Shared Features Dominate The Number-Of-Features Effect

When asked to list semantic features for concrete concepts, participants list many features for some concepts and few for others. Concepts with many semantic features have been reported to be processed faster in lexical decision, naming, and semantic decision tasks (Pexman, Holyk, & Monfils, 2003; Pexman, Lupker, & Hino, 2002). Using a much larger and better controlled set of items in Experiment 1, we replicated the number-of-features (NoF) effect in both lexical and semantic decision. We then investigated the relationship between NoF and feature type (shared vs. distinctive). Shared features are those which appear in many concepts () whereas distinctive features appear in few concepts (). Keeping total NoF constant, decision latencies were shorter for concepts with many shared features versus those with few shared features in lexical and semantic decision, with a larger difference obtaining in semantic decision (Experiment 2). Manipulating shared or distinctive features to create low versus high levels of NoF revealed a much larger NoF advantage for concepts with many shared features than for those with many distinctive features (Experiment 3). It is concluded that shared features play a dominant role in the NoF effect.