The values, beliefs and principles underlying a conceptual model have a major influence on its identity and development. The assumptions underlying the Occupational Performance Model (Australia) fall into three broad categories: assumptions about human occupations, assumptions about human performance and assumptions about humans as self-organising systems.

Human Occupations

Assumptions about human occupations are derived from core philosophical tenets of occupational therapy which have been described by others (see for example: Canadian Association of Occupational Therapy, 1991; Christiansen, 1991; Hopkins, 1993, Keilhofner, 1995; Meyer, 1922/1977; Reed, 1984, 1993; Rogers, 1982). People are viewed from an wholistic perspective as being comprised of interacting elements of mind, body and spirit. Engagement in occupation provides a sense of reality, mastery, competence, autonomy and temporal organisation. Engagement in occupation involves an interaction between people and their environment. Health is not the absence of disease; rather it is competence and satisfaction in the performance of occupational roles, routines and tasks. Humans are active in the process of creating their occupational being or identity. This active participation can be intrinsically driven by choice or need, or externally imposed by environmental factors. An occupational being is that aspect of a human being that ideates and actualises engagement in occupational roles. This occupational being is expressed through occupational performance and ultimately defined by peoples’ occupational roles. Occupational Performance Model (Australia) 3

Performance

The term, ‘performance’, is usually assumed to mean action or motor performance: often the end product of other mental or psychological processes (Keilhofner, 1995; Nelson, 1988). The assumption underlying the model presented in this paper is that performance is more than ‘doing’. Delbridge (1981, p.1285) not only defines ‘performance’ as execution or doing, but more broadly defines performance as the way in which someone reacts under certain conditions, or fulfills a purpose. A reaction can be a physical, mental or emotional change. Purpose implies desire or motivation (Delbridge, 1981, p.722). ‘Performance’ in this model is therefore assumed to go beyond ‘doing’ to incorporate ‘knowing’ and ‘being’.

Self-Organisation

Humans are assumed to be self-organising systems that produce patterns of behaviour arising from the cooperative interaction of many elements (Kelso, Mandell & Schelsinger, 1989; Schöner & Kelso, 1988). This self-organisation is not necessarily explained by conceptual models of input-output mechanisms but rather by dynamic or non-linear systems. The underlying assumption of a dynamic view of behaviour is that humans are made up of a number of complex, multidimensional subsystems. No one subsystem has logical priority for organising or initiating the behaviour of the system. This assumption means that occupational behaviour at any one time occurs in response to the confluence of all the constructs outlined in the model, and that small changes in any one of the constructs can have major overall effects.