Does the language you speak change what you see?

Russian divides the blue range into two basic colour terms, lighter and darker, with no word covering both. English has one.

In a 2007 study, speakers of each language saw three blue squares and indicated which of the lower two matched the one above. Russian speakers were faster when the two candidates fell on opposite sides of their category boundary than when both fell inside one category. English speakers showed no such effect.

The advantage disappeared when participants performed a verbal task at the same time, and survived when the interfering task was spatial. The spatial task is the control: it shows the loss came from occupying language, not from doing two things at once.

It is not evidence that a speaker cannot perceive a distinction their language lacks. English speakers matched the blues as accurately as Russian speakers did, and put a light and dark boundary in almost the same place. What they lacked was the speed-up for crossing it.

The difference was a little over a tenth of a second, and only when the two blues were close; on easier pairs there was none. That is the honest size of the effect.

Whether it holds is now argued. In 2020 Martinovic, Paramei and MacInnes repeated the task in two experiments, with seventeen and then twenty Russian speakers, and found no speed advantage at the boundary. They argue the original result may be an artefact: darker blues are slower to tell apart, and the Russian group was slower overall.

A review written two years later put the position as Whorf being half right, in two ways: language influences colour perception “primarily in half the visual field”, and colour naming across languages is shaped by both universal and language-specific forces.

That is a specific, checkable version of a claim that spent decades being neither. It also limits it. A perceptual difference that appears in one half of the visual field and not the other is not a different world. And the half-field result has not held up in later tests: Witzel and Gegenfurtner ran ten versions of the original experiments with 230 observers and found the category effect equally strong in both halves.

Comparable effects have been reported for spatial description, for how much blame people assign when an accident is described with or without an agent, and for how time is laid out. The time result is contested: January and Kako reported six failed attempts to repeat it, and Boroditsky and colleagues reported new evidence for it in 2011.

Colour is the cleanest case because the stimulus can be specified physically, and even there the replication turned on whether two pairs of blues were really equally hard to tell apart. Most of the interesting claims are about domains where nothing can be specified that precisely, which is why they stay argued.