Chapter 5 compares the phraseology of usage to exposure. It shows that more than half of patterns extracted from a student’s usage corpus also occur in her exposure corpus. At the same time the figure drops significantly if these patterns are compared to a different student’s exposure corpus supporting the assumption of representativeness. The chapter then proceeds to compare usage patterns to exposure qualitatively focusing on the processes of variation and change. It finds support for the process of approximation through which a more or less fixed pattern loosens and becomes variable on the semantic or grammatical axis presumably due to frequency effects and the properties of human memory. The chapter also proposes a reverse process, fixing, through which the pattern extends and develops verbatim associations through repeated usage. Both processes are suggested to occur within meaning-shifts units and thus be characteristic of co-selection.

Chapter 7 summarizes the findings and offers a bigger picture with regard to (1) the idiom principle in L2 acquisition and use, (2) the model of a unit of meaning and (3) the processes behind the phraseological tendency of language. It argues that the idiom principle is available to L2 users to a larger degree than is often thought. It then proposes an ‘atomic’ model of a unit of meaning, shows how the processes of fixing and approximation fit into the larger processes of delexicalization and meaning-shift, further develops the idea of a continuum of delexicalization suggested in Chapter 2 as well as explains the connection between these ideas and the concepts of relexicalization and re-metaphorization. The chapter ends with a discussion of limitations and promising directions of future research.