Like any other infant, one born blind must learn to map the words she hears from her caregivers onto things in the world. Apple, ball, give, no—her understanding of each pivots and adjusts until she, too, has reached her community’s consensus on how those words work.
Curiously, however, her inability to see doesn’t inhibit this mapping process, at least in the long run. As an adult, her words for the visual world—even how she thinks about other people seeing—will likely end up resembling the words and beliefs of a sighted person.
How do we know? In 1978, a Princeton University researcher named Gloria Marmor carried out one of the best early studies on how blind adults conceive of basic color terms. In the study, participants were handed 36 cards, each containing a pair of color words—green and gold, for instance, or green and red. They then ranked the color pairs in terms of similarity: Are green and gold more similar than green and red? Their responses were used to build “color wheels” that described how they believed the terms related to each other.
When color wheels from early-blind individuals (those blind since infancy), as well as those blinded later in life, were compared to the color wheels of sighted people, some differences were apparent. The early-blind group tended to invert a few colors: gold and yellow, purple and violet. This group was also more variable in its responses than the other two. But far more striking were the likenesses: all three groups had “extremely similar” ideas about which colors resembled which others. (When Marmor asked her early blind participants how they knew so much about colors they’d never seen, they referenced “chance conversations in which colorful objects and events like rubies and sunsets were discussed” and “conversations about how to dress to please the sighted public.”)
In the intervening decades, other studies have confirmed that blind people use words, even those that describe visual phenomena, a whole lot like we do. In a more recent study, blind and sighted adults listened to pairs of words and proceeded to rate, on a scale from one to four, how related they were in meaning. Some words conveyed some visual information (motion verbs, for instance), and others did not (mental verbs like think). But for all types of words tested, blind and sighted participants performed similarly—and, according to evidence from fMRI, even seemed to engage the same brain regions to do so.
Some studies do turn up minor differences in the way blind and sighted people conceive of the world. A 2007 study found that that even though blind participants know full well what color various fruits and vegetables are, they are nonetheless less likely than sighted participants to use color to determine which of three fruits or vegetables—a banana, a pineapple, a lime—is the “odd man out.” (For other categories, like household items, where color is less relevant, there were no differences between groups.)
Still, it’s the similarities that add up. Another recent study asked how blind individuals understand other people’s visual experiences. Participants lying in an fMRI scanner heard short stories about characters who either saw or heard something—a message from a friend, for instance. Both congenitally blind and sighted participants processed the information differently in the brain depending on whether it had been seen or heard. Crucially, however, despite having no first-hand experience seeing, the congenitally blind individuals’ neural representations of seeing were no different from those of the sighted.
To be clear, none of the research I’ve described suggests that blind and sighted children acquire these words and beliefs at the same pace, or in the same way. But it does suggest that learning to label or represent visual experiences doesn’t hinge on one’s own visual experiences. Language is rich, robust, and redundant, copiously so, and sufficient for teaching the subtle differences between brown and caramel, glittering and flickering—no world necessary. And then there are always those chance conversations about sunsets and outfits.
