RT list: Relevance-based comprehension procedure

Dear all,
I have a rather basic question about Relevance Theory, but as it has
been tormenting me for a while, so I would be grateful if someone could
reply. I can't seem to be able to locate who first proposed the
relevance-based comprehension procedure, discussing it to some extent.
I have gone as far back as Sperber's 'Understanding Verbal
Understanding' (1994) where, discussing an example, he suggests that
"all John has to do now is follow the path of least effort in
constructing an interpretation of Carol's behaviour and stop when he
reaches an interpretation that provides him with information relevant
enough to be worth his attention". So far as this path for
comprehension was not included EXPLICITLY in the original book on
Relevance, and has escaped my attention, I cannot find its original
source. What I am interested in finding is an argumentation discussing
the path of least effort, i.e. that we entertain hypothesis in order of
accessibility, rather than the 'expectations of relevance' that guide
us to the intended interpretation. The path of least effort is
obviously and intuitively correct, however, I would like to see whether
this assumption is based on more concrete arguments about how we access
background information, rather than taken for granted as part of the
relevance-theoretic way of thinking. Thank you in advance for your time.

With regards,
Stavros

-- 
Stavros Assimakopoulos
PhD candidate
Department of Linguistics and English Language
University of Edinburgh