How the brain responds to possible and impossible words: an MMN investigation of wordhood in English

Pseudowords and nonwords have served as cornerstones of psycholinguistic and neurolinguistic research, allowing researchers to examine language processing in the absence of lexical-semantic activation. To examine how graded phonotactic violations modulate pseudoword processing, we employed an auditory oddball mismatch negativity (MMN) paradigm with independent comparisons among four English stimuli ranging from phonotactically licit forms to combinations impossible in English: [krεlz], [kreɪlz], [krεls] and [kreɪls]. Importantly, such violations are not only reducible to the effects of individual segments but also arise from the interaction between vowel quality and word-final structure. We observed asymmetric MMN responses consistent with these combinatorial constraints, particularly for forms whose phonological patterns implied morphological structure. Robust MMNs occurred whenever the maximally illicit form served as the deviant, indicating strong perceptual conflict. Together, our findings reflect a cognisance of multiple phonological and morphophonological constraints, rather than a simple distinction between possible and impossible words.