ABSTRACT
Underlying ACT is a behavioural theory of human language and cognition called relational frame theory (RFT). As RFT is relatively complex and space here is very limited, the speci®c technical components of RFT will not be discussed (instead, see Blackledge, 2003, for introductions to the theory, or Hayes, Barnes-Holmes, & Roche, 2001a, for an extended treatment). However, the essence of the theory and its relevance to ACT will be discussed. Radical behavioural accounts of human language and cognition (e.g. Skinner, 1957) proved not to be empirically viable (Hayes, Blackledge, & Barnes-Holmes, 2001b). Repeated laboratory experiments (some of which are discussed in Hayes et al., 2001b) that strongly suggested the verbal abilities of humans markedly compromised the ability of conventional behavioural theory (as exempli®ed by Skinner, 1974) to predict or control human behaviour (relative to nonhuman behaviour) were conducted from the 1970s onwards. RFT was developed by Steven Hayes and colleagues, beginning in the mid-1980s, as an attempt to preserve the strengths of conventional behavioural theory while parsimoniously extending its concepts to account for the peculiarities of human language and cognition.
