  Conversational participants tend to immediately and unconsciously adapt to
each other's language styles: a speaker will even adjust the number of articles
and other function words in their next utterance in response to the number in
their partner's immediately preceding utterance. This striking level of
coordination is thought to have arisen as a way to achieve social goals, such
as gaining approval or emphasizing difference in status. But has the adaptation
mechanism become so deeply embedded in the language-generation process as to
become a reflex? We argue that fictional dialogs offer a way to study this
question, since authors create the conversations but don't receive the social
benefits (rather, the imagined characters do). Indeed, we find significant
coordination across many families of function words in our large movie-script
corpus. We also report suggestive preliminary findings on the effects of gender
and other features; e.g., surprisingly, for articles, on average, characters
adapt more to females than to males.
