Neural Correlates of Processing Syntax in Music and ... - PubMan

Specific Language Impairment 78
6.3 Risk factors
In general, the aetiology of SLI remains elusive, mainly due to a very heterogeneous
pattern of deficiencies. Currently, there is no well-accepted explanatory hypothesis the
account for the heterogeneous pattern of deficiencies in children with SLI, and several
hypotheses on possible causal factors for SLI exist in parallel. None of these hypotheses
can account for all characteristics of SLI.
Different disciplines are involved in the scientific research on the nature and the treatment
of SLI which may propose different explanations (cf. Ors et al., 2005; Tomblin,
Hafeman, & O'Brien, 2003). Moreover, there is a lack of agreement about which symptoms
should be regarded as characteristic for SLI (see, e.g., Dannenbauer, 2004). The
ambiguity of the definition is not only caused by the complexity of the characteristics of
SLI, but further by similar symptoms that may be accounted for by different conditions
and etiological factors.
Tomblin et al. (1997) introduced the term “risk factors” instead of causal factors (see
also Delgado, Vagi, & Scott, 2005). These may focus on biological, social, or cognitive
aspects. Among these risk factors are, e.g., delayed brain development, defects in innate
language acquisition mechanisms, deficiencies in auditory perception, difficulties to use
language’s rhythmic-prosodic properties to segment the heard auditory information,
deficient learning strategies, memory deficits, or an inadequate language environment.
Some of these risk factors will be discussed below. They belong to three main categories:
[1] General processing limitations, [2] specific deficiencies in auditory and language
processing, and [3] biological, genetical, and psychosocial risk factors.
General processing limitations
Children with SLI may be characterized by general processing limitations. Such limitations
may cause a wide spectrum of linguistic and non-linguistic deficiencies, including
limited working memory capacity (see, e.g., Maillart & Schelstraete, 2002), or insufficient
speed at information processing (see, e.g., Johnston & Weismer, 1983; C. A.
Miller, Kail, Leonard, & Tomblin, 2001; Weismer, 1985). Compared to age-matched
control children, SLI children were observed to be slower by a common factor on a
wide range of tasks (Kail, 1994). There is some discussion regarding the relation between
a reduced processing speed and the deficiencies of SLI children, specifically those
for grammar processing (Dannenbauer, 2004; Maillart & Schelstraete, 2002). However,
this risk factor is discussed controversially since the amount of deceleration in information
processing was not linearly related to the severity of language impairment (Lahey,
Edwards, & Munson, 2001).