First Language Acquisition Developmental Language Disorders and Executive

First Language Acquisition, Developmental Language Disorders and Executive Function Anne Baker (ACLC) Michiel van Lambalgen (ILLC) 1

Content of the talk • The language behaviour of children with Specific Language Impairment (SLI) • Theoretical explanations • Executive functions 2

What is Specific Language Impairment (SLI)? • SLI refers to pervasive impairment in the development of language (in the absence of other problems) • Deficits may be apparent in all domains of language, but some domains appear to be more affected than others. 3

Affected Domains Grammar: Verb morphology is particularly affected, but this varies between languages. (project on inflection and SLI) Explanations: • SLI is a representational deficit – Agreement Deficit hypothesis (Clahsen) • SLI is a processing deficit – Sparse morphology hypothesis (Leonard) Evidence that this is the most promising explanation but possibly not for all children? 4

Affected Domains Phonology: some have clear phonological problems in their speech, but most seem to do badly on non-word repetition task (project on non-word repetition in SLI) Explanation: central phonological processing deficit BUT recent results (Rispens & Parigger) indicate the non-word repetition is associated with reading problems not per se with SLI 5

Affected Domains Reading: In addition to spoken language problems, children with SLI often also show reading problems • Approximately 50% of children with SLI are also diagnosed with developmental dyslexia (Mc. Arthur et al. 2000) Explanation: central phonological processing deficit 6

Alternative explanations • Is there a link with non-linguistic Executive Function? • Could there be a totally different explanation of SLI that will cover all or some of these children? 7

Back to tense • Deficits in tense marking prominent in SLI - is this morphosyntactic problem only? (Clahsen) • This depends on the grammar formalism adopted • E. g. in unification-based grammars tense violations are semantic: • ‘Yesterday, Vincent paints his boat’ • Morphosyntactically fine! 8

Tense and discourse • Tense also has important discourse functions - facilitating computation of event structure • Deficits in tense production may point as well to difficulties with corresponding discourse operations • For which there is evidence in ADHD (v. L, van Kruistum & Parigger) • Here is a link between tense and executive function 9

What is executive function? • An umbrella term for processes responsible for higher-level action monitoring and control • that are necessary for maintaining a goal • and achieving it in possibly adverse circumstances 10

Executive function is composed of • Planning (i. e. devising a linear order of actions) • Initiation (of action sequences) • Inhibition (. . . ) • Monitoring (. . . ) • Co-ordination (. . . ) • Control (. . . ) • Goal maintenance in working memory 11

Computational aspects of EF • Given the goal, compute the plan leading toward the goal using regression • Uses world-knowledge (search) and unification, to apply general rule to particular situation • Re-computation of the plan if new circumstances (monitoring) make the original plan no longer feasible • This requires inhibition 12

What has logic got to do with it? • Logic provides a high-level formal description of executive function, as • ‘Closed world reasoning for rules allowing exceptions’ • This gives theoretical coherence to the concept of EF • And constructs a bridge from EF to language 13

Why is EF relevant to language (disorders)? • Connections between planning and language • Syntax (Greenfield, Steedman, . . . ): same recursive structure as in planning? • Discourse coherence (Slobin, Trabasso, . . ): are events described by sentences linked together like actions in a plan? • Also semantics. . . 14

Why is EF relevant to language (disorders)? • Semantics: suppose the meaning of a sentence is given by a discourse model (Kamp, . . . ) • Claim: the computation of the discourse model is the brief of EF • The discourse is a set of goals • The discourse model is a plan to achieve the goals 15

Discourse models as plans: tense • Verb tenses are formally represented as goals in the same sense as goals are used in planning • The goal is to introduce the event corresponding to the tensed VP into the event structure • Goal has to components: – to locate of event in time – to mesh it with events already present 16

Putting 2 and 2 together • Semantic computations (or at least some) are analogous to computing a plan • EF is responsible for motor planning • Hypothesis: EF is also responsible for planning-like computations for language • Therefore, disorders in EF should correspond to language disorders (and conversely) • Applications to ADHD – Go/No. Go tasks relate to verb tense 17