In the word-length effect (WLE), lists of shorter words are better recalled than lists of longer words. This effect is fundamental to decay-based theories of verbal short-term memory,: such as the phonological loop theory (Baddeley, 1986). The WLE has been attributed to the time taken to articulate, words, not their structure, a critical point in the debate between decay and interference theories. However, word duration and complexity have previously been confounded. In this article, Mle show that the traditional WLE comprises two opposed effects: an advantage for words spoken more quickly (short words in terms of duration) and an advantage for words with more elements (long words in terms of complexity). We also report two interactions: a disadvantage for a midlist change in duration and an advantage for a midlist change in complexity. These results contradict simple decay-based theories and establish the importance of interference in short term memory. We discuss whether decay is also required.
