The classification of oral stops after tautosyllabic /s/ in English is an old phonological problem to which different solutions have been proposed. In an attempt to provide experimental evidence on the classification of oral bilabial stops after tautosyllabic /s/ by native speakers of English, a concept formation experiment was conducted. The results showed that out of the four main phonological theoretical views on the classification of oral stops after tautosyllabic /s/, the solution which treats those speech segments as allophones of the phonemes /p, t, k/ is the most plausible from the point of view of language users' classificatory behaviour
