Coherence structure and lexical cohesion in expository and persuasive texts
On the Interaction of Relational Coherence and Lexical Cohesion in Expository and Persuasive Text...
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Transcript of On the Interaction of Relational Coherence and Lexical Cohesion in Expository and Persuasive Text...
10th International Pragmatics Conference Gothenburg, 8-13 July 2007
On the Interaction of
Relational Coherence and Lexical Cohesion
in Expository and Persuasive Text Genres
Gisela Redeker & Markus EggUniversity of Groningen
Outline
• Coherence and cohesion
• Coherence relations and discourse structure
• Cohesion (esp. lexical cohesion)
• Interaction between coherence and cohesion
• Pilot study on local coherence and cohesion
• Future work
Coherence and Cohesion
Coherence: how a discourse is making sense
relations between discourse segments (clauses, sentences,
etc.); recursive application yields a hierarchical discourse
configuration
Cohesion: how discourse elements stick together connectives; referential or lexical relations
Coherence
• Three components of coherence (Redeker 2000)– Content relations (additive, causal, temporal, contrastive, etc.)
– Pragmatic or intentional relations (evidence, justification,
concession, etc.)
– Sequential or textual relations (summary, restatement,
segment boundary, etc.)
• Rhetorical Structure Theory (RST; Mann & Thompson
1988, Taboada & Mann 2006)– Subject-matter relations (= content)
– Presentational relations (= intentional and textual)
Coherence Relations and Discourse Structure
Example (from Asher & Lascarides 2003):
(1) Max experienced a lovely evening last night. (2) He had a fantastic meal. (3) He ate salmon. (4) He devoured lots of cheese. (5) He won a dancing competition.
Discourse Structure (RST-analysis):
Cohesion
Grammatical cohesionConjunction (marks transitions between messages)
Reference, ellipsis and substitution
Lexical cohesionParadigmatic:
• Repetition
• Synonymy, antonymy, hyponymy, meronymy
Syntagmatic:• Collocation
Cohesion
Grammatical cohesionConjunction (marks transitions between messages)
Reference, ellipsis and substitution
Lexical cohesionParadigmatic:
• Repetition
• Synonymy, antonymy, hyponymy, meronymy
Syntagmatic:• Collocation
Discourse structure and cohesion aligned
referential chain
Discourse structure and cohesion aligned
hyponymy
Discourse structure and cohesion aligned
meronymy
Discourse structure and cohesion aligned
collocation
Discourse structure and cohesion aligned
referential chain
hyponymymeronymy
collocation
Discourse Structure and Lexical Cohesion: Alignment and Divergence
1-4
1-2
(1) Schools tried to teach students history of science.
Conjunction(2) At the same time they tried to teach them how to think logically and inductively.
Conjunction
3-4
Volitional-result
(3) Some success has been reached on the first of these aims.
Contrast(4) However, none at all has been reached on the second.
Contrast
This example figures prominently in the ongoing discussion on discourse configuration (Danlos 2004, Wolf & Gibson 2005, Egg & Redeker 2006)
Discourse Structure and Lexical Cohesion: Alignment and Divergence
1-4
1-2
(1) Schools tried to teach students history of science.
Conjunction(2) At the same time they tried to teach them how to think logically and inductively.
Conjunction
3-4
Volitional-result
(3) Some success has been reached on the first of these aims.
Contrast(4) However, none at all has been reached on the second.
Contrast
Cohesion and Discourse Processing
• Lexical chains are used for discourse segmen-tation (e.g. Morris & Hirst 1991; Stokes 2005).
• Centrality of concepts in cohesive networks reflects importance (Hoey 2005, Tanskanen 2006).
• Readers’ paragraphing judgements are highly correlated with breaks in cohesion (e.g. Hoey 2005).
Genre-specific coherence 1
• Encyclopedic text
Genre-specific coherence 2
• Fund-raising letter (Abelen et al. 1993)
Hypothesis
Our discourse-analytic experience suggests that the interaction of discourse structure and cohesion is genre sensitive. In particular:
Expository and descriptive (i.e., thematically organized) texts will show higher lexical cohesiveness and closer alignment between discourse structure and cohesive structure than persuasive (more intentionally structured) texts.
Pilot study
Informative texts Persuasive texts
Facts & events
Wall Street Journal 358 words
24 RST-relations
Fundraising letters514 words
42 RST-relations
CarsMagazine articles
766 words58 RST-relations
Advertisements760 words
66 RST-relations
Total 1124 words82 RST-relations
1274 words108 RST-relations
Test of genre differences
Presentational Relations (%)Informative Persuasive
Facts & events 8.3 % 42.4 %
Cars 6.9 % 57.1 %
Total 7.3 % 48.1 %
Texts labelled informative should have fewer presentational (reader-oriented) RST-relations than texts labelled persuasive.
Local lexical cohesion (average # links per adjacent segment pair)
Facts & Events Genres
0
0.5
1
1.5
2
2.5
WSJ Articles Fundraising Letters
related
unrelated
Local lexical cohesion (average # links per adjacent segment pair)
Informative and persuasive texts on cars
0
0.5
1
1.5
2
2.5
Car Mag. Articles Car Advertisements
related
unrelated
Preliminary conclusions
Alignment hypothesis supported– Even these simple local counts show that cohesion appears
to align with local coherence in informative texts (WSJ, car magazine articles).
But:– Indications for a lack of alignment in persuasive texts were
only found for the fundraising letters, but not for the car ads.
Future WorkRefining the descriptive work
– Include non-local cohesive links. – Differentiate types of cohesive links.
Comparing the two ways of organizing texts– Compute distances between text segments on the basis of
cohesive linkage and compare them to distances derived from discourse structure.
– Compute and compare the centrality of text segments in cohesive networks and in discourse structure.
Testing the cognitive effects – Relate to readers’ judgements of paragraphing and centrality.– Test effects of alignment in processing.