Semantic relations as graded concepts.

This experiment tests the hypothesis that semantic relations are graded concepts. It also tests the predictions of relation element theory and of Klix's (1986) theory of semantic relations regarding possible predictors of graded structure for semantic relations. Results support the hypothesis that semantic relations have graded structures, and indicate that differences among relations in gradedness reflect the families of semantic relations described by Chaffin & Herrmann (1984). In addition, Klix's distinction between property relations and event relations appears to be useful in explaining differences among relations in graded structure.