Adjacency Pair (Conversation Analysis)

In conversation analysis, an adjacency pair is a two-part exchange in which the second utterance is functionally dependent on the first, as exhibited in conventional greetings, invitations, and requests. It is also known as the concept of nextness. Each pair is spoken by a different person. 

In their book "Conversation: From Description to Pedagogy," authors Scott Thornbury and Diana Slade thusly explained the characteristics of the pair components and the contexts where they occur:

"One of the most significant contributions of CA [conversation analysis] is the concept of the adjacency pair. An adjacency pair is composed of two turns produced by different speakers which are placed adjacently and where the second utterance is identified as related to the first. Adjacency pairs include such exchanges as question/answer; complaint/denial; offer/accept; request/grant; compliment/rejection; challenge/rejection, and instruct/receipt. Adjacency pairs typically have three characteristics:
-they consist of two utterances;
-the utterances are adjacent, that is the first immediately follows the second; and
-different speakers produce each utterance"
(Cambridge University Press, 2006)

Having an adjacency pair is a type of turn-taking. It is generally considered the smallest unit of conversational exchange, as one sentence doesn't make for many conversations. What is in the first part of the pair determines what needs to be in the second part. Author Emanuel A. Schegloff illustrated the different pair types in "Sequence Organization in Interaction: A Primer in Conversation Analysis I":

"To compose an adjacency pair, the FPP [first pair part] and SPP [second pair part] come from the same pair type. Consider such FPPs as 'Hello,' or 'Do you know what time it is?,' or 'Would you like a cup of coffee?' and such SPPs as 'Hi,' or 'Four o'clock,' or 'No, thanks.' Parties to talk-in-interaction do not just pick some SPP to respond to an FPP; that would yield such absurdities as 'Hello,' 'No, thanks,' or 'Would you like a cup of coffee?,' 'Hi.' The components of adjacency pairs are 'typologized' not only into first and second pair parts, but into the pair types which they can partially compose: greeting-greeting ("hello,' 'Hi"), question-answer ("Do you know what time it is?', 'Four o'clock'), offer-accept/decline ('Would you like a cup of coffee?', 'No, thanks,' if it is declined)."
(Cambridge University Press, 2007)

Silence, such as a look of confusion on the receiver's part, does not count as part of an adjacency pair, as to be a component of such a pair, something must be uttered on the receiver's part. The attributable silence causes the speaker to rephrase the statement or continue until the second part of the pair—that which is spoken by the receiver—happens. So, technically, in normal conversation, the parts of the pair might not be directly adjacent to each other. Conversations can always also take sidetracks. Questions asked as a follow-up to questions can also split apart adjacency pairs, as the answer to the first has to wait until the follow-up question is answered. The important thing to remember when looking for the second part of the pair is that the response part is directly related to or caused by the first.

Background and Further Study

The concept of adjacency pairs, as well as the term itself, was introduced by sociologists Emanuel A. Schegloff and Harvey Sacks in 1973 ("Opening Up Closings" in "Semiotica"). Linguistics, or the study of language, has subfields, including pragmatics, which is the study of language and how it is used in social contexts. Sociolinguistics, which studies the relationship between society and language, is a subfield of both linguistics and sociology. Studying conversation is a part of all of these fields.