Chromatic and anisotropic cross-recurrence quantification analysis of interpersonal behavior

Cross-recurrence quantification analysis (CRQA) is a powerful nonlinear time-series method to study coordination and cooperation between people. This chapter concentrates on two methodological issues related to CRQA on categorical data streams, which are commonly encountered in the behavioral sciences. Firstly, we introduce a more general definition of recurrence as ‘behavioural matching’, which can be applied to several kinds of matches simultaneously, visualized by a colour coding. We will refer to this as cross-matching, and to the resulting quantification procedure as Chromatic CRQA. Secondly, cross-recurrence plots of categorical data often prominently consists of rectangular structures. This calls for a differential analysis of vertical and horizontal lines, rather than of diagonal lines. We introduce a simple procedure for this, referred to as Anisotropic CRQA. Both procedures are demonstrated with empirical studies on children’s problem-solving behaviour and by means of a model simulation. The authors hope that the ideas presented here increase the power and applicability of CRQA in the behavioural sciences, and that this chapter serves as a stepping stone for their mathematical and methodological development