A final study presented here by Buchholz and his linguistic co-workers from the Freiburg Institute of Advanced Studies (FRIAS) focuses on another phenomenon: while we talk, it is always the case that many, many things remain unspoken. The simple fact of conversation silences them. Conversation is a selection. This was the Freudian starting point for inventing the "basic rule": to tell everything that comes to mind. However, it is well known that this task cannot be fulfilled. What can be studied is what Harvey Sacks named "noticeable absence" – if you are greeted and do not respond, this absence of an expectable response is noticed. The material studied here is a video-recording of a couple in trouble looking for therapeutic help. A ten-minute segment is analyzed, and it is shown how both participants omit essential conversational requirements. This can be realized by scientific observers who, at the same time, observe that the participants do not. The study uses various theoretical approaches that became necessary as the phenomena under study could not be understood with one theoretical frame of reference only. However, to our knowledge, it is the first empirically transcribed and video-analyzed interactional sequence of what clinicians would call a “collusion” (Dicks, 1967).