Human foetuses like to look at face-like patterns
Using a new technique, UK scientists have shown that developing babies preferentially look at patterns of light resembling faces.
Using 4D ultrasound scans, University of Lancaster researcher Vincent Reid and his colleagues studied how 39 developing babies responded to face-shaped patterns of light shone through their mother's abdominal walls.
Preferential interest in a "face", they reasoned, would be indicated by the baby turning its head to follow the stimulus if it moved.
To demonstrate this, the team swept their face-pattern across the mother's pregnant belly 5 times and tracked the foetal movements. Sure enough, they found, a face presented the "right way up" relative to the baby elicited pursuit movements. An inverted "face", on the other hand, was regarded with much less interest.
These results mirror the responses seen when babies are tested in a similar way after birth, showing that interest in face-shaped stimuli is not something that a baby learns as it grows after birth but instead is an ability that is already in place by the time it is born.
Human foetuses first open their eyes from about 24 weeks of development and there are functional connections established between the eye and the brain from before this time. But whether developing babies can perceive anything at this stage wasn't known.
Now these new findings, published this week in the journal Current Biology, show that babies do appear to be able to "see" inside the uterus and may well be using these early visual experiences to drive the correct development of their visual pathways.
Indeed, some light filtering through the mother's abdominal wall may be critical to the process.
"A recent study on mice showed that you need light exposure in the uterus to prepare the eye properly so it can see after birth," Reid explains. "Although no one's done the experiment yet to measure how much light is actually present inside the human uterus..."
At the moment the Lancaster team do not know how, neurologically speaking, the babies they studied are "seeing", or what parts of the developing brain are responsible for the effects, "but this is a new technique that's enabling us to study a range of important developmental questions in a whole new way."