Distinguishing underlying and surface variation patterns in speech perception

This study examines the relationship between patterns of variation and speech perception using two English prefixes: “in-”/“im-” and “un-”. In natural speech, “in-” varies due to an underlying process of phonological assimilation, while “un-” shows a pattern of surface variation, assimilating before labial stems. In a go/no-go lexical decision experiment, subjects were presented a set of “mispronounced” stimuli in which the prefix nasal was altered (replacing [n] with [m], or vice versa), in addition to real words with unaltered prefixes. No significant differences between prefixes were found in responses to unaltered words. In mispronounced items, responses to “un-” forms were faster and more accurate than to “in-” forms, although a significant interaction mitigated this effect in labial contexts. These results suggest the regularity of variation patterns has consequences for the lexical specification of words, and argues against radical underspecification accounts which argue for a maximally sparse lexicon.