Kie Zuraw (UCLA) will be visiting the department this week. She will give the department colloquium on Friday, February 27, at 3:30 in N400. A title of her abstract follows.
The normal distribution--the bell curve--is common in all kinds of data, and is often expected when the quantity being measured results from multiple independent factors. The distribution of phonologically varying words, however, is sharply non-normal in the cases examined in this talk (from English, French, Hungarian,Tagalog, and Samoan). Instead of most words' showing some medial rate of variation (say, 50% of a word's tokens are regular and 50% irregular), with smaller numbers of words having extreme behavior, words cluster at the extremes of behavior--that is, a histogram of exceptionality rates is shaped like a U (or sometimes J) rather than a bell. The U shape cannot be accounted for by positing a binary distinction with some amount of noise over tokens, because some items (though the minority) clearly are variable, even speaker-internally. In some cases (e.g., French "aspirated" words) there is a diachronic explanation: sound change caused some words to become exceptional, so that the starting point for today's situation was already U-shaped. But in other cases, such an explanation is not available, and items seem to be attracted towards extreme behavior.
Two mechanisms for deriving U-shaped distributions will be presented, with some speculation as to why some distributions of variation are U-shaped and others bell-shaped.