Competitor Activation and Semantic Interference: Evidence from Combined Phonological and Semantic Similarity.

Incremental learning explanations state that semantic interference is driven by activation levels of competitors. To explore nonsemantic contributions to interference, we examined the combined and separate effects of facilitatory phonological form preparation and semantic relatedness in a blocked cyclic picture naming procedure. Phonological similarity was facilitatory when tested separately, but had little effect when tested with the other conditions. We found about twice as much interference in word sets that shared both meaning and form (e.g., cyclically name puffin, pigeon, and peacock) as in semantic-only sets. Thus, phonological similarity impacted interference when it was combined with a semantic attribute. A computational model that isolated the learning mechanism and eliminated carryover effects simulated this result and additionally showed cumulative interference over naming cycles. Together with other findings from our research group and in the literature, these results suggest that co-activation from a variety of sources can drive interference.