Auditory predictions are phonological when phonetic information is variable

An emerging body of studies has claimed that exposure to phonetically varying speech sounds results in strictly phonological representations of speech sounds by the brain’s auditory prediction system (Cornell et al., 2011; Eulitz & Lahiri, 2004; Hestvik et al., 2020; Hestvik & Durvasula, 2016; Phillips et al., 2000). We test this claim by measuring mismatch negativity (MMN) to a subcategorical contrast with two sets of phonetically varying standards. When controlling for non-prediction related contributors to the MMN, we find a mismatch in a late time window. However, the mismatch effect is only significant for participants who perceived the contrast as an across-category contrast (/t/ vs /d/). Additionally, we find no modulation of mismatch amplitude predicated on phonetic distance between standards and deviant. Taken together, this indicates that the prediction generated by the auditory system in response to phonetically varying speech sounds is indeed phonological and lacks any fine-grained phonetic content.