Language and CognitionColombo, June 2011

Day 9Aphasia: disorders of syntax

Agrammatism

• Deficits in syntactic aspects of production and comprehension of sentences

• Word level is often (comparatively) spared• Agrammatism has been identified in other

clinical populations, but has been studied most extensively in Broca’s aphasics

Characteristics of Broca’s aphasia

• Spoken language:– Short phrase length, limited range of syntactic structures– Telegraphic speech – primarily content words (function word

omission)– Speech may be very effortful – prosody is often abnormal– Articulatory difficulties are common (apraxia / dysarthria)– Poor repetition– Disrupted naming ability– A range of impairments in reading and writing

• Receptive language: – Relatively good for single words and short sentences– Impairments in comprehension of grammatically complex

sentences• Often very good insight into deficits

Syntax

• Structure in language – just like structure in (the rest of) nature

The sailor is kissing the girl

Syntactic movement

• The sailor is kissing the girl• Who is the sailor kissing?

• The sailor is kissing who• Who is the sailor tis kissing tthe girl/who?

• Movement leaves “traces” behind

Mapping

• It’s not enough to “know” (implicitly) what the structure of a sentence is

• We also have to know how to interpret the structure

• Thematic roles (also called theta theory, argument structure etc): – subject of a sentence is usually the AGENT of the

verb– Object of a sentence is usually the PATIENT or

THEME of the verb

Mapping

• Theta-roles: assignment of interpretive roles to syntactic objects

subject verb object Grammatical rolesJohn kissed Mary

Theta roles

• Non-canonical word order reliance on grammatical structure

object verb subject

John was kissed by Mary

Agent Patient

Agent?? Patient??

In English….

• Mapping between theta roles and grammatical roles is achieved by using word order

• Subject first = Agent• Object first is non-canonical, and indicates a

passive

In Sinhala….

• Literary and colloquial language varieties• There is a passive construction in the literary variety of

Sinhala

• Mapping between theta roles and syntactic roles is achieved using grammatical morphemes – NOT by changing word order

In Sinhala….

• The colloquial variety only has the active construction

• BUT there are volitive and involitive ways to express the same sentence

In Sinhala….

• Sinhala passive requires the Agent to be in a position at the front of the sentence

• Other constructions seem to show free word order

All Sinhala examples are from Gunasinghe & Kess, 1985http://sealang.net/sala/archives/pdf8/kess1985preliminaries.pdf

Agrammatism in English and Sinhala

• English: omitted morphemes• Sinhala: substituted morphemes

• English: passive is interpreted like active• Sinhala: nonvolitional may be interpreted like

volitional

Agrammatic comprehension

• Sentence-picture matching tasks• Non-reversible sentences are easier to

interpret than reversible ones• Canonical sentences – subject-verb-object

– are easier to interpret than non-canonical ones– Passive vs active– Object relative vs subject relative

• Less complex phrase structure makes a sentence easier to understand

The mother is calling her child who has light hair

The woman who is fat is kissing her husband

Syntactic trees

Questions (in English)

In Sinhala…• Sinhala is considered a “wh in situ” language• That means it does not move wh elements from one position in

the sentence to another• BUT whether we are speakers of English or Sinhala (or whatever)

there is evidence to show that we all apply the SAME processes of linguistic analysis to understanding sentences

• Underneath it all, it seems that every language DOES move WH items

• In some languages, the WH item is pronounced in its moved position (this is called OVERT movement)

• In some languages, the WH item is pronounced at the trace position (this is called COVERT movement)

Maybe agrammatism = central syntactic deficit

• Caramazza and Zurif, 1976• Agrammatic aphasics DO have comprehension

problems• They have difficulties understanding sentences

when they must rely on syntactic knowledge to do so

• This parallels their production deficits• They have lost knowledge of syntactic structure

(affects all modalities in similar ways)

Another view: is agrammatism a problem with mapping?

• Problems with the central syntactic deficit account:– agrammatics do have some ability to interpret complex

utterances - in particular, they are quite good at grammaticality judgement

– Some agrammatics are modality-specifically impaired – note assumptions of central deficit hypothesis

– Some fluent aphasics show comprehension deficits similar to those found in Broca’s aphasics

• Perhaps the deficit is not central to syntax, but involves only the mapping between syntax and interpretation of sentences (Saffran et al 1980)

Is agrammatism a problem with syntactic representations? The trace deletion hypothesis

• We have seen that things move around in sentences• And we have seen that interpreting sentences does not

just mean knowing where the subject and the object are – it means knowing what theta roles to assign, too

• In the normal language system, movement leaves traces behind

• Theta roles can be assigned to traces, and then transmitted to the moved item

• Grodzinsky (1990) asked: what if traces get deleted from the syntactic representation?

• Maybe this is what happens in agrammatism• The trace deletion hypothesis

If traces are deleted…

• No problem understanding a sentence where nothing has moved (i.e., canonical word order)

• Problems come when trying to understand sentences where movement has occurred (i.e., non-canonical word order)

• Without traces to help them understand where the moved elements have come from, agrammatic aphasics cannot figure out the roles of the subject and the object in a sentence

• So they guess chance performance

In Sinhala…

• If traces are deleted, word order will be free• This might change things for production:• WH items might be produced in moved

positions? – may not matter given free word order

• But it is predicted to cause problems for comprehension, because the reconstruction of underlying structure is important for sentence interpretation in every language

Trace Deletion Hypothesis• Assigning a theta role to ‘the girl’

should be no problem – no trace involved in that

• P ‘by’ assigns a theta role of Agent – so ‘the girl = Agent

• But, if traces are deleted, then ‘the boy’ has no theta role

• So follow your instincts – USUALLY, the first noun in a sentence is the Agent

• So ‘the boy’ is probably an Agent• Now, the agrammatic thinks:

‘the boy’ = Agent AND‘the girl’ = Agent

• What to do? GUESS at the right interpretation of this sentence

A simpler view… • Ouhalla (1993) and

others• The syntactic tree of

a typical sentence is large and complex

• People who have an agrammatic deficit may be unable to access higher parts of the tree

Recommendations:

• So, we should not be using the higher parts of the tree, so far as possible, when working with agrammatic patients

• Can educate communicative partners this way too – show how a wh question involves a great deal of syntactic complexity; a yes-no question is relatively simpler; passives, relative clauses and locatives may overload the system very easily

• simplest of all is an active, nonreversible statement

Planning intervention

What person can do

cannot do

does do

What person needs to do

wants to doclosing the gap

Planning interventionWhat person cannot do

can do

does do

What person needs to do

wants to doclosing the gap

Cannot produce a variety of syntactic constructions

Communicates through use of substantive words and occasional, simple syntactic constructions

Has relatively spared auditory comprehension

Desired ability

Person needs/wants to make statements & requests

needs/wants to ask questions and socially converse

Treating sentence level deficits: a mapping approach

• Recall: the Mapping Hypothesis– There is not a problem in syntax per se; the problem is in

assigning thematic roles to grammatical objects• MAPPING THERAPY • Present a typed sentence• Make the thematic roles explicit

1. Where are thematic roles assigned from? • What’s the main word in this sentence? What is this sentence

about? What action is happening here?2. What’s the Agent?

• Which one is doing the V-ing?3. What’s the Patient?

• Which one is getting V-ed? What is s/he V-ing?

• Pre and post testing• Generalization issues

Schwartz, MF, Saffran, EM, Fink, RB, Myers, JL, Martin, N. (1994) Mapping therapy: A treatment program for agrammatism. Aphasiology, 8: 19-54.

Treating sentence level deficits: TDH

• Linguistic specific treatment (LST) Thompson et al, 1993 onwards

• Train subjects to recognize parts of the sentence, and then show them how to move things to form questions

• Generalized to new sentences, and also from ‘who’ questions to ‘what’ questions

• Also helpful for training on cleft sentences; may extend to passives

Thompson, C. K., Shapiro, L. P., Ballard, K. J., Jacobs, B. J., Schneider, S. L., & Tait, M. E. (1997).Training and generalized production of wh- and NP-movement structures in agrammatic aphasia.Journal of Speech, Language, and Hearing Research, 40, 228–244.

The man sending flowersis

whatAgent Aux verb

The man sendingis what

Agent verb

1. Move Aux to front (= I to C movement)

The man sendingiswhat

Agent verb

2. Move wh word to front (= wh movement to spec, CP)

Production of grammatical morphemes

• Production deficit in nonfluent aphasics• Cannito & Vogel, 1980: Training regular plurals

on nouns – no carryover to irregular plurals• Thompson et al 1982: Matrix training of

prepositional forms, allows for testing of generalization

• Kearns & Salmon 1984: Training on copula is found to generalize to auxiliary is (but not to is+locative)

NP1The river

NP2The tree

NP3The bridge

PP1Under the hill

The river is under the hill

PP2Behind the house

The tree is behind the house

PP3Beside the mountain

The bridge is beside the mountain

Training sentence production

• Syntax Production Program for Aphasia (Helm-Estabrooks 1981) / Direct Production Training (Wambaugh & Thompson 1989)

• Story completion format• Again, limited generalization to untrained

sentence types• Little effect on spontaneous language

production

Functional communication• E.g. Promoting Aphasics Communicative

Effectiveness (PACE)– Clinician and client participate equally– There is an exchange of new information– Speaker can choose modality– Feedback focuses on adequacy of message

• Training conversational partners• Spouses, volunteers

– Get the message in– Provide a means for getting messages out– Maintain the flow of conversation– You have to want to communicate

The importance of assessment• Assessment can be hypothesis driven• We need to compare the observed deficits with a model

of normal processing• Then we can formulate a hypothesis about what has

gone wrong for some individual – and what they can still do

• Example: if someone has a problem with wh question production– Could be an issue with syntactic movement– So test other constructions involving movement – such as

passives, object relatives– If they are bad at these also, then movement may indeed be the

problem– If they are good at these, in contrast with questions, then maybe

their problem is one with representing higher levels in the syntactic tree

– Then you test other constructions involving higher levels in the tree – such as embedded clauses

The importance of assessment

• If we have a model, we can test / assess at each level of the model and form more precise hypotheses about the nature of the Pt’s impairment more focused intervention

• Relating aphasic language impairments to models of normal language function at least “forces one to think hard and with precision about the patient” (Byng et al 1990)