Since the notion of semantic-pragmatic disorder (SPD) was first described (Rapin, 1982) there has been much discussion about its characteristic features. Diagnostic criteria have still to be agreed. There has also been much debate about the psychological mechanisms that underlie SPD, particularly in relation to speculation about the boundaries of SPD with autism and specific language impairment (SLI). Discussion has focused on whether SPD has cognitive, socio-cognitive or linguistic underpinnings.
In view of the above, the present study had two main aims: (1) to clarify the issue of diagnostic criteria by obtaining comprehensive behavioural profiles of a group of children, of a similar age, identified as presenting with SPD and (2) to provide preliminary evidence concerning the possible underlying psychological mechanisms of executive dysfunction, weak: central coherence and impaired world knowledge in this group, in relation to normal and specifically language-impaired controls. A third aim was to provide further evidence concerning the suggestion that SPD results from impaired theory of mind.
Regarding the first aim, a number of common features in linguistic, conversational, intellectual and social functioning emerged. In line with the findings from several other recent studies (Conti-Ramsden et al., 1997, 1999), this would suggest that SPD constitutes a definable clinical entity. However, there were some inconsistencies between this study and other studies in the characteristic features that occurred. The clinical implications of these findings are considered.
Regarding the second and third aims, there were no significant differences between the three groups on the world knowledge tasks, failing to support the suggestion that SPD might stem from a lack of world knowledge (McTear, 1989; Bishop & Adams, 1992). In addition, there were few significant differences between the three groups in theory of mind, executive function and central coherence, all of which have been implicated in autism. These findings are discussed in relation to the issues of boundaries between SPD, SLI and autism.