In an ordinary interaction, communicants have various, mostly unconscious goals which reflect their interactional, social and personal needs. In these interactions, people’s minds try to find a balance between reaching these goals and consuming cognitive energy. If a speaker puts too little effort into speech production, she risks not achieving her communicative goals. This is especially typical when the atmosphere is relaxed, a good example of which is family discourse. An analysis of recorded conversations shows that there are certain regular (...) manifestations of risk-taking in family discourse, such as expressing immature thoughts, raising a large variety of topics and overguessing. A substantial amount of risk-taking in family discourse is in one way or another connected with false confidence in the interlocutors’ common ground. Family members know each other well, which results in an overestimation of the similarity of their understanding of words and objects. This attitude leads them to use cryptic, hard-to-comprehend speech. Quick, everyday interactions are mostly automated, and the speakers do not recognise that their speech is full of implicitness and underdeterminacy. (shrink)