A thesis submitted in partial fulfilment of - Queen Margaret University

epresentations as a function of word class was found in Tyler, Russell, Fadili
and Moss’ (2001) PET scan investigation with healthy people. They did report
however that verbs with inflections were more difficult to retrieve than nouns with
inflections. Dissociations between proper and common nouns following brain
damage have also frequently been reported, questioning if the different word
classes are processed by distinct mechanisms (Robson, Marshall, Pring and
Montagu, 2004). It is generally agreed that proper nouns are processed
differently both neuropsychologically and anatomically than common nouns in
the brain with proper nouns being considered to be labels attached to referents
and thus without semantic meaning (Schmidt, Buchanan and Semenza, 2004;
Yasuda, Nakamura and Beckman, 2000; Lyons, Hanley and Kay, 2002; Miceli,
Capasso, Daniele, Esposito, Magarelli and Tomaiuolo, 2000). Robson et al.
(2004) report that the production of proper nouns were significantly more difficult
to name than common nouns but the comprehension of both word classes were
high with no class effect.
2.8.4 Summary and implications
The above brief description of the representations of vocabulary indicates some
controversy in the interpretation of evidence for the number of lexical and
semantic systems as well as the behaviour of different word classes. This
investigation will assume the existence of four lexicons – one for listening,
reading, speaking and writing in accordance with the cognitive
neuropsychological approach (Ellis and Young, 1996; Kay et al., 1992). There
appears to be more evidence and support for a unimodal semantic system
where all modalities access the meaning and associations of words (for example
Capitani et al., 2003; Caramazza et al., 1990; Hillis et al., 1990). Therefore this
investigation will assume the existence of one central semantic system relating
to the cognitive neuropsychological model (Ellis and Young, 1996; Kay et al.,
1992). Controversy also exists for the behaviour and location of word class with
verbs being considered more difficult to process than nouns by some
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