By definition, a pair of inherently unmeasurable, non-stationary systems, are coupled to produce an inherently measurable stationary system. - Gordon Pask

An earlier paper (Pask, 1976) introduced conversational techniques, some involving a human participant in dialogue with a student, others involving a mechanically or computer implemented 'participant' through which the student 'talks to himself' under restrictions imposed by the device. In either case (human or mechanical monitoring) the subject matter of a conversation is represented in a liberally conceived, but standard, fashion, as a conversational domain consisting in an entailment structure (embodying one or more description schemes and indicating the many ways in which one topic may be known in terms of or derived from others) and behaviour graphs (one for each topic in the domain) that prescribe what may be done to model or explain the topic in question. Within this framework, the conversational techniques secure, or approximate, a standard condition for experiments on learning.

We now come to the underpinning contention of the previous monograph. Psychological phenomena, especially those involved in learning and education, stem from or are related to states of consciousness. Using the argument which relates the information available about conscious processes to the type of experimental situation, we maintain that the basic unit of psychological /educational observation is a conversation. In order to test hypotheses and explicate the conversational transactions, it is necessary to invoke various tools and explanatory constructs. These are coherent enough to count when interlocked as a theory, and this theory was dubbed conversation theory.

Since human beings are highly adaptable it may be possible for an individual with any sort of competence to learn, in the end, according to any teaching strategy. But the experiments show, very clearly indeed, that the rate, quality and durability of learning is crucially dependent upon whether or not the teaching strategy is of a sort that suits the individual