The mixed truth about frequency effects on free recall: effects of study list composition.

The mixed-list paradox is the finding that high-frequency words show a recall advantage in blocked lists, but that this advantage is reversed or nullified in mixed lists. We argue that this paradox has been poorly defined. Specifically, researchers should investigate random and alternating lists separately. We examine blocked, random, and alternating lists in our experiment. We hypothesize that a low-frequency recall advantage could arise due to asymmetrically strong links between low- and high-frequency words. Supporting our hypothesis, a low-frequency recall advantage is observed in the random list, as is an asymmetry of association. In the alternating list, no recall advantage is observed, and neither is any asymmetry of association. Our results offer a clear challenge to future research to (1) consider the associations between word frequencies and (2) consider random and alternating lists separately.