Approaches to assessment which take account of the issues discussed in the previous chapter will need to address a number of factors. Firstly, adopting a functional perspective implies that a key task of assessment will be to identify the behavioural (and other) processes responsible for maintaining the person's challenging behaviours. This process will be referred to as functional assessment. Secondly, taking a constructional approach to intervention suggests that it will be necessary to evaluate aspects of the individual's existing repertoire and to identify potential reinforcers which may be employed in establishing new behaviours. Finally, the requirement that interventions be ethical and socially valid indicates the need to evaluate the feasibility and potential risks, costs and benefits of the intervention process.

Functional assessment

In recent years, a number of reviews and practical guides have focussed on the procedures and techniques which may be involved in functional assessment (e.g. Carr et al., 1994; Demchak & Bossert, 1996; Durand, 1990; Feldman & Griffiths, 1997; Halle & Spradlin 1993; Lalli & Goh, 1993; McBrien & Felce, 1994; Meyer & Evans, 1989; Miltenberger, 1998; O'Neill et al., 1997; Pyles & Bailey, 1990; Romanczyk & Matthews, 1998; Vollmer & Van Camp, 1998; Wacker et al., 1998; Zarkowska & Clements, 1994). In the following sections, some of the key issues and important trends in this burgeoning area will be discussed.