The goal of research in evolutionary psychology is to discover
and understand the design of the human mind. Evolutionary
psychology is 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 In this view, the mind is a set of
information-processing machines that were designed by natural
selection to solve adaptive problems faced by our hunter-gatherer
ancestors An evolutionary approach allows one to recognize natural
competences it indicates that the mind is a heterogeneous
collection of these competences and, most importantly, it provides
positive theories of their designs. Evolutionary Psychology
Slide 2
The Standard Social Science Model (SSSM) Both before and after
Darwin, a common view among philosophers and scientists has been
that the human mind resembles a blank slate, virtually free of
content until written on by the hand of experience Over the years,
the technological metaphor used to describe the structure of the
human mind has been consistently updated, from blank slate to
switchboard to general purpose computer, but the central tenet has
remained the same [and] has become the reigning orthodoxy in
mainstream anthropology, sociology, and most areas of psychology
According to this orthodoxy: all of the specific content of the
human mind originally derives from the "outside" from the
environment and the social world and the evolved architecture of
the mind consists solely or predominantly of a small number of
general purpose mechanisms that are content-independent, and which
sail under names such as 'learning,' 'intelligence,' 'imitation,
culture
Slide 3
SSSM versus EP SSSM: Same general-purpose mechanisms govern all
psychological tasks (except basic perception, language), e.g., how
one learns to recognize emotional expressions thinks about incest
acquires ideas and attitudes about friends and reciprocity
Mechanisms of reasoning, learning, and memory operate uniformly
they are content-independent or domain-general. EP: All normal
human minds reliably develop a collection of domain-specific
reasoning and regulatory circuits. These circuits organize the way
we interpret our experiences, inject certain recurrent concepts and
motivations into our mental life, and provide universal frames of
meaning that allow us to understand the actions and intentions of
others.
Slide 4
Principle 1: The brain is a physical system. It functions as a
computer. Its circuits are designed to generate behavior that is
appropriate to your environmental circumstances. Principle 2: Our
neural circuits were designed by natural selection to solve
problems that our ancestors faced during our species' evolutionary
history. The reason we have one set of circuits rather than another
is that the circuits that we have were better at solving problems
that our ancestors faced during our species' evolutionary history
than alternative circuits were. For example, just as natural
selection has shaped dung flies to approach dung, it has shaped us
to avoid it. Five Principles
Slide 5
Principle 2: Our neural circuits were designed by natural
selection to solve problems that our ancestors faced during our
species' evolutionary history. Designed to solve adaptive problems,
i.e., problems that cropped up again and again during the
evolutionary history of a species whose solution affected the
reproduction of individual organisms Obviously, we are able to
solve problems that no hunter- gatherer ever had to solve we can
learn math, drive cars, use computers. Our ability to solve other
kinds of problems is a side-effect or by-product of circuits that
were designed to solve adaptive problems. For example, the fact
that we can surf and skateboard are mere by-products of adaptations
designed for balancing while walking on two legs. Five
Principles
Slide 6
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 simpler that it really is. Most problems that you
experience as easy to solve are very difficult to solve they
require very complicated neural circuitry. Principle 4: Different
neural circuits are specialized for solving different adaptive
problems. A basic engineering principle is that the same machine is
rarely capable of solving two different problems equally well. We
have both screw drivers and saws because each solves a particular
problem better than the other. Five Principles
Slide 7
Principle 5: Our modern skulls house a stone age mind. Natural
selection, the process that designed our brain, takes a long time
to design a circuit of any complexity. The time it takes to build
circuits that are suited to a given environment is so slow it is
hard to even imagine it's like a stone being sculpted by wind-blown
sand. Even relatively simple changes can take tens of thousands of
years. Actually evidence is accumulating in many areas that
selection can occur quickly, at least sometimes. The Environment of
Evolutionary Adaptedness (EEA): Hunter-gatherer (foraging)
societies of the African savanna. Five Principles
Slide 8
Principle 4: Different neural circuits are specialized for
solving different adaptive problems.
Slide 9
T & C: Brains do not use the propositional calculus (or any
other general algorithm) to solve (many) problems. Five
Principles
Slide 10
Reasoning instincts: An example Wason Selection Task: Subject
is asked to look for violations of a conditional rule of the form
If P then Q. Rule: "If a Cambridge resident goes into Boston, then
that person takes the subway. Each card represents one person. One
side of a card tells where a person went, and the other side of the
card tells how that person got there. Indicate only those card(s)
you definitely need to turn over to see if any of these people
violate this rule. Boston & cab cards only ~25% of subjects get
this right!
Slide 11
Reasoning instincts: An example Wason Selection Task: Subject
is asked to look for violations of a conditional rule of the form
If P then Q. People who ordinarily cannot detect violations of
if-then rules can do so easily and accurately when that violation
represents cheating in a situation of social exchange/contract
Rule: "If you are drinking alcohol then you must be 21" 1721
Drinking Beer Drinking Coke Indicate only those card(s) you
definitely need to turn over to see if any of these people violate
this rule. 17 & drinking beer most people get this right!
Slide 12
Reasoning instincts: An example Wason Selection Task: Subject
is asked to look for violations of a conditional rule of the form
If P then Q. Rule: "If a card has an even number on one face, then
its opposite face is red. Which card(s) must be turned over to see
if this rule has been violated. 8 and brown cards only ~25% of
subjects get this right!
Slide 13
Which of the following cards do you need to turn over to either
confirm or falsify the hypothesis that if a card has an even number
on one side, it has a vowel on the other? 1 2 A B Reasoning
instincts: An example Wason Selection Task: Subject is asked to
look for violations of a conditional rule of the form If P then Q.
2 & A cards only ~25% of subjects get this right!
Slide 14
Social contract form again Which of the following cards do you
need to turn over to either confirm or falsify the hypothesis that
If you charge a purchase on your credit card, you must pay the
bill. Person charges purchase Person doesnt charge Person pays bill
Person doesnt pay bill Most people get the right answer! Reasoning
instincts: An example
Slide 15
For altruism without kin selection to work, need reciprocity
Useful to have the payoffs delayed Ill do this for you now if you
agree to do that for me (or my children) later Dont want to make
such deals with cheaters, so its necessary to have a means of
detecting cheaters Conclusion: natural selection for a cheater
detection module! Cheater Detection & Social Contracts
Slide 16
From Descartes on, strong emphasis on unity of mind Flourens
opposition to phrenology Opposition to brain localization in 20th
century: Lashley, Head et al Behaviorists general learning
principles But cognitive psychology has tended to emphasize the
division of the mind into specific processors, responsible for
different cognitive processes Memory, language, object recognition,
etc. Strategies for dissociation designed to separate processing
components functionally (and structurally in neuropsychology)
General Processes vs. Modularity
Slide 17
We may usefully think of the language faculty, the number
faculty, and other mental organs, as analogous to the heart or the
visual system or the system of motor coordination and planning....
In short, there seems little reason to insist that the brain is
unique in the biological world, in that it is unstructured and
undifferentiated, developing on the basis of uniform principles of
growth or learningsay those of some learning theory, or some
yet-to-be- conceived general purpose learning strategythat are
common to all domains (1980, p. 3). Chomskys mental organs
proposal
Slide 18
Distinction between horizontal and vertical modules. Vertical
modules: domain-specific mandatory in their operation allow only
limited central access to the computations of the modules fast,
informationally encapsulated have shallow outputs associated with
fixed neural architectures exhibit characteristic and specific
breakdown patterns exhibit a characteristic pace and sequencing in
their development Fodors Modularity of Mind
Slide 19
informationally encapsulated Fodors Modularity of Mind
Slide 20
Evidence for top-down (as opposed to bottom-up) processing
Speech processing Word recognition based on acoustic and phonetic
information alonesyntax and semantics have no influence Evidence
from shadow speechpeople restore the correct word despite
distortions, which they do not do when the sound is presented in
isolation Controversial case: McGurk Effect Challenges to Fodorian
Modularity
Slide 21
Seeing someone say ga while hearing ba results in perception of
intermediate sound. Could be entirely within language module (motor
theory of speech perception) Massaro: rather invokes more general
processing: integration of information and top-down as well as
bottom-up processing McGurk Effect
Slide 22
Seeing someone say ga while hearing ba results in perception of
intermediate sound. Could be entirely within language module (motor
theory of speech perception) Massaro: rather invokes more general
processing: integration of information and top-down as well as
bottom-up processing McGurk Effect
http://www.youtube.com/watch?v=G-lN8vWm3m0
Slide 23
We have all these specialized neural circuits because the same
mechanism is rarely capable of solving different adaptive problems.
For example, we all have neural circuitry designed to choose
nutritious food on the basis of taste and smell circuitry that
governs our food choice. But imagine a woman who used this same
neural circuitry to choose a mate. She would choose a strange mate
indeed (perhaps a huge chocolate bar?). To solve the adaptive
problem of finding the right mate, our choices must be guided by
qualitatively different standards than when choosing the right
food, or the right habitat. Consequently, the brain must be
composed of a large collection of circuits, with different circuits
specialized for solving different problems. You can think of each
of these specialized circuits as a minicomputer that is dedicated
to solving one problem. Evolutionary Psychology: Modules all the
way through
Slide 24
Such dedicated mini-computers are sometimes called modules.
There is, then, a sense in which you can view the brain as a
collection of dedicated mini-computers a collection of modules.
There must, of course, be circuits whose design is specialized for
integrating the output of all these dedicated mini-computers to
produce behavior. So, more precisely, one can view the brain as a
collection of dedicated mini-computers whose operations are
functionally integrated to produce behavior. Cosmides & Tooby,
Evolutionary Psychology: A Primer Evolutionary Psychology: Modules
all the way through
