According to accommodation theory, there are two main strategies: convergence and divergence. Convergence occurs when the speaker adjusts his or her normal speech to make it more similar to the interlocutor’s speech or when the speaker converges toward a prestigious norm that he or she believes is favored by the interlocutor. In short, the speaker accepts the interlocutor’s values and seeks to demonstrate that acceptance by his or her own linguistic behavior.
Conversely, divergence occurs when speakers seek to alter their speech in order to make themselves linguistically different. Both convergence and divergence can take place in an upward or downward fashion. Upward convergence occurs when speakers adjust their speech to exhibit the norms of high-status individuals in their society. Downward convergence involves adjustments in the direction of the speech norms from a higher class to a lower class.
For instance, a person with a PhD in physics will speak differently when explaining quantum mechanics to a high school dropout than when discussing physics with colleagues; that is, the physicist will use language in a manner designed to simplify complex concepts for his or her less educated interlocutor. Generally, upward convergence is the more common type because it is based on the universal desire for approval from those we respect and emulate.
Upward divergence occurs when speakers emphasize the standard features of their speech, whereas downward divergence occurs when speakers emphasize the nonstandard features of their speech. An example of upward divergence would be two people from different classes arguing, with the individual from a higher-socioeconomic background emphasizing the standard features of his or her speech to distinguish himself or herself from the lower-class interlocutor. In the same example, the person of lower-socioeconomic status who emphasizes his or her less standard form of speech would be exhibiting downward divergence.
The causes of convergence and divergence can be complicated. One of the most well-known studies regarding accommodation theory was initiated by Giles and his colleagues. It concerned conversations between unequally ranked nurses and how convergence and divergence operated on the basis of their ability to use the English language. The results showed that when speaking to lower-ranked nurses, those with a higher status used a less standard English; likewise, when the lower-status nurses spoke to their higher-ranked colleagues, they spoke a more standard English.
Moreover, people are more likely to convert their speech rates in a manner emphasizing the stereotype of their interlocutors’ speech rates and their way of using language. In addition, speakers tend to switch from convergence to divergence as they reevaluate the person they speak to during the conversation.