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

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

3. 3 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.

4. 4 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?

5. 5 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

6. 6 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 (McArthur et al. 2000) Explanation: central phonological processing deficit

7. 7 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?

8. 8 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!

9. 9 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 (vL, van Kruistum & Parigger) Here is a link between tense and executive function

10. 10 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

11. 11 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

12. 12 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

13. 13 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

14. 14 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...

15. 15 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

16. 16 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

17. 17 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/NoGo tasks relate to verb tense