Concealing one's meaning from overhearers

Abstract

Two people talking, as at a crowded party, may try to conceal all or part of what they mean from overhearers. To do this, it is proposed, they need to build what they wish to conceal on a private key, a piece of information, such as an event mentioned in an earlier conversation, that is common ground for the two of them and yet not inferable by the overhearers. What they say must be designed so that it cannot be understood without knowledge of that key. As evidence for the proposal, pairs of friends were required, as part of an arrangement task, to refer to familiar landmarks while concealing these references from overhearers. As predicted, the two of them used private keys, which they often concealed even further by using certain collaborative techniques. Still, the two partners weren't always successul.