The cognitive psychology of language – 2

1. The cognitive psychology of language – 2 • Now that we know how words are recognized • How are they produced in the first place? • Word production is the process of turning thoughts into sounds • Concepts  phonemes • This process is a little complex • Take into account both semantics and syntax

2. Choosing the right word • Syntax plays a large role • Adverb, noun, verb? - depends on how far along your sentence you are • Tense and number : “All your base are belong…” • Semantic context also plays a role • If you have used a word before, replace with a pronoun • Semantic priming will ‘force’ certain words • Increase the probability of a group of words being chosen

3. Lexicalisation • Once you have chosen the concept, convert it to sounds • Lexicalisation • A two stage process • Stage 1: Concept activates a lemma which has a semantic representation and syntactic information (‘lemma selection’) • Stage 2: The lemma activates the lexeme, aphonological form of the word (‘lexeme selection’)

4. Tip-of-the-tongue • Evidence for the 2-stage model comes from the tip-of-the-tongue state • Unable to retrieve a word even though you know you know it! • Can occur with extremely common words • Different from forgetting a word • Completely forgetting would be a failure at lemma selection • Failure at lexeme selection leads to tip-of-the-tongue state (know the word but cannot find the sounds to say it)

5. Sentence comprehension • Understanding sentences is quite complex • A lot of meaning must be extracted from the syntax The teddy bears beat up the emu. • Who did what to whom? • Did it happen now, or before? • Did it hurt the emu? • Was it a fair fight? • Need syntactic, semantic and contextual knowledge

6. Researching sentence processing • Extremely difficult • Process if very fast, automatic and pre-conscious • Look for how hints in how it fails • Same as perception research: try to fool the system and see how it reacts • Make use of ambiguities in language rather than illusions

7. Ambiguities in language • Two forms of ambiguity • Structural ambiguity (ambiguity in syntax) • Lexical ambiguity (ambiguity in semantics) • Structural ambiguity The emus bought the teddy bear traps. • Lexical ambiguity The priest married my sister.

8. What ambiguities say about processing • Sentences are processed according to the “immediacy principle” • Figure what each word does as we go along The horse raced past the barn fell • Make assumptions about sentence meaning as we go • eg. assume the first verb we hear is the main verb • Generally works because expectations are based on experience with real sentences

9. Evidence for processing immediacy • Surprise expressed by people at garden-path sentences The emu sold the honey farm for a lot of money wanted to kill the teddy bear. • Eye fixation studies • A lot longer is spent processing the second verb • The confusion causes people to stop reading and reconcile the second verb with the previously read part

10. Processing syntax • Sentence parsing can be thought of as recursively applying a set of rules to a sentences • Phrase structure rules • These rules have been defined by linguists • Expresses the hierarchy well • Drawn as phrase trees • Conveys the relationship between surface and deep structure • Separates semantic and syntactic structure well

11. sentence verb phrase noun phrase noun verb article noun phrase article noun emu loaded the shotgun. The Phrase tree example

12. Do we build trees when parsing? • It doesn’t look like it • Sentences which are syntactically different are very similar in meaning The teddy bears built the pipe-bomb The pipe-bomb was built by the teddy bears • Fodor: we use a series of heuristics (rules of thumb) • Noun-verb-noun is usually active voice, subj-v-obj • A ‘minimal effort’ approach (add new words into the structure which requires least effort to process

13. Sentence production • Putting complex ideas into words • Include notions of time, politics, semantics • Studied by looking at slips of the tongue • When you say something other than what you meant! • Actually quite systematic • Involve swapping one word, or phoneme for another • Categorised by Garrett (1975)

14. Slips of the tongue (Garrett, 1975) • Anticipation error • Shoot the emu!  Emu the emu! • Word exchange • Buying a nuclear scientist a drink  Buying a drink a nuclear scientist • Perseveration • We will steal the uranium shipment  We will steal the sturanium shipment • Word substitutions • The CIA planted a listening device  The CIA planted a talking device • Morpheme exchange • The emus reinforced their houses  The emus housed their reinforcements

15. Garrett’s model of sentence production (1975) • A state-based information processing model • ‘assembly line’ model • Four states which transform the intended message into speech • Derived from study of slips • Each slip must come from a different sub-process • At each transition, the message can become garbled • Slip of the tongue; one type per transition

16. Garrett’s model State 1: Message Level State 2: Functional Level Word substitution slips State 3: Positional Level Sound exchange slips State 4: Phonetic Level State 5: Articulation Level

17. 1: Message Level • The idea is conceptualized • Completely abstract (mentalese?) 2: Functional Level • Match semantic & thematic concepts to abstract ideas • Actors, objects, etc. • Word substitution (content) slips can occur • Because you may pick the wrong semantic carrier for the idea

18. 3: Positional Level • Syntactic structure is used to order and modify the words • Sound exchange slips can occur • Because syntactic modification needs sounds to be added to words 4:Phonetic Level • Convert words into phonetic representations • Tip-of-the tongue problems can occur • Fail to match lemmas with lexemes

19. Is speech production linear? • Some debate • Do the levels interact with each other? • The teddy bears’ defense is strormidable – a mixed error (phonological & semantic) • Dell (1986) – suggests an interactive network to account for this • A connectionist model

20. Dell’s idea • A parallel distributed interactive model • The message begins as activation to concept nodes (high level) • Activation spreads downwards to activate other nodes • These include nodes that encode syntactic structure • The most activated nodes at the end is the sentence that is produced • Can lead to errors

21. Connectionism and recursion • Connectionist models have not done well in explaining recursion • Computer models of maths formulas are quite awkward • Simple rule based systems fare better • Connectionist systems dno’t deal well with substitution grammar • The <clause> was shot by the <clause>