The "Decimal System", a Principle- and Function-Based Classification for Behaviour Assets and Problems, and Related ecological and Biological Factors (2nd ed.)

The Decimal System of Behaviour and Life (DSBL) Assets and Problems (Tuomisto, 2014) is a conceptual, systematic, behaviour chain-based and functional framework or algorithm for the classification of behaviour and life problems. It is part of the process-based movement in clinical and applied science (see, e.g., Hayes & Hofmann, 2020). The system categories are on the one hand principle-based topographic behaviour chains or on the other functional classes of existing/lacking or adaptive/non-adaptive behaviours or behavioural contingencies defined in behaviour analytic terms. This system has category borders yielding mutually exclusive main categories in seven of the main categories. The system enables the classification of primary problems and problems that are functions of these, that is, secondary or subsequent problems. Establishing the order of importance of the target behaviours or behaviour deficits in links of behavioural instances in chains and concurrent behavioural chains competing or influencing each other renders possible a response to the question: Which behaviours to target first? The primacy of a problem is partly dependent on coherent-pragmatic goals. Sometimes practical or experimental tests are the only means to determine if an issue would be classified as a problem, although other methods such as descriptive behaviour assessment, frequently suffice or are the only option. Chain analyses of behaviours allow the analysis of primary-secondary behaviours or behaviours earlier or later in a chain. The DSBL enables tailoring individual treatments according to the goals derived from the system. The system is based on behavioural processes that also make problem identification possible “on-line” or in vivo. The most general criterion of the validity of the system is this: Does it make effective action feasible in a problem situation? This text is the first full presentation of the system in English as a separate publication in book form.