Psycho 07

Discourse Comprehension

Discourse Comprehension

• Reasons for the increasing importance of discourse analysis: we rarely speak in isolated sentences. Sentences are more ambiguous or obscure apart from their discourse context. To understand sentences. Research resources for cognitive research.

Topics

• Discourse discussion Organization of discourse & comprehension strategies

• strategies & coherence

• memory presentation

• case study: narrative discourse

• Educational implication

Local & Global Structure

• Sentences have to be connected in conventional ways to be comprehensible. (Examples on p. 157)

• Local discourse structure or microstructure: the relationships between individual sentences in the discourse.

• Global discourse structure or macrostructure: the relationship between the knowledge of the discourse and the world knowledge.

• Both levels contribute to the coherence of a text.

Cohesion

• Semantic relationships between successive sentences

• Halliday (1976): the range of possibilities that exist for linking something with what has gone before

Category of Cohesion Category Examples Reference

Pronominal

Demonstrative

Comparative

Substitution

Ellipsis

Conjunction

Lexical

Reiteration

Synonymy

Hyponymy

The woman lost track of her little boy at the mall. She became very worried.

That was the worst exam I had all term.

It's the same band we heard last week.

My computer is too slow. I need to get a faster one.

I wish I had more talent. My sister has a lot more than I do.

Melissa flunked out of school, so she is looking for a job.

I saw a boy win the spelling bee. The boy was delighted afterward.

I saw a boy win the spelling bee. The lad was delighted afterward.

I saw a boy win the spelling bee. The child was delighted afterward.

Strategies to Establish Coherence

• Given/new strategy: three states

• 1. identify the given and new information in the current sentence

• 2. find an antecedent in memory for the given information

• 3. attach the new information to this spot in memory

Cases for Given/new Strategy: Direct matching

• The given information in the target sentence directly matches an antecedent in the context sentence.

• (9) We got some beer out of the trunk.

• (10) The beer was warm.

• We search for a concept rather than a word as the antecedent.

Cases for Given/new Strategy: Bridging

• Link the sentences without an antecedent.• (13) Last Christmas Eugene went to a lot of

parties.• (14) This Christmas he got very drunk again.• We make a bridging inference to mane sense of

the word again.• Bridging takes longer time in comprehension.

Cases for Given/new Strategy: Reinstating old information

• We have to reinstate the old information when the antecedent is far away (into the background).

• Examples: p. 162

• Reinstatements increase comprehension time.

Cases for Given/new Strategy: Identifying New Topics of Discourse

• With explicit markers for the new topic, such as “Now I want to move on to…”, it is easy to detect the new topic.

• In the case of implicit cues, we know little about the way comprehenders use.

Case Study (1) • Even in the true sciences, distinguishing fact from

fiction is not always easy. For this reason great care should be taken to distinguish between beliefs and truths. There is no danger as long as a clear difference is made between temporary and proved explanations. For example, hypotheses ( 假说 ) and theories are attempts to explain natural phenomena. From these positions the scientist continues to experiment and observe until they are proved or discredited （不足信的） . The exact status of any explanation should be clearly labeled to avoid confusion.

Case Study (2)• The health-care economy is replete （充满） with unus

ual and even unique economic relationships. One of the least understood involves the peculiar roles of producer or “provider” and purchaser or “consumer” in the typical doctor-patient relationship. In most sectors of the economy, it is the seller who attempts to attract a potential buyer with various inducements of price, quality, and utility, and it is the buyer who makes the decision. Where circumstances permit the buyer no choice because there is effectively only one seller and the product is relatively essential, government usually asserts monopoly and places the industry under price and other regulations. Neither of these conditions prevails in most of the health-care industry.

Role of Working Memory • Trade-off: We sometimes have to trade off the storage

in the worming memory for the processing and vise versa.

• Daneman’s test: reading span and reading comprehension

• Task: Read aloud series of sentences (processing) and recall the final word in each sentence (storage). Increased the number of sentences until the task could not be completed.

• Compared the reading span with the reading comprehension

• There was a significant correlation between reading span and reading comprehension.

Role of Working Memory• Findings: With medium and large distances, perfor

mance dropped off, especially for those with smaller reading spans.

• Conclusion: individuals with smaller reading spans had smaller working memory capacity, which made it difficult for them to comprehend references more than a few sentences back.

• Daneman also found the reading span correlated significantly with the verbal SAT scores. Both tests tap working memory process.

Whitney (1991): Test • Test: Read aloud difficult passages, and think out

loud during the reading.• Findings: • Both groups produced inferences. • High-memory span readers tended to so toward

the end of a passage• Low-memory span readers distributed the

inferences more evenly throughout the passage.• High-memory span readers’ inferences were more

general and more open-ended.• Low-memory span readers’ inferences were more

concrete.

Whitney (1991): Test

• Conclusion: The difficulty in retaining so much information in working memory led low-span readers to form concrete, specific inferences.

Educational Implications

• Active processing

1. relating new information to information in permanent memory

2. asking questions of the material

3. writing summaries or outlines of the material

Memory for Discourse

• Three levels:

surface representation

propositional representation

situational model

Surface Representations

• In this memory we remember the exact words that we encountered.

• Short lived.

• The surface representation or verbatim form of a sentence is stored in working memory only until its meaning is understood, then purged to make room for the next sentence.

Propositional Representations

• The meaning of the sentence.

• The number of propositions is related to reading time.

• Discourse is stored as a network of propositions.

Example of Propositional Network (discourse)

• Early French settlements in North America were strung so thinly along the major waterways that land ownership was not a problem. The Frenchmen were fur traders, and, by necessity, the fur traders were nomads. Towns were few, forts and trading posts were many, little wonder that the successful fur trader learned to live, act, and think like an Indian. Circulation among the Indians was vital to the economic survival of the traders.

Example of Propositional Network

Inferences and Propositional Representations

• Inferences are intrinsic to discourse structure. Authors leave out information that they think readers will be able to figure out.

• An inference is a proposition in the underlying discourse structure that is intended but not explicitly expressed by the author and thus must be drawn by the reader.

Inference

• Two conditions for automatic inference:

1. The inference must be necessary to make a text locally coherent.

2. The information on which the inference is based must be easily activated.

Implicit and Explicit Inference

• Explicit inference: A carelessly discarded burning cigarette started a fire.

• Implicit inference: A burning cigarette was carelessly discarded.

We store the implicit propositions right alongside the explicit propositions. (there is no difference between explicit and implicit propositions when the test is delayed by 15 minutes: Kintsch: 1974)

Implicit and Explicit Inference

Situational Models

• As we comprehend the propositions of a text, we construct a mental or situational model of the world as described by the text such as spatial layout, causal model.

Comparison of Three Levels

Schemata and Discourse Processing

• Activation of appropriate schemata: comprehension and memory are poor when we do not have a schema that corresponds to the story or we may have an appropriate schema in memory but fail to activate it for one reason or another.

• Reconstruction of schema-specific details: the activated schema serves as a retrieval plan, summoning up certain details rather than others by virtue of their centrality to the schema.

Educational Implications

• Connecting Propositions in Discourse:

Sentences are overlap in content and given information is used to introduced new information

We can benefit from a strategy of explicitly looking for relationships between concepts in discourse.

Educational Implication• Identifying the main points

Difficulty in determining main points may be traced to the presence of distracting and often confusing details.

Signals improve the immediate retention performance of readers whose comprehension was otherwise poor but did not affect the retention of good comprehenders.

Reder: retention was better when the material was presented in a condensed version rather than in a standard textbook version.

Giora: analogies in text did not facilitate comprehension and may actually impair recall.