Evolution and Cognition Psych 155

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Evolution and CognitionPsych 155

• Professor Leda Cosmides
• TA Mike Mrazek
• Office hours
• Cosmides Thursdays, 300-430 Psych East 3808,
  Tuesdays 1200-130 HSSB 1010
• Mrazek Thursdays, 245-445pm, Bldg 429, room
  102 (mrazek_at_psych.ucsb.edu)
• Course website http//mentor.lscf.ucsb.edu/course
  /fall/psyc155
• E-res password collide

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Evolutionary Psychology

• an approach to psychology, in which knowledge and
  principles from evolutionary biology are put to
  use in research on the structure of the human
  mind.
• not an area of psychology, like vision,
  reasoning, or social behavior. EP is a way of
  thinking about psychology that can be applied to
  any topic within it.

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• 1859
• Charles Darwin (naturalist, biologist) publishes
  On the origin of species by means of natural
  selection
• 1890
• William James (psychologist, philosopher)
  publishes Principles of Psychology
• Says Debauch your mind!
• Make the natural seem strange!

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Charlie task (Baron-Cohen, 1995)
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On making the natural seem strange...

• "It takes...a mind debauched by learning to carry
  the process of making the natural seem strange,
  so far as to ask for the why of any instinctive
  human act. To the metaphysician alone can such
  questions occur as Why do we smile, when
  pleased, and not scowl? Why are we unable to talk
  to a crowd as we talk to a single friend? Why
  does a particular maiden turn our wits so
  upside-down? The common man can only say, Of
  course we smile, of course our heart palpitates
  at the sight of the crowd, of course we love the
  maiden, that beautiful soul clad in that perfect
  form, so palpably and flagrantly made for all
  eternity to be loved! And so, probably, does each
  animal feel about the particular things it tends
  to do in the presence of particular objects. ...
  To the lion it is the lioness which is made to be
  loved to the bear, the she-bear. To the broody
  hen the notion would probably seem monstrous that
  there should be a creature in the world to whom a
  nestful of eggs was not the utterly fascinating
  and precious and never-to-be-too-much-sat-upon
  object which it is to her. " (William James,
  1890)

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A dog compliment...
Making the natural seem strange... Cartoonist
Gary Larson
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Psychology Reverse Engineering

• Engineers design a circuit that can solve a
  particular problem
• Reverse engineering what does this circuit do,
  and how does it work?
• Psychology reverse engineering
• Brains full of circuits
• What problem does each solve, and how does it
  work?

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Back to basics

• Five basic points that organize the course...

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Principle 1

• The brain is a physical system. It functions as
  a computer. Its circuits are designed to generate
  behavior that is adaptive given your
  environmental circumstances.

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Brain is an information-processing device
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Brains generate movement (behavior) regulate
physiology

• Organisms that do not move, do not have brains.
• Sea squirt sometimes has a brain!

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Purpose of brain to generate behavior that is
appropriate to your environmental circumstances

• But what does appropriate mean??

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Principle 2

• Our neural circuits were designed by natural
  selection to solve problems that our ancestors
  faced during our species evolutionary history.

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Appropriate?? Dung flies versus you...
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What counts as appropriate differs for each
species

• People say Behavior is the product of the
  environment
• The environment made me do it!
• BUT Environments do not, in and of themselves,
  specifiy what counts as appropriate behavior

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Environments alone do not determine behavior

• Which behavior a stimulus gives rise to is a
  function of the neural circuitry of the organism
• In principle, brain could be designed to link any
  environmental input to any given behavior
• Yum yum dung!

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Natural selection designs circuitry

• Natural selection
• For now eat dung and die principle
• Circuitry (programs) designed to solve adaptive
  problems
• Adaptive problems
• Recurred during evolution of a species
• Their solution affected reproductionhowever
  indirect the causal chain may be

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Principle 3

• Consciousness is just the tip of the iceberg
  most of what goes on in your mind is hidden from
  you. As a result, your conscious experience can
  mislead you into thinking that our circuitry is
  far simpler that it really is. Most problems
  that you experience as easy to solve are actually
  very difficult to solve -- they require very
  complicated neural circuitry.

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Seeing feels simple, but isnt...

• You see with your brain
• Different areas for
• Shape
• Motion
• Direction of motion
• Distance
• Color
• Identification of humans
• Recognizing individual faces
• etc

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Intuitions of simplicity can deceive you

• Activities that feel easy, automatic, and
  effortless rarely are from a computational point
  of view
• Produced by a vast array of complex
  information-processing circuitry, whose operation
  is not accessible to your conscious awareness

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Principle 4

• Different neural circuitsdifferent programsare
  specialized for solving different adaptive
  problems.

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Basic engineering principle The same machine is
rarely capable of solving two different problems
equally well
Liver ?
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Different adaptive problems require different
solutions

• Same principle applies to adaptive problems that
  require information-processing
• Choosing food versus choosing mate (!)

Giant chocolate bar?? Or John Tooby??...
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Qualitatively different standards...

• To solve adaptive problem of finding the right
  mate, choices must be governed by qualitatively
  different standards than when choosing the right
  food, right habitat, etc...
• Consequently, brain must be composed of a large
  collection of programs, each specialized for
  solving a different adaptive problem

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Principle 5

• Our modern skulls house a stone age mind.

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Adapted to hunter-gatherer way of life

• Natural selection takes a long time to build a
  mechanism of any complexity
• Millions of years hunting and gathering
• Agriculture first seen 10,000 years ago
• Practised by ½ human population only 5,000 years
  ago
• Modern world an instant in evolutionary time

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Hunting and gathering

• A way of making a living, not a kind of people

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Small nomadic bands of a few families
Hadza people in Tanzania
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Savanna environments
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Deli countermeat runs away from you!
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And others want your meat...
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Working mothersgather with baby
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No police... Just your family and friends for
protection
Yanomamo war partyunusually large one
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Dangers to your children...
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Sophisticated thinkers

• Our evolved programs were not designed to solve
  the day-to-day problems of a modern American
• They were designed to solve the day-to-day
  problems of our hunter-gatherer ancestors
• Not an easy life!
• Often better at solving these problems than
  modern ones

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• Principle 1. The brain is a physical system. It
  functions as a computer. Its circuits are
  designed to generate behaviour that is adaptive
  given your environmental circumstances.
• Principle 2. The brains neural circuits were
  designed by natural selection to solve problems
  that our ancestors regularly faced during our
  species' evolutionary history.

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• Principle 3. Consciousness is just the tip of the
  iceberg most of what goes on in your mind is
  hidden from you. As a result, your conscious
  experience can mislead you into thinking that our
  circuitry is far simpler that it really is. Most
  problems that you experience as easy to solve are
  actually very difficult to solve -- they require
  very complicated neural circuitry.
• Principle 4. Different neural circuits are
  specialized for solving different adaptive
  problems.
• Principle 5. Our modern skulls house a stone age
  mind.

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Psychology is

• The branch of biology that studies
• Brains
• How brains process information
• How the brains information-processing programs
  generate behavior

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When trying to understand any aspect of human
behavior, ask

• Where in the brain are the relevant circuits and
  how, physically, do they work?
• What kind of information is being processed by
  these circuits?
• What information-processing programs do these
  circuits embody?
• What were these programs designed to accomplish
  in a hunter-gatherer context?