Color categorization groups perceived colors into classes, such as those associated with color names. It is distinct from merely detecting that two stimuli differ. A study can separately ask what a sample is called, which comparison matches it and how long the response takes.
Jonathan Winawer and collaborators compared Russian and English speakers on a speeded discrimination task using blue stimuli that crossed the Russian light-blue/dark-blue naming boundary. Russian speakers showed a category-related advantage that was disrupted by verbal interference. The design compares naming boundaries, discrimination performance and a concurrent task, rather than inferring color perception from vocabulary alone.[ref]
Russian blues reveal effects of language on color discrimination by Jonathan Winawer and others. 2007, abstract; discrimination task and verbal versus spatial interference conditions
The result constrains how linguistic processing can contribute during a task. It does not show that a person cannot distinguish unnamed colors, or that all aspects of color vision are fixed by the words of a language. Categorical perception, naming and reaction time provide related but different measurements.
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