Semantic similarity promotes interference in the continuous naming paradigm: behavioural and electrophysiological evidence

We investigated within-category semantic distance effects in the continuous naming paradigm with reaction times (RTs) and event-related potentials (ERPs). Cumulative semantic interference and ERP effects were observed only for closely related members of basic level categories with high feature overlap (e.g. apes: orangutan, chimpanzee), indicating that shared broad semantic category membership (e.g. animals: orangutan, donkey) without considerable semantic feature overlap is insufficient to induce semantic interference. ERP modulations were characterised by an enhanced P1 at about 100–150 ms, that may reflect early co-activation of visual-conceptual feature information, and a relative posterior positivity starting at about 250 ms that was positively correlated with RTs, reflecting lexical selection. Furthermore, a posterior negativity between 450 and 600 ms was observed and associated with semantic-lexical calibration processes. These findings suggest early conceptual and lexical loci of semantic interference and underline the importance of converging activation spread triggered by shared semantic features during speech planning.