Chapter Eight

1
Chapter Eight

• The Evolutionary Approach Change Over Time

2
Evolutionary Psychology

• Evolutionary Psychology (EP) describes how our
  early environment produced our current mental
  abilities.
• This environment was the the Pleistocene era,
  approximately two million years ago, referred to
  as the Environment of Evolutionary Adaptation
  (EEA).
• Evidence to support evolutionary hypotheses comes
  from archeological records, hunter-gatherer
  societies, between- and within-species
  comparisons, and experimentation.

3
Natural selection

• EP relies on Darwins (1859) theory of natural
  selection. It requires three elements
• Variation in traits within a species.
• The passing of genetic material from one
  generation to the next, called inheritance.
• Selection, which is a change in the environment
  that favors one trait over another.

4
Evolved psychological mechanisms

• EP views the mind as a collection of special
  purpose devices or a Swiss army knife.
• Each device evolved under selection pressures to
  solve a specific problem.
• These mechanisms can be considered as modules.
• This is in contrast to the traditional notion of
  mind as a general purpose processor.

5
Properties of an evolved psychological mechanism

1. Solves a specific adaptive problem.
2. Takes in only a narrow band of information.
3. Informs the user of the type of problem.
4. Produces a response through a set of decision
   rules.
5. The response can be a physiological reaction,
   information to another mechanism, or a behavior.
6. The response is intended to provide a solution to
   the problem.

6
Evolution and categorization

• We form concepts in a graded, continuous fashion,
  not all or none.
• Natural categories are also continuous. The mind
  mimics this organization.
• This allows us to generalize our knowledge from
  one category to another.
• Concepts are organized around representative
  members of a class, the typicality effect.

7
Which looks more like a bird?
8
Evolution and memory

• We should have a better memory for information we
  are exposed to more often.
• This is because it is more relevant to our
  survival.
• Recall for words is proportional to their
  frequency of occurrence (Anderson and Schooler,
  1991).

9
The Wason selection task - hard version

• You have been hired as a clerk. Your job is to
  make sure that a set of documents is marked
  correctly, according to the following rule "If
  the document has an E rating, then it must be
  marked code 4." You have been told that there are
  some errors in the coding of the documents, and
  that you need to find the errors. Each document
  has a letter rating on one side and a numerical
  code on the other. Here are four documents. Which
  document(s) do you need to turn over to check for
  errors?

10
The Wason selection task - easy version

• You have been hired as a bouncer in a bar and you
  must enforce the following rule "If a person is
  drinking vodka, then he must be over twenty years
  old." The cards above have information about four
  people in the bar. One side of each card lists a
  person's age and the other side shows what he or
  she is drinking. Which card(s) do you need to
  turn over to be sure no one is breaking the law?

11
Evolution and logical reasoning

• The bouncer problem is easy because it involves
  cheater-detection.
• In the EEA it was important to detect who might
  be cheating because in small groups with limited
  resources it might mean less for you (Cosmides
  and Tooby, 1992).
• The logic module thus works only in this context,
  implying logic is not domain general.

12
Evolution and judgment under uncertainty

• Uncertain judgments occur when we make a decision
  without complete information.
• Most everyday decisions in life are like this.
• In such cases, we often rely on heuristics.
• But heuristics can lead us to commit fallacies, a
  misunderstanding of statistical rules.

13
Fallacies

1. Base-rate fallacy. Ignoring base rates.
2. Conjunction fallacy. Ignoring the conjunction
   rule.
3. Gamblers fallacy. Ignoring independent outcomes.

14
Evolution and language

• Language may have evolved to promote social
  bonding (Dunbar, 1996).
• It allows for complex coordinated social
  behavior. Examples improvements in hunting,
  foraging, and childcare.
• It may also play a role in sexual selection.

15
Evolution and sex differences

• Attributed to a sexual division of labor in which
  men hunted and women gathered.
• Hunting may have fostered increased spatial
  ability in men.
• Gathering may have promoted increased verbal
  abilities in women.
• But above distinction is too broad. Women are
  better at object location memory.

16
Evolutionary Computing

• Thinking may utilize evolutionary principles.
• Steps in problem solving
• Generate candidate solutions.
• Evaluate their fitness.
• Select solutions with high fitness values.
• Generate new solution offspring by genetic
  combination.
• Repeat steps 2-4.

17
Artificial Life

• The study of manmade systems that behave in ways
  characteristic of natural living systems
  (Langton, 1989).
• Computer creatures are created through
  evolutionary rules. They navigate, seek out prey,
  and avoid predators in a virtual environment.
• Complex adaptive behaviors emerge including
  parasitism, symbiosis, and flocking.

18
Neural Darwinism

• Application of evolution to neural learning
  (Edelman, 1989).
• Initial growth of neural structures during
  development.
• Interaction with environment causes differential
  modification of synaptic strengths.
• Reentrant signaling between neural groups.

19
Evaluating the evolutionary approach

• Novel biological function need not arise to
  service survival or reproduction. Other
  mechanisms
• Exaptation or neutral drift. Random mutation.
• Molecular drive. Copies of genes mutate.
• Idea of a spandrel (Gould, 2000). Byproducts of
  adaptations.

20
Spandrels in architecture