Order Effects and Vowel Decay in Short-term Memory: the Neutralization Hypothesis

Information stored in short-term memory decays extremely fast compared to the content of long-term memory. The nature of this memory loss being little known (random or systematic), this paper examines the presentation order effect in the light of the neutralization hypothesis, according to which the first vowel in a pair decays toward [@], while retained in short-term memory. Twelve French listeners participated in three AX roving discrimination sessions. For each of the 10 vowel categories of French, a prototype and four satellite tokens were synthesized. Tokens were paired with themselves as well as with the prototype (in both orders of presentation). Results revealed minor or major order effects within every phonetic category. However, the neutralization hypothesis could not account for more than 50% of these asymmetries. An alternative model adopting the periphery of the vowel space as a reference area, appears to fit best with our data.