We know that babies don’t just see in black and white. But what colours can they see – and how key is it to their development? By Nicola Davis
Sitting in a padded car seat, a small black and white bullseye stuck to his cheek, four-month-old Teo Bosten-Lam gazes at a computer. The screen is a mottled grey, like the snow on a old-fashioned television, but in the top right-hand corner is a deep blue circle. Teo has spotted it. He glances at the circle and, as he does so, it morphs into a smiley face and a triumphant jingle fills the darkened room. Buoyed by the reaction, he looks around. Suddenly a black and white spinning disc appears on the screen, issuing a sound that can only be described as “boing”.
“Babies can’t resist the black and white swirl things,” says researcher Alice Skelton. “When they look away we play it and it brings them back to the screen.” A PhD student in the baby lab at the University of Sussex, Skelton is attempting to unpick a conundrum that has fascinated parents and scientists alike: when it comes to colour, exactly what can babies can see?
It’s a mission that takes technology: Teo’s ability to pick up on colour is being probed with an eye-tracking system. The sticker on his cheek directs the camera to his face, while his corneal reflections and the position of his pupils are automatically detected. “What we are looking to see is, do you have to have a more saturated blue for a baby to see it than you would for a red, for example,” says Skelton. If Teo can see a colour, the novelty will attract his attention, triggering the smiley face and jingle. And this isn’t the only ingenious idea. At the first sound that indicates our participant is becoming fed up with this science lark, the screen flashes to a clip from the 1980s cartoon Dogtanian. Teo, once again, is transfixed.
To a baby, the world changes rapidly. At birth, everything is a blur, with visual acuity around 5% of that for an adult. Stereoscopic vision has yet to kick in, with babies unable to perceive depth until several months old, while faces are only discernable at around 30cm – a distance similar to that between a mother’s face and her breast. But change is rapid. “The early stages of learning to see colour and basic forms happen relatively quickly,” says Alex Wade, professor of psychology at the University of York, and an expert in visual processes. By the age of six months, babies have more or less adult levels of visual acuity.
Just how such changes occur, and their impact on how a baby understands the world, is the driving force behind research at baby labs around the world. A handful of such centres are located at universities in the UK, probing myriad aspects of development from the role of sleep to how babies recognise faces and even how they learn to distinguish words in human speech.
Anna Franklin, head of the baby lab at the University of Sussex, is attempting to unpick how colour is understood by infants. “It is a myth that babies see in black and white,” she says, pointing out that studies have found that newborns can see large, intense patches of red on a grey background.
An expert in infant colour vision, Franklin is engaged in fundamental research answering questions ranging from how colour vision develops in infancy to why children with autism often have colour obsessions. Her research has aided the development of infant toys, theatre and TV shows, while the team is currently working on early tests for colour vision deficiencies - an endeavour that could help to prevent children from encountering problems when faced with the myriad colour-based learning systems found in the classroom.
That we can see the world in glorious colour at all, Franklin points out, is down to specialist cells in the retinas of our eyes. Known as cones, these cells come in three types – those sensitive to long, medium, and short wavelengths of light. “Signals from cones are combined in different ways - so, for example, the middle and long wavelength cones are combined to give you what is called a red-green pathway – [how much] redness or greenness there is in a colour,” explains Franklin.
While babies are born with all three types of cone, it takes time for the cells to mature, and for the brain to make sense of the signals. By two months, babies can tell red and green colours apart; a few weeks later, they can also tell apart blues and yellows. But the colours need to be strong. “If you show [a baby] some kind of washed-out green they won’t be able to see it, even if they can see a really intense green,” says Franklin. While the ability to see desaturated colours improves as infants mature, questions abound, not least as to whether all colours need to be just as saturated for babies to spot them.
And so it is that Skelton, Franklin and I find ourselves in a darkened lab with Teo - his eyes flicking around a screen. The results so far are intriguing. Testing more than 40 babies, Skelton has found that, even at four months, they, like adults, need blues and yellows to be more intense to see them than reds and greens. Research by Franklin and her team has also shed light on a surprising phenomenon: babies can categorise colours. Categorisation is something we take for granted as adults. “When you come in and you have to sit on a chair, you don’t have to stand around working out what a chair is – you know what a chair is,” points out Skelton.
But where this ability comes from is unclear - not least, when it comes to colours. “Different languages will [categorise colours] differently, so some languages will put all the greens and blues in one category and have one label for that, whereas in English, obviously, we have separate words,” says Franklin. Until recently, the accepted view was that colour categorisation was arbitrary, with distinctions rooted in culture and language. But Franklin suspected there was more to the story. She devised a number of tests, one of which involved presenting babies with a coloured screen on which a dot appears. The background screen is either from the same colour category as the dot, as defined by the English language, or from a different one - for example a green background with a blue dot. A coloured dot captures the baby’s attention, and how quickly they look at it offers clues as to how different it appears from the background colour.
Similar experiments were carried out on nine-month old babies by Asifa Majid, professor at Radboud University in the Netherlands. “You can see that infants look more quickly towards a coloured dot when it comes from a different colour category,” she explains. In other words, babies can tell that different colours of blue are all, well, “blue”. Colour categories, it seems, are not just down to language, they are in some way “hardwired”.
Franklin and her team started exploring just how many colour categories babies possess. More than 170 babies were recruited for the experiment, with each repeatedly shown two squares of the same colour, then two of different colours. “The upshot is babies have got five colour categories, we think: red, green, blue, purple and yellowish-brown,” says Skelton. Further categories, such as orange and pink, appear to emerge later with language.
Why, then, don’t all cultures have the same categories? “It is likely that languages develop or tinker or modify on that universal, innate template and tinker with it according to the needs of their culture,” says Franklin.
Much is still unknown: when, and how, colour categorisation shifts from the sensory process in babies to language-based categorisation in adults. And, “we don’t really know when children really fully understand that a colour is a property of an object and that it is constant,” says Skelton. “The questions we are asking are really the foundation of what does the world look like to a baby and how they learn about that.”
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