Language is about communication. It can be studied as written sentences, as production of spoken language, or as comprehension of spoken language, but these do not get to the heart of communicating. Language evolved as conversation, each baby learns it in conversation and most of our use of it each day is in conversations. Exchanges, taking turns, is the essence of language. A recent paper by S. Levinson in Trends in Cognitive Sciences, “Turn-taking in Human Communication – Origins and Implications for Language Processing”, looks at the complications of turn-taking.
The world’s languages vary in almost all levels of organization but there is a striking similarity in exchanges – rapid turns of short phrases or clauses within single sound envelopes. There are few long gaps or much overlapping speech during the changes of speaker. Not only is a standard turn-taking universal in human cultures but it is found in all types of primates and it is learned by babies before any language is acquired. It may be the oldest aspect of our language.
But it is paradoxical – for the gap between speakers is too short to produce a response to what has been said by the last speaker. In fact, the gap tends to be close to the minimum reflex time. A conversational speaking turn averages 2 seconds (2000ms) and the gap between speakers is about 200ms, but it takes 600ms to prepare the first word (1500ms for a short phrase). So it is clear that production and comprehension must go on at the same time in the same areas of the brain and that comprehension must include a good deal of prediction of how a phrase is going to end. Because comprehension and production have been studied separately, it is not clear how this multitasking, if that is what it is, is accomplished. First, the listener has to figure out what sort of utterance the speaker is making – statement, question, command or whatever. Without this the listener does not know what sort of reply is appropriate. The listener then must predict (guess) the rest of the utterance, decide what the response should be and formulate it. Finally the listener must recognize the signal/s of when the end of the utterance will be. The listener can immediately begin to talk as soon as the utterance ends. There is more to learn about how the brain does this and what the effect of turn-taking has on the nature of language.
There are cultural conventions that override turn-taking so that speakers can talk for some time without interruption, and even if they pause from time to time, no one jumps in. Of course, if someone speaks for too long without implicit permission, they will be forcibly interrupted fairly soon, people will drift away or some will start new conversations in sub-groups. That’s communication.
Here is the abstract of - Stephen C. Levinson. Turn-taking in Human Communication – Origins and Implications for Language Processing. Trends in Cognitive Sciences, 2015:
“Most language usage is interactive, involving rapid turn-taking. The turn-taking system has a number of striking properties: turns are short and responses are remarkably rapid, but turns are of varying length and often of very complex construction such that the underlying cognitive processing is highly compressed. Although neglected in cognitive science, the system has deep implications for language processing and acquisition that are only now becoming clear. Appearing earlier in ontogeny than linguistic competence, it is also found across all the major primate clades. This suggests a possible phylogenetic continuity, which may provide key insights into language evolution.
The bulk of language usage is conversational, involving rapid exchange of turns. New information about the turn-taking system shows that this transition between speakers is generally more than threefold faster than language encoding. To maintain this pace of switching, participants must predict the content and timing of the incoming turn and begin language encoding as soon as possible, even while still processing the incoming turn. This intensive cognitive processing has been largely ignored by the language sciences because psycholinguistics has studied language production and comprehension separately from dialog.
This fast pace holds across languages, and across modalities as in sign language. It is also evident in early infancy in ‘proto-conversation’ before infants control language. Turn-taking or ‘duetting’ has been observed in many other species and is found across all the major clades of the primate order.”