Relatively little research has been conducted on the effect of hearing an unfamiliar native English accent. This paper tests listeners with varying levels of familiarity with the Glaswegian linguistic environment, presenting them with naturalistic minimal pairs such as hut/hurt – produced by speakers raised in Glasgow – in two-alternative-forced-choice tasks. The results of Experiment 1 show a benefit of long-term familiarity in discriminating minimal pairs with derhoticised /r/, a phonetically eroded form of postvocalic /r/ in working class Glaswegian. Native Glaswegian listeners displayed high sensitivity to difference (d’), and low response bias (c) towards hearing either rhotic or non-rhotic words, indicating accurate perception. Unfamiliar listeners were less sensitive to stimulus difference, and were biased towards hearing plain vowels, demonstrating their unfamiliarity with Glaswegian /r/. Non-rhotic English listeners with a moderate level of experience with Glaswegian showed an effect of ‘perceptual hypercorrection’, i.e. over-reporting /r/ presence. Experiment 2 found that, following a short period of exposure, English listeners with very little experience with Glaswegian also started to show hypercorrection, suggesting rapid adaptation to novel phonetic detail. These results may be explained by some general principles underlying exemplar and hybrid theories, and contribute to the ongoing research into the complex nature of Scottish /r/.