Turn construction unit
A turn construction unit (TCU) is the fundamental segment of speech in a conversation, as analyzed in conversation analysis.
The idea was introduced in (Sacks, Schegloff, & Jefferson 1974) and is meant to describe pieces of conversation which may comprise an entire turn. The end of a TCU, called a transition relevance place (TRP), marks a point where the turn may go to another speaker, or the present speaker may continue with another TCU.
Turn Construction Unit (TCU)
A Turn Construction Unit (TCU) is a building component of a turn in a conversation. It is a unit of conversation that completes a communicative act.
Types of TCU
There are four types of TCU categorized by the roles they play in the utterance:
1. Lexical TCU: e.g. "Yes", "There"
2. Phrasal TCU: e.g. "In the basket", "out of here"
3. Clausal TCU: e.g. "When I am free", "If I got the job"
4. Sentential TCU: e.g. "I am working on my thesis", "He has got my car"
Criteria for Turn Construction Unit
A general rule to identify a TCU would be to look for a possible completion in an ongoing utterance. There are three criteria to determine what constitutes a TCU:
1. Intonationally Complete: This means the utterance is at a possible point of completion with the hint of a falling tone, signaling the possible ending of the utterance.
2. Grammatically Complete: This means the utterance is at a possible point of completion with a hint of its syntactic completeness, i.e. it signals the end of a sentence in terms of its grammatical structure.
3. Pragmatically Complete: This means the utterance is seen to have possibly accomplished its purpose in response to the situation during a conversation. For example, the utterance "She is really" can be seen as pragmatically complete in response to the exclamation, "That girl is really pretty!", in the sense that it functions as an agreement to the previous comment.
Scholars in the field of conversation analysis have debated over the relative significance of the above three criteria as signifiers of the end of an utterance. There are, however, no conclusive answer to the discussion, and one can classify a TCU as such when observing either one (or more) of the above features.
Transition Relevance Place (TRP)
Transition Relevance Place (or TRP) is a point of possible completion (or potential end) of an utterance (hence a TCU) where speaker change is a possible next action.
References
Sacks H, Schegloff E A, Jefferson G. "A simplest systematics for the organization of turn-taking for conversation." Language 50 (1974) pp. 696–735