Wh-words sound similar to aid rapid turn taking

A new paper by Anita Slonimska and myself attempts to link global tendencies in the lexicon to constraints from turn taking in conversation.

Question words in English sound similar (who, why, where, what …), so much so that this class of words are often referred to as wh-words. This regularity exists in many languages, though the phonetic similarity differs, for example:

In her Master’s thesis, Anita suggested that these similarities help conversation flow smoothly.  Turn taking in conversation is surprisingly swift, with the usual gap between turns being only 200ms.  This is even more surprising when one considers that the amount of time it takes to retrieve, plan and begin pronouncing one word is 600ms.  Therefore, speakers must begin planning what they will say before current speaker has finished speaking (as demonstrated by many recent studies, e.g. Barthel et al., 2017). Starting your turn late can be interpreted as uncooperative, or lead to missing out on a chance to speak.

Perhaps the harshest environment for turn-taking is answering a content question.  Responders must understand the question, retrieve the answer, plan their utterance and begin speaking.  It makes sense to expect that cues would evolve to help responders recognise that a question is coming.  Indeed there are many paralinguistic cues, such as rising intonation (even at the beginning of sentences) and eye gaze.  Another obvious cue is question words, especially when they appear at the beginning of question sentences. Slonimska hypothesised that wh-words sound similar in order to provide an extra cue that a question is about to be asked, so that the speaker can begin preparing their turn early.

We tried to test this hypothesis, firstly by simply asking whether wh-words really do have a tendency to sound similar within languages.  We combined several lexical databases to produce a word list for 1000 concepts in 226 languages, including question words.  We found that question words are:

• More similar within languages than between languages
• More similar than other sets of words (e.g. pronouns)
• Often composed of salient phonemes

Of course, there are several possible confounds, such as languages being historically related, and many wh-words being derived from other wh-words within a language. We attempted to control for this using stratified permutation, excluding analysable forms, and comparing wh words to many other sets of words such as pronouns which are subject to the same processes.  Not all languages have similar-sounding wh-words, but across the whole database the tendancy was robust.

Another prediction is that the wh-word cues should be more useful if they appear at the beginning of question sentences.  We tested this using typological data on whether wh-words appear in initial position.  While the trend was in the right direction, the result was not significant when controlling for historical and areal relationships.

Despite this, we hope that our study shows that it is possible to connect constraints from turn taking to macro-level patterns across languages, and then test the link using large corpora and custom methods.

Anita will be presenting an experimental approach to this question at this year’s CogSci conference.  We show that /w,h/ is a good predictor of questions in real English conversations, and that people actually use /w,h/ to help predict that a question is coming up.

Slonimska, A., & Roberts, S. G. (2017). A case for systematic sound symbolism in pragmatics: Universals in wh-words. Journal of Pragmatics, 116, 1-20. Article.  PDF.

All data and scripts are available in this github repository.