CHAPTER EIGHT The Evolutionary Approach: Change Over Time

Natural Selection  EP relies on Darwin ’ s (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.

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.

Comparative Cognition  The cross-species study of cognitive ability.  Each species is adapted to its ecological niche.

Animal Memory  Object permanence is the ability to know that an object still exists even though it cannot be perceived.  Dogs have this capacity. They will look for a toy that has been hidden behind boxes (Gagnon & Dore, 1994).  It requires memory and is adaptive for locating prey that have disappeared behind obstacles.

Animal Memory  Memory is also useful for remembering where you have already searched so you don’t have to look in the same place twice.  The Hawaiian honeycreeper bird can remember which flowers it has already fed from.  The nutcracker bird can store up to 33,000 pine nuts in 6,000 different sites in the summer and remember them when it comes back in the winter and spring!

Animal Problem Solving  Kohler’s chimps and insight learning  Transitive inference is like deductive reasoning. It involves knowing that if A is bigger than B and B is bigger than C, then A is bigger than C.  Squirrel monkeys can deduce which colored box contains a peanut (McGonigle & Chalmers, 1977).  Pigeons and rats can also solve transitive inference problems (Davis, 1992).

Comparative Neuroscience  Involves comparing the brains of different animal species.  Do smarter animals have bigger brains?  We must adjust for body size. The cephalization index does this.  But factors other than intelligence influence brain size. Birds have small brains because they need to be light to fly. Dolphins have larger brains because water can support a large body weight.

The Cephalization Index

Comparative Neuroscience  Also, not every part of a brain “does” cognition.  The hindbrain mostly regulates basic physiological function.  The cortex, especially the neocortex is the part most closely linked to cognition.  The neocortex is 80% of total brain volume for humans. In primates it is 50% and in rodents it is 30%.

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.

Evolutionary Psychology  The traditional view in cognitive psychology is that brains are general purpose processor. They can solve any problem of a given type.  The evolutionary view is that specific cognitive abilities have developed to solve specific adaptive problems. These abilities are referred to as evolved psychological mechanisms.  Cosmides and Tooby (19920 refer to the evolutionary brain as a “Swiss Army Knife”.

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.

Which Looks More Like a Bird?

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).

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?

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?

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.

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.

Fallacies  Base-rate fallacy. Ignoring base rates. Example: Jack the lawyer/engineer.  Conjunction fallacy. Ignoring the conjunction rule. Example: Linda the bank teller.  Gambler ’ s fallacy. Ignoring independent outcomes. Example: gambling.

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.

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.

Behavioral Economics  The study of economic decision making and the factors that affect it.  Classical view is that people are rational and always make choices that increase their money or value.  In reality the way we think about money is affected by heuristics and evolution, just as we discussed in the prior section.

The Ultimatum Game  How would you split a $1,000 with someone else?  Your partner would refuse to accept up until a split of about (Camerer, 2003).  Why turn down free cash?  Because the split is perceived as unfair. In small societies reciprocal altruism is the rule. Favors are expected to be returned. If you cheat someone now, they will probably cheat you later.

Loss Aversion  You are on a team of experts that must decide what course of action to take in preventing a flu outbreak.  Program A. 200 people will be saved.  Program B. There is a one-third probability that 600 people will be saved, and a two-thirds probability that no people will be saved.  A full 72% of the participants in one experiment chose option A.

Loss Aversion  Now consider the following re-wording of the question:  Program C. 400 people will die.  Program D. There is a one-third probability that nobody will die, and a two-thirds probability that 600 people will die.  The outcomes in this second case are identical to that in the first, yet now the responses are reversed. Seventy eight percent now chose program D over program C.

Framing Effects  Option A. TheMePhone is available at Awesome Electronics for $100; five blocks away at DigiData it is at half price for only $50. Would you make the short trip to save the $50?  Option B. PowerPurchase offers the NetBook for $1,000; five blocks away it can be had for $950 at CircuitCrazy. Would you make the short trip to save the $50?  The majority of people when presented with this problem prefer option A.

Mental Accounting  We put money into different categories depending on the amount. We reason differently about smaller sums than we do larger ones.  $50 seems like more money when compared to $100 than to $1,000.

The Endowment Effect  One group is given a choice of investments. They chose based on how risk averse they are.  In a second condition the same group is already given an investment.  They are more likely to stick with what they were given. 47% stayed with it, compared to 32% of those who had chosen it earlier.

The Sunk-Cost Fallacy  We tend to stick with those things we’ve already put a lot of time, energy, or money into.  Example: Chris prefers his “old clunker” car because he just spent a $1,000 to fix it.  This can be irrational, since the old car is more likely to break down and cost more money in the future compared to a better car.

Evaluating the Evolutionary Approach  Novel biological function need not arise to service survival or reproduction. Other mechanisms: 1. Exaptation or neutral drift. Random mutation. 2. Molecular drive. Copies of genes mutate. 3. Idea of a spandrel (Gould, 2000). Byproducts of adaptations.

Spandrels in Architecture

Interdisciplinary Crossroads: 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.