The shape of things to come in speech production: Visual form interference during lexical access

Naming a picture is slower in categorically related compared with unrelated contexts, an effect termed semantic interference. This effect has informed the development of all contemporary models of lexical access in speech production. However, category members typically share visual features, so semantic interference might in part reflect this confound. Surprisingly, little work has addressed this issue, and the relative absence of evidence for visual form interference has been proposed to be problematic for production models implementing competitive lexical selection mechanisms. In a series of five experiments using two different naming paradigms, we demonstrate a reliable visual form interference effect in the absence of a category relation and show the effect is more likely to originate during lexical or later response selection than during perceptual/conceptual processing. We conclude visual form interference in naming is a significant complicating factor for studies of semantic interference effects and discuss the implications for current accounts of lexical access in spoken word production.