This proposed study will examine the underlying causalities of the U-shaped developmental trend in metaphoric production and the causes which make up the linearly increasing trend. Seven hypotheses will be tested in the study. Ninety children, all from middle-class families and attending nursery and public schools in Austin (Texas), with ages ranging from 3-14 years, will participate as subjects. Children will participate in three tasks regarding metaphoric production, two knowing-level tasks, and the Peabody Picture Vocabulary Test. Metaphoric figures will be rated by trained judges and the number of figures transformed into proportion. The model predicts the relationship between metaphoric production, age, and vocabulary capacity. The proposed study argues that knowing-level is the underlying causality for the U-shaped curve and that age is a covariate with knowing-level. Further studies are suggested for creating a better method for encoding the individual's novel and frozen metaphors, employing a cross-cultural design, investigating the U-shaped developmental curve in other creative fields and in subjects who are deficient in some major fields, and exploring the relationship between knowing-level two and metalinguistic abilities in regard to the relationship between linguistic and cognitive development. (One table of data and five figures are included. Forty-nine references are attached.) (MG)