Electrophysiological Evidence for Sentence Comprehension - Wings

well known that SLI children do not constitute a homogenous group. Language abilities
were also compared across different populations to establish similarities and
dissimilarities in language function between children with SLI and e.g. Autism or Down
Syndrom (Bishop & Frazier-Norbury, 2002; Laws & Bishop, 2003) with a different
rationale: to show how some non-linguistic deficit (in these articles ‘general information
processing’) affects language function in a similar fashion in different deficits exactly
because the underlying deficit in SLI is more general and not language specific. Similar
approach is adopted in the ‘critical mass’ approach of Conti-Ramsden & Jones (1997).
The lexicon limitations simply do not allow children with SLI to make rules, i.e. it is due
to the general learning mechanism failure that the children need bigger vocabulary to
extract rules; therefore, morphology (especially verb morphology) is affected although
the core of the deficit lies somewhere else.
Heterogeneity of SLI is notorious (although for opposite view see e.g. Schöler & Fromm,
1996). However, there is even less agreement about the classification of subgroups of SLI
than about its definition. Reviewing the literature Fletcher (1992) suggests three criteria
for classification: clinical, psychometric and linguistic. Other researchers usually
confront two criteria, clinical and psychometric (e.g. Conti-Ramsden & Adams, 1995,
Conti-Ramsden et al., 1997, Leonard, 1998). As the names imply, psychometric (or
‘cluster analysis’) criteria define subgroups based on different outcomes on various
language and non-language tests. The tests usually cover articulation, receptive and
expressive vocabulary and aspects of receptive and expressive grammar. Word and non-
word repetition as well as sentence repetition is often included. Recently, narrative tests
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