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Reciprocal Altruism _cont_

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					Reciprocal Altruism II

       Psych 250
        10/2/07
            Announcements
• First Research Opportunity (2 credits)
  – Posted across from Gartley 210B
  – Don’t show up during last ½ hour
• Second Research Opportunity (1 credit)
  – Also posted across from Gartley 210B
• Alternate Assignments posted on the web
           1   2   3                 4          TOTAL

 TFT

Strategy   D   D   C                 D
   X



                                            Strategy X
                                         Cooperate      Defect


                         Cooperate
                                          TFT: 5          TFT: 1
                                           X: 5            X: 8
                   TFT
                         Defect




                                           TFT: 8         TFT: 3
                                            X: 1           X: 3
                From last time
•   Modus Ponens
•   Modus Tollens
•   Wason selection task
•   Do we use the rules of formal logic to reason?
•   The descriptive problem
•   The drinking problem
•   What was the difference?
               WASON SELECTION TASK
Told that the following cards have a letter on the top half and a number on the bottom half.
Which, if any, of the pieces of paper do you need to remove to see if the following rule has
    been violated?

  If the card has a 7 on top, then there is an E on the bottom.


Ponens: Given P  Q                                                Tollens: Given ~Q  ~P



               7                    3                    6                      7

            X                      E                     E                      S

           P                    ~P                      Q                     ~Q
               WASON SELECTION TASK
Told that the following cards have a letter on the top half and a number on the bottom half.
Which, if any, of the pieces of paper do you need to remove to see if the following rule has
    been violated?

   If you are drinking beer, then you must be 21 or older.


Ponens: Given P  Q                                                Tollens: Given ~Q  ~P



         beer                  soda                 water                   beer

            17                    23                    23                     19

           P                    ~P                      Q                     ~Q
                  Cheating
• Why was the drinking problem easier?
• The evolution of reciprocal altruism required
  that individuals be able to detect cheaters.

• What is cheating in a social exchange?
  – Taking the benefit without paying the associated
    cost or meeting the requirement.
  – Adaptive logic
    Features of a cheater detection system
    Shouldn’t need to be familiar with the content
    Should use the rules of adaptive logic not necessarily
     formal logic
    Should be sensitive to perspective
    Should be sensitive to costs and benefits
    Should be sensitive to intentional cheating versus
     innocent mistakes
    Should be able to detect cheaters not altruists
      1. Shouldn’t need to be familiar with the problem
                  100
                   90   familiar
                   80   unfamiliar
Percent Correct




                   70
                   60
                                                       Drinking   Cassava
                   50                                    Age       Root

                   40
                   30
                   20
                                        If a yellow
                          If 7 then E     canary,
                   10                    then blue
                                         bananas

                    0
                          Descriptive                 Social Contract
     Adaptive vs Formal Logic
• From an adaptive point of view, is there any
  difference between the following:
  – If you give me your watch, then I’ll give you $10
  – If I give you $10, then you give me your watch


• Is there a difference according to the rules
  of formal logic?
2. Rules of adaptive logic not necessarily formal logic
 • Normal social contract:
              If you take the benefit, then you pay the cost

                          p                       q

   Formal logic violation:
   Adaptive logic violation:

 • Switched social contract:
              If you pay the cost, then you take the benefit

                      p                       q

  Formal logic violation:
  Adaptive logic violation:
   2. Rules of adaptive logic not necessarily formal logic
• Normal social contract:
     If you are drinking beer, then you must be over 21.

                     p                          q
 Formal logic violation:
 Adaptive logic violation:

• Switched social contract:
         If you are over 21, then you (can) drink beer.

                 p                          q

 Formal logic violation:
 Adaptive logic violation:
2. Rules of adaptive logic, not necessarily formal logic
Standard Social Contract:
If you take a benefit, then you pay the cost
Switched Social Contract:
If you pay the cost, then you (can) take the benefit

           Benefit     Benefit not    Cost      Cost not
           accepted    accepted       paid      paid

Standard     P            ~P           Q         ~Q



Switched     Q            ~Q           P         ~P
• How do subjects perform on the
  switched social contract?
  – __% pick Q and ~P which is the correct
    adaptive response but the incorrect logical
    response.
• So it looks as if people follow an
  adaptive logic, not modus ponens or
  modus tollens.
• This makes sense if people are looking
  for cheaters and not just logic violators.
3. Should be sensitive to perspective
• You would expect reasoning mechanisms
  to be sensitive to perspective.

• Example:
  – If an employee gets a pension, then he
    must have worked more than 10 years.
Rule:
 If an employee gets a pension then he
 must have worked more than 10 years.

         Gets     Doesn’t get      Gets        Gets
      a pension    a pension    a pension   a pension


                                Worked      Worked
         8           24          30 yrs      2 yrs


What counts as a violation to this rule for the employer?
What counts as a violation to this rule for an employee?
       Perspective Matters!
• Depends on perspective!
• This would not follow from the rules of
  formal logic.
• We possess circuits that follow an
  ecological rationality.
    Features of a cheater detection system
   Shouldn’t need to be familiar with the content
   Should use the rules of adaptive logic not necessarily
    formal logic
   Should be sensitive to perspective
   Should be sensitive to costs and benefits
   Should be sensitive to intentional cheating versus
    innocent mistakes
   Should be able to detect cheaters not altruists
        Dissociations as evidence for
         specialized neural circuitry
Daffy has a lesion
  to a particular
  brain region.
  Test him and a
  control (bugs)
  on two different
  tasks (A & B).


                Performs well on A Performs well on A
                Performs well on B Does not perform well on B
  Neuropsychology of Social Exchange
• Are there areas of the brain that have been
  associated with the ability to reason about
  social exchange and cheaters?
• To look at impairments in the brain, good to
  look at two abilities that are hypothesized to
  use different reasoning circuits.
• Double dissociations
Additional reasoning procedures
• We have been talking about reasoning
  about cheating in a social context
• Also reasoning about precautions:
  – If you handle blood, then you wear gloves

               Did not
                                    Did not
    Handled    Handle     Wore
                                     Wear
     Blood      Blood     Gloves
                                    gloves


      p          ~p        q          ~q
                 Same circuits?
• Are there specialized circuits for reasoning about
  social contracts?
• Hypothesis 1:
  – No specialized circuits: general reasoning abilities
  – Should see either poor performance on both or intact
    performance on both
• Hypothesis 2:
  – Yes, there are specialized circuits for reasoning about
    social contracts.
  – Should see poor performance on social contracts but
    intact performance on precautions
• RM suffered a bicycle
  accident in 1974, when
  he was 25.
• Damage to the medial
  OFC and anterior
  temporal cortex.
• Gave RM social
  contract problems –
  only got 39% correct.
  This is in contrast to
  control subjects who
  got >65%.
• However, he did fine
  on precautions.
                           Summary
• How do we get altruism between non-relatives?
• Social exchange/ reciprocal altruism is possible.
   – TFT strategy in repeated prisoner’s dilemma
      • Properties: retaliatory and forgiving
      • Iterated (one time  defection)
• Requires:
   – Person recognition, attribute memory, reason about cheating.
• How do we reason about cheating?
   – Do we use general purpose reasoning abilities or specialized
     reasoning ability that are specific for cheating?
• What would a general reasoning ability look like?
   – Modus ponens and modus tollens
• What is cheating?
Adaptive Problem     Altruism toward non-relatives




                       Individual recognition
Cognitive Programs     Person memory
                       Reason about cheating


                       Parts of frontal and
 Neurophysiology         temporal lobes??
• Humans are not the only creatures that
  possess mechanisms designed to
  detect cheaters.
• All organisms that participate in
  cooperative relationships are expected
  to have such mechanisms.
• Let’s look at 4 examples:
 –   spawning in the black hamlet fish
 –   regurgitation of blood by vampire bats
 –   alliances in primates
 –   fig trees
     Cooperation among Vampire Bats
• Common for bats to fail to find
  a blood meal. However, they
  need this blood meal to stay
  alive.
• Blood sharing:
  – A hungry bat will beg for
      food from another lucky bat
      who was able to find a
      blood meal during the
      evening.
• It has been shown
  experimentally that well-fed
  bats will donate blood to
  hungry bats who roost near
  them and are familiar to them.
  These individuals are likely
  ones who in the past have
  donated their extra blood.
                                                               Gains in Trade
                                                               Donor -- give 10% of blood will lose only ~2 hours
Amount of blood gathered


                                                    110
                                                               Recipient -- if given 10% of blood will gain ~20 hours
                           (% of pre-fed body wt)



                                                    100


                                                    90
                                                          D
                                                    80


                                                    70
                                                                        R

                                                          50       40       30       20       10
                                                                             Hours to death
Under what circumstances will
     reciprocity evolve?
• Donors must be able to recognize
  cheats, and refuse to feed previous
  recipients who fail to reciprocate.
• Sufficient pair-wise interactions so that
  there are interchanges of roles and
  therefore net benefits to all donors.
• The benefits of receiving aid must
  outweigh the cost of donating it.
                Fig Wasps
• A very neat story...

				
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