The effects of stimulus set size and word frequency on verbal serial recall

Two experiments are reported which examine immediate serial recall for high -and low-frequency words. The words in each list were either repeatedly dra wn from the same small pool of candidates (in the closed set conditions) or each word only ever occurred once during the experiment (in the open set c onditions). The results consistently show an effect of word frequency but t he effect of set size was only apparent for low-frequency words. It is argu ed that both frequency and set size effects reflect processes concerning th e "clean-up" of degraded short-term memory traces.