the shape of a human face.

Professor Vincent Reid, a psychologist at Lancaster University who led the research, said the findings provide new insights into how babies' visual systems develop: 'We know from babies that they prefer to look at faces more than any other stimulus. We have now shown that the fetus can distinguish between different shapes, preferring to track face-like over non-face-like shapes. The newborn has very poor visual acuity so the fetus will have a similarly poor ability to focus. So whatever the fetus sees is likely to be blurry.'

Researchers shone dots of light arranged to look either like the eyes and mouth of a human face through the uterus wall of expectant mothers who were 34 weeks (8 months) pregnant. Babies after birth are known to prefer looking at dots of light arranged in this shape.

The scientists used computer modelling to see how the light would change as it passes through the mother's skin and abdomen so they could produce the same arrangement of light. Their study, which is published in the journal Current Biology, showed that when this face-like image was projected through the uterus, the babies turned their heads to look at it.

When a similar arrangement of light that was used to make the face look upside down, and so harder to recognise as a face, the fetuses did not react. Professor Reid said this could happen because the foetus is hardwired to recognise human faces or its experiences in the womb prime it to recognise these sorts of 'face-like' shapes.

He said: 'I think the second option is more likely. I believe that it is likely this bias to look at faces is triggered by exposure to patterned light in the womb and is due to prenatal visual experiences. It is possible that the maternal rib cage could introduce variation in light penetrating the womb and this may be enough visual information to create this bias. It suggests that the upper visual fields is developmentally more advanced and sensitive than the lower visual fields.'

If correct, the findings suggest that exposure to light while in the womb could be just as important to the development of our eyes as it is after we are born.

Professor Reid warned that expecting mothers should avoid shining bright lights through their abdomen in case they damage their unborn child's eyes. He said: 'Our study used carefully controlled stimuli at a low level of brightness. I would discourage anyone from shining lights at a fetus as the intensity may be too bright and could be aversive or distressing.' (© Daily Mail, London)