Introduction

All communication occurs in a network environment with the exception of a subset of systems that unequivocally meet both of the following criteria: (a) a signal can never be received by more than one receiver; (b) a receiver can never receive more than one signal simultaneously. In other words, all communication networks have at least one of two defining properties: (a) signals can be, at least potentially, received by several receivers; and (b) receivers can, at least potentially, receive signals from several signallers at any one time. Consequently, in moving from a dyadic consideration of communication to a network view, signallers and receivers both take on a range of costs and benefits, which are the theme of this book. In this chapter, I will consider the implications of a particular type of receiving behaviour that becomes possible in a network, namely eavesdropping. I will begin by reviewing different definitions of eavesdropping that are found in the literature and the evidence for different types of eavesdropping, distinguishing between eavesdropping on signals and eavesdropping on signal interactions. I will then examine the costs, benefits and implications of eavesdropping on interactions, as recognition of this phenomenon emerged from considerations of qualitative differences between dyadic and network views of communication (McGregor, 1993; McGregor & Dabelsteen, 1996).