Information statistics as applied to social interaction between mother and infant: synergic covariability vs. partial...

Behaviour can, in general, not be quantified on an equal-interval scale; therefore, the description of sequential aspects of the behaviour of two interacting individuals can not be formulated on the basis of the usual cross-correlation techniques. If the information content of behaviour, however, is defined analogously to the entropy in a message, this allows a quantification of the contribution of either participant to the interaction process, and the identification of a non-additive (synergic) component in addition to the auto- and cross-covariability terms. Such a framework, based on the concept of transinformation or mutual information, was developed and realised in a suite of three FORTRAN programs. These were then applied in a longitudinal study on the development of early mother-infant interaction. The synergic term appears to increase with age in the first five months of life. This application illustrates the usefulness of information statistics for quantifying the ways in which participants contribute to a process of interaction.