A linguist tracked an island's vowels and found pride, not class, driving the change

In 1961, William Labov recorded Martha's Vineyard islanders pronouncing 'ai' and 'au' with increasingly centralized vowels. The shift was strongest among locals who identified with island life and resented summer tourists, not simply a matter of age or class. It became sociolinguistics' founding study, showing sound change spreads through identity and attitude as much as contact.

— William Labov, The Social Motivation of a Sound Change — Word, vol. 19, no. 3, 1963