Sign Reasoning PPT

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Sign Reasoning PPT Powered By Docstoc

  “Judging a book by
      its cover”
Sign Reasoning
 Assumes one thing or event is a reliable
  indicator of another thing or event
     the presence of one thing signifies the
      other, but does not cause the other.
     a flag at half mast
 signs can be:
     status symbols, economic indicators,
      political actions, physiological symptoms,
      or other indices.
 effect-to-cause reasoning is one form of sign
     example: an MD relies on symptoms
      (fever, sore throat) to make a preliminary
examples of sign reasoning
• “It has been 50,000 miles since your car was last
  serviced. You need a major tune-up.”
• “That guy‟s pants are „saggin‟ and he‟s wearing a
  Raiders jacket, so I‟ll bet he‟s a gang member.”
• “The last two times I ate at Coco‟s, the same
  waitress took my order. I think she digs me.”
• “Naomi didn‟t pick up when I called her, so I guess
  she‟s not home.”
illustration of sign

                                           Grounds: leaves are
Claim: Winter is                              falling, birds are
   approaching                                flying south,
                                              squirrels are
                                              gathering nuts
                   Warrant: These
                     characteristics are
                     associated with the
                     advent of Winter
real-life examples of sign
• Signs your significant other is fooling around
• Warning signs of suicide.
• Signs that Iran is seeking nuclear weapons rather
  than commercial nuclear technology.
• Does the location of U.S. aircraft carriers signal the
  likelihood of military action?
• Do economic signs suggest the economy has hit
• inferring things about a person‟s values or lifestyle
  from the person‟s appearance.
Al Gore uses sign reasoning to
prove global warming is occurring
 • Gore cites
   evidence, such as the
   fact that the warmest
   years on record have
   all occurred since
   1990, as evidence of
   global warming
 • Melting glaciers and
   more severe hurricanes
   are signs of warming
a sign that it is time to
replace your tires
  • place a US penny into a
    groove between tread, with
    Lincoln's head down. If the
    tread is at or beyond the top
    of Lincoln's head you have at
    least 3/32-inch of tread left, a
    satisfactory level.
  • if you can see above
    Lincoln's head or any of the
    "In God We Trust" letters
    above his head, then you are
    ready for a new tire.
Poker tells: can you tell a player’s
hand from nonverbal cues?
• Glancing at chips: “if a player
  immediately glances down at his chips
  as soon as he sees his cards, it almost
  always means that a player's hole cards
  are strong (from
• Sitting up straight, leaning forward:
  A player who has been slouching
  suddenly seems to take interest in the
  game and leans forward is usually
  holding a strong hand (from
• Splashy bet: If a player makes a large
  bet by throwing his chips into the pot in
  a grand, exaggerated fashion, he is
  trying to bluff you out of the pot (from
You are what you own: Material
goods as status symbols
• Consumption and materialism often
  function as status symbols in
   • Rolex watches, Tiffany jewelry
   • Hummers and other luxury cars
     as urban status symbols
   • “trophy” wives
   • designer clothing (Armani,
     Gucci, etc.)
   • state of the art technology
     (plasma TVs, wireless laptops,
     GPS devices, cell-phones,
   • platinum credit cards
   • membership in country clubs
signs of steroid use and
eating disorders
• If an athlete bulks up
  suddenly, is it a sign he
  is on steroids?
• If an actress loses
  weight is it a sign she
  has an eating disorder?
                                                Barry Bonds

                               Jason Giambi

                          Angelina Jolie

                                Lindsay Lohan
 Is the purple Teletubby gay?

• The Rev. Jerry Falwell charged
  that Tinky Winky was gay because
  “He is purple -- the gay-pride
  color; and his antenna is shaped
  like a triangle -- the gay-pride
handwriting analysis as sign
• Handwriting experts analyzed the
  letters containing anthrax for clues
  about their sender
 “Circumstantial evidence” is
 based on sign reasoning
• Circumstantial evidence: inferring • Sherlock Holmes in
  one fact from another.               the Boscombe Valley
   • Direct evidence: a witness        Mystery:
      testifies that he saw a          "Circumstantial
      defendant shoot a person, and    evidence is a very
      the person subsequently died     tricky thing. It may
      of a gunshot wound. The          seem to point very
      witness would be providing       straight to one thing,
      direct evidence of a material    but if you shift your
      fact in the case.                own point of view a
   • Indirect evidence                 little, you may find it
      (circumstantial): a witness      pointing in an equally
      testifies that he heard a shot   uncompromising
      and when he arrived on the       manner to something
      scene he saw the defendant       entirely different."
      standing over the body with a
      smoking gun in his hand.
damning circumstantial
• Laci Peterson's body
  washed up a few miles away
  from where Scott Peterson
  said he was fishing alone
  months earlier.
• He returned to the location
  three more times before her
  body was discovered.
• Could it be just a
increased “chatter”: as a sign of
terrorist activity?
• May 20, 2003: Homeland Security
  Secretary Tom Ridge said there is
  no "credible, specific information"
  about targets or method of attack,
  but he says increased “chatter”
  suggests attacks on U.S. soil may
  be forthcoming.
applications of sign reasoning

• in business: economic indicators, inflation rate,
  consumer confidence, housing starts, unemployment
• in advertising: associating products with status,
  prestige, elitism
• in medicine: symptoms, fever, dizziness, blood
• in religion: 666, biblical signs of the apocalypse
• in law: circumstantial evidence
• in tabloids: if two celebrities are seen together, it is
  taken as a sign they are having an affair, or if they
  are not seen together it is taken as a sign of a
fallible versus infallible signs

• fallible: nonverbal correlates of deception.
• fallible: Where there is smoke, there is fire.
• infallible: genetic markers as proof of identity.
• infallible: a shadow signifies the presence of a physical body
    • Note: infallible signs are much more common in the
      natural sciences
tests of sign reasoning

• Does one fact or event allow one to reasonably infer
  another fact or event?
• How reliable or consistent is the sign?
• Is the sign fallible or infallible?
• Is the sign ambiguous (could it signify something else?)
• Is the sign relevant (could it signify nothing?)
• Are there a sufficient number of signs?
• Are there negative or contradictory signs?