The single-word semantic priming paradigm is a tool for investigating how and when word meaning activation occurs during visual word recognition. The prime task effect refers to the elimination of the typically robust semantic priming effect by a nonsemantic prime task . The purpose of this paper is to provide a tutorial review of the literature examining the prime task effect. Understanding the nature of this effect has implications for delineating how selective attention modulates evidence for semantic activation during word (...) reading. These implications are outlined. Additionally, speculations for how these issues of selective attention relate to awareness are offered. (shrink)