Conducted 5 reaction time (RT) experiments with 75 undergraduates to explore word-frequency effects in word-nonword decision tasks and in pronunciation and memory tasks. High-frequency words were recognized substantially faster than low-frequency words in the word-nonword decision tasks. However, there was little effect of word frequency in the pronunciation and old-new memory tasks. Further, in the word-nonword lexical decision task, prior presentations of words produced substantial and apparently long-lasting reductions on the basic frequency effect. The occurrence of natural language frequency effects only in the word-nonword decision task supported the use of this task to study the organization of and retrieval from the subjective lexicon. The modification of frequency effects by repetition suggested that natural language frequency effects may be attributed partly to the recency with which words have occurred. Analysis of the response latencies using S. Sternberg's (see record 1970-11748-001) additive-factors approach indicated that frequency effects consist of both effects in encoding and in retrieval from memory. (34 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)