Phonological code retrieval during picture naming: Influence of consonant class.

Investigations of the time course of various stages of lexical processing have indicated either early or late onset of brain activation for phonological code retrieval. The basis of the differential findings is unclear, but factors related to segmental phonology appear to be part of it. The purpose of the present study was to determine whether phonological encoding is influenced by consonant type. Undergraduate students were presented pictures of common and familiar objects to name. Each picture label had an initial liquid (/l/, /ɹ/) or a stop (/b/, /d/) consonant. Accuracy of picture naming was high and comparable for the two stimulus sets. However, words beginning with liquids elicited larger N2 ERP responses than did those with initial stops. Cluster permutation analysis indicated that the ERP responses elicited by words in the two stimulus sets differed between 293 ms and 371 ms post picture onset. These findings point to a late onset of phonological code retrieval. They have implications for segmental phonology and/or motor planning and execution of speech.