Asymmetries in the perception of speech production errors

Psycholinguistic research concerned with the mental reality of linguistic units has long relied on speech error data which are traditionally collected by means of impressionistic transcription. Evaluation of these data has been taken to support the view that in word form encoding, the most common form of speech error originates from a categorical mis-selection that shifts a segment to a wrong position within a prosodic 'frame.' Asymmetric distributions in such segmental speech errors have been used to argue for coronal underspecification. However, several relatively recent studies investigating speech errors instrumentally have challenged these assumptions by showing that speech errors are not confined to a categorical position-exchange of segmental units. Specifically it has been shown that the gestures that compose a segment may intrude individually and show up in an incorrect temporal position with variable articulatory magnitude. The overall observed bias for gestural intrusion as opposed to reduction has the consequence that often two gestures (one appropriate, one intruding) are produced simultaneously. The current study tests the perceptual consequences of these phonologically ill-formed errors by presenting listeners with utterances collected in an EMMA speech error experiment. Results indicate that biases in the perception of the ill-formed errors may be the source of asymmetries in error distributions as they have been observed in speech error corpora. Specifically claims about coronal underspecification that have been made on the basis of data collected through transcription are not supported by our study.