Even babies agree roses are red, psychologists say
Apparently听a rose by no name at all looks just听as red.
Even before learning to speak听, along with four other colors, according to a听paper published in April in the journal Proceedings of the National Academy of Sciences. The study presents the strongest evidence yet that color categories spring more from biology than from culture, the latest round in the nature vs. nurture debate of language and thought.
When linguists first wondered where color categories came from, physicists had no answer. The rainbow features no obvious breaks, yet most听English speakers have no trouble splitting the spectrum according to Roy G. Biv.听, with different cultures slicing the rainbow in random ways, but field researchers found that even completely unrelated languages often听, hinting that vision mechanics were stacking the deck in nature鈥檚 favor.
Now,听the most complete听infant color study to date reveals that 4- to 6-month-old babies can tell the difference between many of those same colors, despite not knowing the words for them.
鈥淲e were able to compare the way that our babies were looking at the colors to the way adults in the world talk about colors,鈥� says lead author Alice Skelton, a听PhD听student at the University of Sussex in England.
Newborns can鈥檛 tell scientists what colors they see (that鈥檚 the point), but they can vote with their attention. Babies听shown听the same color in repetition eventually lose听interest and look away, but a new color tends to听hold their gaze. By exposing 179 infants to dozens of samples, scientists could infer which hues looked novel to each child.
Similar setups in the past had shown infants can sort colors, but this study was by far the most comprehensive to date. Ohio State University psychologist Angela Brown praised the experiment for its 鈥済inormous data set,鈥� which covered the whole hue circle.
鈥淧revious work with babies has concentrated on one particular corner of color space ... and it鈥檚 just really hard to get a convincing picture of infant color categories from that piecewise approach,鈥� continues Professor Brown, who was not involved in the research. 鈥淚 frankly had sort of despaired that anyone was going to succeed in doing what Skelton et al. have managed.鈥�
And the picture they got was more familiar than even Ms. Skelton had hoped. The infants could reliably distinguish between red, yellow, green, blue, and purple, five categories already well-known to researchers from听听representing dozens of languages.
鈥淲e were perhaps expecting some reflection of that in our infant data but it wasn鈥檛 necessarily guaranteed,鈥� she says.
In the nature vs. nurture debate, it鈥檚 a big win for nature. 鈥淚f [pre-verbal infants] understand the same color categories as adults, then language can鈥檛 be responsible for the color categories,鈥� explains Brown. At 6 months, nurture just hasn鈥檛 had time to muck things up.
But nature鈥檚 victory isn鈥檛 perfect. 鈥淚t鈥檚 not like it鈥檚 absolutely set in stone. Culture is able to build upon it,鈥� says Skelton. These divisions aren鈥檛 so much hard biological limits as they are a starting point from which language听can then diverge.
For example, linguists have found languages that lump 鈥済reen鈥� and 鈥渂lue鈥� into a kind of听听color, despite the infant preference for two separate categories. Reduced color vocabularies are more common in pre-industrial societies, where artificially colored objects are rare.听Skelton calls these 鈥渦se it or lose it鈥� cases: 鈥淐ategories are all about being efficient鈥� If听you鈥檙e not making that distinction听between blue and green, it鈥檚 not efficient to keep hold of it so it kind of goes away.鈥澨�
After听all听we don鈥檛 name the millions of colors we can see, in part because it would be overwhelming, explains Brown.听
So why is it these five that get special treatment? Skelton discovered that if they sorted their data based on the听听in the eye, they got a graph where just about one color cluster fell into each quadrant.
鈥淭hat can explain four out of five of our color categories, and then the fifth one [red/yellow] 鈥� we don鈥檛 know yet basically,鈥� she says.
Brown finds this result 鈥渞eally interesting,鈥� but cautions against over-interpreting it. While the graph is a good description of what鈥檚 happening in the eye and optic nerve, a number of poorly understood image-processing circuits separate it from the high-level representation of color accessible to the conscious mind, the one babies might actually act on.听
鈥淭he problem is that it is not a perceptual color space,鈥� Brown says. 鈥淚t鈥檚 a great step in unraveling that chain connecting the optic nerve with whatever higher level system we鈥檙e using ... but it will take a long time to fully understand the implications of this analysis.鈥�
But just because we may all share a biological basis for color doesn鈥檛 mean dorm room pontificators are out of a job. No experiment can tell us if my colors are your colors, Brown says. 鈥淲e can test various aspects of the perception of blue [reaction time, memory]..., but that is never going to get to the quality of blue.鈥�
Internal sensation aside, Skelton says physical color perception does vary, but that鈥檚 beside the point. 鈥淭here are things like the distribution of color receptors in our eyes that will be different, so my red is probably not your red, but for communication听purposes听it doesn鈥檛 matter.鈥�
She鈥檚 more curious about why our adult vocabulary grows to include mauve, magenta, and crimson. 鈥淗ow we move from these five categories into six, seven, eight, nine categories depending on what language you鈥檙e speaking is a really, really interesting question.鈥�
Brown too sees colors as just the start. Their universality and reproducibility make them easy to study, opening the door to more general theories of perception and language.
鈥淚t鈥檚 proven to be an extremely rich field of study for understanding how we begin to unite what we see to what we say,鈥� she says.
