RESUMEN
This study aims to examine the perception of English vowels by Greek monolingual and bidialectal speakers of English as a second language (L2) and assess the predictions of the Universal Perceptual Model (UPM). Adult Cypriot Greek (CG) bidialectal speakers and Standard Modern Greek (SMG) monolingual speakers participated in classification and discrimination tests. The two groups were matched for various linguistic, sociolinguistic, and cognitive factors. Another group of adult English speakers served as controls. Data analysis has been conducted with the use of Bayesian regression models. The results of the discrimination test were predicted by acoustic similarity only to some extent, while perceptual similarity predicted most contrasts, confirming the hypotheses of UPM. A crucial finding was that bidialectals outperformed monolinguals in the discrimination of L2 contrasts. The advantage observed in bidialectals could be attributed to the greater flexibility of their speech categories, stemming from exposure to more diverse linguistic input.