Backchannel choices affect conversational development. Some backchannels invite interlocutors to continue to the next part of what they are saying and others invite them to elaborate on what they have just said. We tested how communicative modality (audiovisual, audio, text), environmental setting (wholly in-lab, partially in the wild), and conversational goals (on-task, off-task) influenced backchannel usage by participants. We found that backchannel production depends on modality, setting, and goals. For example, we found that specific backchannels played a more prominent role (...) in self-motivated dialogue. Knowledge of how backchannels are used has both theoretical and practical implications. (shrink)