College students rated verbal items for either familiarity or meaningfulness and were then tested for their recognition memory of rated items from four critical classes: nonwords and words appearing less than 1 time, 1-10, and more than 40 times per million words of written text (Thorndike-Lorge, 1944). Following either rating task, recognition errors were found to be a Ll-shaped function of word frequency and nonwords were recognized least well. Although a Ll-shaped function was expected on the basis of what is known about word frequency effects in general, there is significant disagreement as to the mechanism(s) responsible for this relationship.Memory for low-frequency~LF) words is generally superior to that for high-frequency (HF) words when recognition is tested. This word frequency effect (WFE) is quite reliable, having been shown, for example , for both written and aural presentation , with paced and unpaced study, and in absolute-judgment as well as in forced-choice testing procedures (Schulman, 1967;Shepard, 1967; Underwood & Freund, 1970). However, notably missing among studies investigating the WFE is any systematic manipulation of word frequency across a wide range of frequencies, the WFE typically being reported when recognition for words of only two rather disparate levels of background frequency has been tested . Yet, there is speculation that probability of correct recognition is an "inverted-U-shaped" (Schulman , 1976, p. 307) or "curvilinear" (Gregg, 1976 function of frequency , were recognition to be examined over the complete range of word frequencies .Schulman (1976) reached this conclusion after observing college students' recognition memory for very rare words they previously had rated for familiarity . He found that probability of correct recognition increased with an item's rated familiarity , showing a "reversal" of the usual WFE. As noted, generally only two classes of words are used to show the typical WFE and, since these items almost always can be described as "very familiar" and "relatively unfamiliar" (but not totally unfamiliar), on the basis of his results Schulman reasonably predicted that probability of correct recognition should first increase and then decrease as familiarity (frequency) increased.Gregg (1976) also suggests a nonmonotonic relationship between recognition probability and background frequency. He points to the findings of Allen and Garton (1968), who "manipulated" word familiarityRequests for reprints should be addressed to Eugene B. Zechmeister, Department of Psychology, Loyola University of Chicago, 6525 North Sheridan Road, Chicago, l1linois 60626 .by having physics and arts students view both physics and common words. Overall, physics words were recognized better than common words, demonstrating the WFE. However, physics students recognized physics words better than did arts students, while there was little difference between the two groups of students when common words were tested. If we think of the arts student studying physics words as somehow similar...