Computational Models of Discourse Analysis

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Computational Models of Discourse Analysis

• Carolyn Penstein Rosé
• Language Technologies Institute/
• Human-Computer Interaction Institute

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Computational Approaches

• Two steps
• Step 1 Metaphor recognition
• Step 2 Metaphor interpretation
• Does this paradigm cover everything that Lakoff
  and Johnson place under the heading of metaphor?

Examples from the paper

• Lakoffs concept
• Metaphors structure how we think about an event
  or state.
• The way we think affects
• what we expect to happen,
• what we do,
• how we respond to what occurs during an event,
• and how we talk about what we and others are doing

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Announcements!

• Questions about presentations for next time?
• Rearranged syllabus slightly see Drupal
• Posted responses to posts
• Readings for next unit most of rest of semester
  posted
• Next unit focuses on Sentiment Analysis
• Product review dataset will be ready by next
  Monday for Assignment 3
• Note we wont meet during Spring Break
• Unit 3 has a break too!
• We wont meet on Wed, March 30 since several of
  us will be away

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MIP Metaphor Identification Procedure
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(No Transcript)
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Growing Interest?
References
Automatic Approaches
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Recent Approaches to Detection

• Peters and Peters 2000 Mined wordnet for
  abstract concepts that share word forms such as
  publication-publisher
• Mason 2004 Mine an internet corpus for domain
  specific selectional restriction differences
• Birke and Sarkar 2006 Start with seed sentences
  that have been annotated with figurative versus
  literal, and then do something like an instance
  based learning approach
• Gedigan et al. 2006 extract frames for MOTION
  and CURE from FrameNet, then extract sentences
  related to these from PropBank. Annotate by hand
  for metaphoricity. Use a maximum entropy
  classifier.
• Krishnakumaran and Zhu 2007 Look for sentences
  with be verb. Check for hyponymy using
  WordNet. If not there, look at bigram counts of
  subj-obj. If not high, then might be
  metaphorical.

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What would Fass say?

• Problem with selectional restrictions as
  evidence
• Will detect all kinds of nonliteral and anomalous
  language regardless if it is metaphorical or not
• Common metaphorical sense (i.e., dead
  metaphors) will fail here
• Some statements can be interpreted either way
  All men are animals

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Recent Approaches to Interpretation

• Metaphor based reasoning framework reason in a
  source domain and apply reasoning to the target
  domain using a conceptual mapping
• Narayans KARMA 2004 parsed text as input
• Barnden and Lees ATT-Meta 2007 logical forms
  as input
• Talking Points 2008 uses WordNet, then uses
  minimal edits to bridge concepts
• Makeup is the Western burqa
• Shutova 2010 uses a statistical paraphrase
  approach

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Shutovas Take Away Message

• Approaches from the 80s and 90s were rule based
• Knowledge engineering bottleneck
• Shutovas work give some evidence that metaphor
  can be handled using a more contemporary (i.e.,
  machine learning) paradigms
• Cast the metaphor interpretation problem as a
  paraphrase problem so you can use statistical
  machine translation approaches

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Does paraphrase cut it?
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Do you see a metaphor here?
How much of the problem can be solved by
paraphrase?
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Do you see metaphor here?

• Evey Who are you?V Who? Who is but the form
  following the function of what and what I am is a
  man in a mask.Evey Well, I can see that.V Of
  course you can, Im not questioning your powers
  of observation, Im merely remarking upon the
  paradox of asking a masked man who he is.Evey
  Oh.V But on this most auspicious of nights,
  permit me then, in lieu of the more commonplace
  soubriquet, to suggest the character of this
  dramatis persona.
• pauses for a few seconds
• Voila! In view humble vaudevillian veteran, cast
  vicariously as both victim and villain by the
  vicissitudes of fate. This visage, no mere veneer
  of vanity, is a vestige of the vox populi now
  vacant, vanished

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Datas Identity

• We see evidence of how Data is framing his
  identity.
• Do we see metaphor here?

• Lakoffs concept
• Metaphors structure how we think about an event
  or state.
• The way we think affects
• what we expect to happen,
• what we do,
• how we respond to what occurs during an event,
• and how we talk about what we and others are doing

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Another spin on Metaphor Recognition

• Perspective modeling work
• Liberal versus Conservative
• Pro or Against
• Sentiment analysis more generally
• Different computational approach
• Skips step 1 assumes all language represents
  perspective
• Simplifies step 2 goal is to recognize a
  category rather than rephrase
• Usually models are based on word distributions
• Word vectors with weights
• Topic models
• Well explore this in the next unit

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Framing an Event in Progress

• Where does the paradigm for understanding
  metaphors break down with examples like this?
• Step 1 recognize metaphor
• Step 2 map to literal meaning
• Still understanding a concept/situation by
  comparison with another one

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Breaking the Paradigm

• What can we do with conversational data?
• How do we recognize that a metaphor is in play?
• What would it mean to do the interpretation?

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Questions?