

When infant eyes absorb a world of virgin visions, colors are processed purely, in a pre-linguistic parts of the brain. As adults, colors are processed in the brain's language centers, refracted by the concepts we have for them.

How does that switch take place? And does it affect our subjective experience of color? Such tantalizing questions, their answers still unknown, are raised by this developmental shift in color categorization, described today in the Proceedings of the National Academy of Sciences.

To test the phenomenon, a team of British and English researchers asked adults and infants to focus on a briefly flashing target circle.

Sometimes the target appeared in the subjects' right visual fields

– roughly speaking, the right half of a person's field of vision, which is transmitted from the eyes to the brain's left hemisphere, where language processing also takes place. Sometimes the targets appeared in the left visual field, which connects to the pre-linguistic right hemisphere.

When asked to pick out a target against a similarly-colored background

– a more mentally demanding task than distinguishing between different colors – infants performed better when the target appeared in their left visual fields. Adults, by contrast, had an easier time with targets in their right visual fields.

Over the course of our lives, it appears that an unfiltered perception of color gives way to one mediated by the constructs of language.

Does this mean that adults and infants see the same colors differently?

"We don't know," said study co-author Paul Kay.

But might adults see colors differently? That seems plausible.

"As an adult, color categorization is influenced by linguistic categories. It differs as the language differs," said Kay, who is renowned for his studies on the ways that different cultures classify colors. He cited recent research on the ability of Russian speakers to

detect shades of blue [pdf] that English speakers classify as a single color.

How does the switch to a language-bound perception of color take place?

"That's the $64,000 question," said Kay. "We have every reason to believe that learning a language has a lot to do with it – but [as for] how that works, it's early."

Categorical perception of color is lateralized to the right hemisphere in infants, but to the left hemisphere in adults [PNAS]

Image: Doug Wilson

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