The Bias Toward Single-Unit Turns in Conversation

ABSTRACT Sacks, Schegloff, and Jefferson argued that the rules for turn taking for conversation involve a confluence of pressures that bias turn size toward single turn constructional units (TCUs), which leads to an empirical prediction that turns are more likely to be composed of single (vs. multiple) TCUs. We directly test and confirm this “single-TCU bias” by using conversation analysis, corpus linguistics, and Bayesian statistics to assess the conversational subcorpus of the British National Corpus (BNC-C), which contains 475,509 turns of talk. Our results confirm this bias, showing that 67% of turns are composed of single TCUs; we discuss why this estimate is conservative. The mean word length for single-TCU turns was 4.5 (SD = 3.4), compared to 19.9 (SD = 22.6) for multi-TCU turns. Our findings reinforce the ideas that the natural habitat for an accountable social action is the single TCU (vs. the turn), and that interaction is fundamentally organized (i.e., both produced and understood) on an action-by-action basis, which is a TCU-by-TCU basis. Data are in British English.