Evolutionary psychology Cos Mides

7/23/2019 Evolutionary psychology Cos Mides

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Evolutionary psychology

Cognitive instincts for cooperation,institutions & society

Leda Cosmides

Center for Evolutionary Psychology

and Department of PsychologyUniversity of California, Santa Barbara

www.psych.ucsb.edu/research/cep


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Four innovations leading to evolutionary psychology

1. The cognitive revolution provided a precise language for

describing mental mechanisms: as programs that processinformation.

2. Advances in paleoanthropology, hunter-gatherer studies andprimatology provided data about the adaptive problems ourancestors had to solve to survive and reproduce and theenvironments in which they did so.

3. Research in animal behavior, linguistics, and neuropsychologyshowed that the mind is not a blank slate, passively recordingthe world. Organisms come factory-equipped with knowledgeabout the world, which allows them to learn some relationships easily,and others only with great effort, if at all.

4. The revolution that placed evolutionary biology on a morerigorous, formal foundation of replicator dynamics & gametheory, clarifying how natural selection works, what counts as anadaptive function, and what the criteria are for calling a trait anadaptation. (George Williams, W. D. Hamilton, John Maynard Smith, RichardDawkins)

ethology: 2, 3 sociobiology: 2, 3, 4 ev psych: 1,2,3,4


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Evolutionary psychology

Human Nature: the set of species-typical information-

processing programs that reliably develop inthe human brain (i.e., the architecture of the

human mind)

Key insight:

The programs comprising the human mind

were designed by natural selection to solve theadaptive problems faced by our hunter-gatherer ancestors. Knowing this helps onediscover their structure.


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Evolutionary psychology: 5 step research program

Identify an enduring adaptive problem our hunter-

gatherer ancestors faced (e.g., cooperating with others; keeping trackof information relevant to foraging; avoiding predators). This involvescombining results from evolutionary game theory, hunter-gathererstudies, paleoanthropology, primatology, etc.

Do a task analysis, derive hypotheses about cognitive

programs.What design features would a program need to have tosolve that adaptive problem well? Use this task analysis to derivehypotheses about the structure of the relevant programs.

Test hypotheses in laboratory: Using standard experimentalmethods from cognitive and social psychology (and experimental

economics), see if there is evidence that the proposed programs exist(This includes tests against alternative computational designs thathave been proposed)

Identify the programs neurological basis (as anothercheck of its reality)

Test cross-culturally (field site in Ecuadorian Amazon)


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Causal connections between the 4 developments

The brain is an evolved computer (#1), whoseprograms were sculpted over evolutionary timeby the ancestral environments and selection

pressures experienced by the hunter-gatherersfrom whom we are descended (#2 and #4).

Individual behavior is generated by thiscomputer, in response to information that the

person experiences (#1).

Although the behavior these programs generate

would, on average, have been adaptive(reproduction-promoting) in ancestralenvironments, there is no guarantee that it will beso now. Modern environments differ importantlyfrom ancestral ones (esp. social environments).


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Causal connections between the 4 developments

The brain must be comprised of many differentprograms, each specialized for solving a differentadaptive problem our ancestors facedi.e., themind cannot be a blank slate (#3).

This can be shown by using results from replicator

dynamics (#4) to define adaptive problems, and thencarefully dissecting the computational requirements ofany program capable of solving those problems

(e.g., a program that is well-designed for choosingmates will embody different preferences and inferencesthan one that is well-designed for choosing foods).

If you want to understand human culture andsociety, you need to understand these domain-specific programs.


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Reasoning instincts

Complexly specialized for solving anadaptive problem

Reliably develop in all normal human beings

Develop without any conscious effort Develop without any formal instruction

Applied without awareness of their

underlying logic Distinct from more general abilities to

process information or behave intelligently

after Pinker, 1994


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Charlie task (Baron-Cohen, 1995)


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Do we have cognitive instincts regulating

cooperation?

If so, how do they work?

2-person cooperation (social exchange,

trade, reciprocation)

N-person cooperation (collective action)


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Karl Marx believed...

Extant hunter-gatherers (and by extension, our

ancestors) lived in a state of primitive communism: where all labor was accomplished through collective

action, &

sharing was governed by the decision rule, from each

according to his ability to each according to his need.

The overthrow of capitalism would bring forth an

economically advanced society with similar

properties:

abolish private property and all labor will once again be

accomplished through collective action and, because the

mind reflects the material conditions of existence, the

huntergatherer communal sharing rule will emerge

once again and dominate social life.


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Based on Marxs theory...

20th century institutions and laws governingproperty, the organization and compensation

of labor, the regulation of manufacturing and

trade, and the legitimacy of consent and

dissent were changed across the planet

China, the former Soviet Union, Cambodia, Cuba,

North Korea, Vietnam, and Eastern Europe.

Profound impact on the lives of the citizens ofthese nations, although not the utopian ones

Marx had envisioned.


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Was Marx right?

In this light, it is reasonable to ask whetherMarxs view of huntergatherer labor andsharing rules was correct.

If not, what cognitive programs regarding

cooperation did the selection pressures

endemic to hunter-gatherer life build?


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Hunter-gatherer life:

Cooperative, but NOTan orgy of

indiscriminate cooperation

Several alternative sharing rules Even within the same cultural group

Triggers for alternative sharing rules:

Perception of variance due to LuckversusEffort


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Alternative sharing rules

Luck versus effort as triggers for alternative

sharing rules

Meat: Variance high & due to luck

Risk pooling to deal with frequent reversals of

fortune

Closest to sharing rule From each according to hisability to each according to his need

Gathered foods: Variance low & due to Effort Share within family

Share via reciprocation

Other goods: reciprocation /trade


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Evolved programs for risk pooling:

What activates them?

Requires cue activated programs

In this situation: Is luck causing reversals

of fortune? Or not? Same psychology in Japan, USA

Windfall due to luck:

More likely to share More likely to demand shares from the

lucky (redistribution)


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Risk pooling: A grammar of sharing

1 & 2 sound human:

1. If hes the victim of an unlucky tragedy,then we should pitch in to help him out.

2. If he spends his time loafing and living off

of others, then he doesnt deserve our help.

*3 & *4 sound weird:

*3. If hes the victim of an unlucky tragedy,then he doesnt deserve our help.

*4. If he spends his time loafing and living offof others, then we should pitch in to help

him out.


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Risk pooling psychology shapes debate now

High variance due to luckband-widesharing seems good and proper

Cultural transmission: shaped by samesharing rules

Political debate on homelessness

Argument about bad luck or low effort, notabout what follows from that

Rent controlhelping?? In modern context, what social unit do we

interpret as our band? Community?State? Nation?


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Social Exchange (2 agent cooperation)

Cooperation for mutual benefit Reciprocity, reciprocal altruism, tit for tat

Trivers, 1971, Axelrod & Hamilton, 1981,

Axelrod, 1984 Usually modeled as a repeated Prisoners

Dilemma

Tradeis social exchange without a delay between

favors given and received

Game theory: reciprocation cannot evolve

without a means of detecting and avoiding

cheaters


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Reasoning instincts: Social exchange

The human mind contains a neurocognitiveadaptation that is functionally specialized

for reasoning about social exchange, which

includes a subroutine for detecting cheaters.

This neurocognitive system reliably

develops in the human cognitive

architecture in a species-typical manner. (Itis one component of human nature).

It is a cognitive foundation of trade.

Cosmides & Tooby, 2005. Neurocognitive adaptations for social exchange In Handbook ofEvolutionary Psychology; Cosmides & Tooby 1992. InThe Adapted Mind.


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When institutions prohibit and sanction the

use of coercion and fraud...

Private trade can promote social welfare (Adam Smith)

Mind is well-equipped to compute own preferences

No unbounded rationality problems:The system uses

limited information about values that is only availablelocally (what do I want, what am I willing to do) andsimple heuristics (choose the alternative that is betterfor me/us) to progressively move to ever-increasinglevels of social welfare.

Each individual agrees to trade only if they believe theywill be better off

Trade picks out benefit-benefit interactions; disallows

taking benefit at someone elses expense


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Puzzle: aside from economists...

Removing restrictions on private trade is rarelyproposed as a means of advancing generalsocial welfare... Why?

Perhaps because the psychology of socialexchange produces intuitions about privategain rather than public good...

Why is collectivism so appealing?

Perhaps because the psychology ofcollective action produces intuitions aboutenhancing welfare of the group


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Cooperation with >2 people

The psychology of collective action

Organize labor as a collective action?


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Organizing labor as a collective action?

Collective action / coalitional cooperation:

3+ individuals cooperate to achieve a common goal

and share the resulting benefits

Hunter-gatherers engage in collective action (with

non-kin):

In intergroup conflict (small-scale warfare)

Resource acquisition

Big game hunting Shelter building (less common)

Cognitive foundation of teamwork, busineses,

organizational behavior


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in repeated 2-person cooperation and exchange, if

the other person cheats you, you can protect

yourself by no longer interacting with cheater

in n-person collective action, this is no longer an

effective choice: to distance oneself from the free-rider, one must distance oneself from the

cooperating group

solution: keep the group, punish the free-riders

evolved solution: irrational punitive sentimentsagainst free-riders

More than 2: The problem of cheating


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Communism: Organizing labor as a

collective action

Do people freely contribute to collective

actions that produce public goods?

From each according to his ability toeach according to his need? (no)

Is punishment needed to stabilize

contributions to collective actions? (yes) Is there a dark side to collective action?


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Public goods games:

Experimental economics

Group of 4. Number of sessions known.

Each person gets an endowment. Can keepall or donate any fraction to common pool

Anything in common pool is multiplied Whatever is in common pool is divided

EQUALLY; each member of the group gets

an equal share Rational choice predicts:

100% free riding

No one pays to punish free riders


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Paired with partners Fehr & Gachter, 2000


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Fehr & Gachter, 2000Paired with strangers


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Masclet, Noussair, Tucker, Villeval, 2003Disapproval points!


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What predicts when individual

contributors punish free riders?

Negative deviation from own high

contribution

How much less is he contributing thanme?

Negative deviation from group average

How much less is he contributing than thegroup average?

Masclet, Noussair, Tucker, Villeval, 2003


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Punishment increases contributions from

free riders

Masclet, Noussair, Tucker, Villeval, 2003


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When punishment is not possible,

collective action unwinds...

People monitor how much others are

contributing

Pay special attention to the group average

If I am contributing more than group

average, I rachet back my contribution to

group average

Over iterations, the collective action

unwinds, eventually it fails


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Coercion: A predictable effect?

Sufficiently large collective actions:

decouple reward from effort, initiating a process ofdeclining effort by some,

which stimulates matching withdrawal by others.

This free riding and the dwindling participation itengenders:

intensifies punitive sentiments toward

undercontributors, culminating in social systems organized around coercion and

punishment (where rulers can deploy it) or

dissolution of the collective action (where they

cannot).


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Is large scale collective action a good

thing? The design of institutions

Farms, factories, restaurantsall involvemulti-individual cooperation and hencecollective action.

Should these projects be organized aspublic goods (everyone benefits equally,regardless of their level of participation),

OR Should payoffs be organized such that effort

is rewarded and free riding is punished?


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The iterative rachet effect...

Agricultural policy in the former Soviet Union

The state nationalized farmland and forced farmersto organize their labor as a collective action.

But they allowed 3% of the land on collective farmsto be held privately

This 3% of land produced 45% to 75% of all thevegetables, meat, milk, eggs, and potatoesconsumed in the Soviet Union

The quality of land on the collectively-held plotswas the same

Iterative ratchet effect. People shifted theirefforts away from the collective to the private

plots.

Without these private plots, it is likely that the

people of the Soviet Union would have starved.


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Mismatch: Modern versus ancestral

world Our minds are equipped with programs that were

evolved to navigate a small world of relatives,friends, and neighbors, not for cities and nationstates of thousands or millions of anonymous

people. Certain laws and institutions satisfy the moral

intuitions these programs generate.

But because these programs are now operatingoutside the envelope of environments for whichthey were designed, laws that satisfy the moralintuitions they generate may regularly fail to

produce the outcomes we desire and anticipate


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Mismatch: Modern versus ancestral

world

Even worse, they may cause us to overlook policiesthat have the consequences we wish.

These mental programs so powerfully structure our

inferences that certain policies may seem self-evidently correct and others self-serving or

immoral

But modern conditions often produce outcomes

that seem paradoxical to our evolved programs:venal motives can be the engines that reliably

produce humane outcomes, and what seem like

good intentions can make a hell on earth


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So: Go save the world!

But do it using what you know about humannature!



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Thank you!

Kin detection: altruism &incest aversion

Computational approachto motivation: anger, guilt

Coalitional psychology(us versus them)

Collective action & freeriders

Judgment underuncertainty

Predator-prey reasoning

Visual attention to

animals

Precautionary reasoning Moral sentiments

Memory systems

Scope hypothesis Personality system, self

Center for Evolutionary Psychologywebsite:


Some other research at the CEP:


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Reasoning instincts for social exchange?

Cooperation for mutual benefit(2 agent cooperation)

Reciprocity, reciprocal altruism, tit for

tat

Trivers, 1971, Axelrod & Hamilton, 1981,

Axelrod, 1984

Tradeis social exchange without a

delay between favors given and received


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Evidence that social exchange is a long-

enduring adaptive problem

Universal

Highly elaborated in all cultures

Reciprocal gift-giving, food sharing, market

pricing, symbolic, implicit Not a recent cultural invention

No evidence of point of origin, of having

spread by contact, of being absent in any

culture Paleoanthropological evidence

Hunter-gatherer archaeology: 2 million

years old

Primate evidence 5-30 million years old?

Conclusion:

Social

exchange is an

ancient,pervasive, and

central part of

human social

life


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Evolutionary game theory

Social exchange: Usually modeled as arepeated Prisoners Dilemma

Game theory result:

Neural programs causing individuals of

a species to engage in social exchange

CANNOT EVOLVE unless theyinclude a means of detecting and

avoiding cheaters


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Social contracts

Example:Ifyou give me your watch, I will give you $100

A social contract is a situation in which one isobligated to satisfy a requirement of somekind, in order to be entitled to a benefit.

The requirement is imposed because itssatisfaction creates a situation that benefitsthe party that imposed it


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...should be content-dependent:

a cheater is someone who illicitly took a

benefit

i.e., a person who took the benefit

withouthaving satisfied the requirement.(regardless of logical category)

The mind's definition of cheating ...


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Which events count as cheating depends on

whose perspective you take

Ifyou give me your watch, I will give you $100If P then Q

I cheated you if:I accepted your watch BUT I did not give you $100

P and not-Q

You cheated me if:You accepted my $100 BUTyou did not give me your watch

Q and not-P

Note: definition of logical violation is content-

independent: Given If P then Q, always P & not-Q

(no matter what these refer to)


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Conditional reasoning & reciprocation

Reciprocation is, by definition, social behaviorthat is conditional:

you deliver a benefit conditionally

i.e., conditional on the other person doingwhat you required in return

Understanding it requires conditional

reasoning.

Therefore, investigations of conditionalreasoning can serve as a test case.


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What kind of reasoning instincts govern

how we think about social exchange?

Formal logic has rules for conditional reasoning

In reasoning about social exchange, does the

human mind apply:

Reasoning procedures that embody formal logic

Domain general, content-free

Or reasoning procedures that are specialized for

social exchange Domain specific, content-rich


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Conditional reasoning

Is the cognitive machinery that causes good

conditional reasoning generaldoes it operatewell regardless of content? (blank slate-typetheory)

OR

Do our minds include cognitive machinery that isspecialized for reasoning about social exchange?

alongside other domain-specific mechanisms, eachspecialized for reasoning about a differentadaptive

domain involving conditional behavior

TheWason selection taskis a test of conditionalreasoningwhich we used to test these hypotheses.


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Ebbinghaus disease was recently identified and is not yet well understood. So an international

committee of physicians who have experience with this disease were assembled. Their goal was to

characterize the symptoms, and develop surefire ways of diagnosing it.

Patients afflicted with Ebbinghaus disease have many different symptoms: nose bleeds, headaches,

ringing in the ears, and others. Diagnosing it is difficult because a patient may have the disease, yet not

manifest all of the symptoms. Dr. Buchner, an expert on the disease, said that the following rule holds:

If a person has Ebbinghaus disease, then that person will be forgetful.

If P then Q

Dr. Buchner may be wrong, however. You are interested in seeing whether there are any patients whose

symptoms violate this rule.

The cards below represent four patients in your hospital. Each card represents one patient. One side of

the card tells whether or not the patient has Ebbinghaus disease, and the other side tells whether or not

that patient is forgetful.

Which of the following card(s) would you definitely need to turn over to see if any of these

cases violate Dr. Buchner's rule: If a person has Ebbinghaus disease, then that person will beforgetful. Don't turn over any more cards than are absolutely necessary.

has

Ebbinghaus

disease

does not have

Ebbinghaus

disease

is forgetful is not forgetful

P not-P Q not-Q

Only 26% answer P & not-Q

T h d h h i ll d b i h i


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Teenagers who dont have their own cars usually end up borrowing their parentscars. In return for the privilege of borrowing the car, the Goldsteins have given theirkids the rule,

If you borrow my car, then you have to fill up the tank with gas.

If P then QOf course, teenagers are sometimes careless and irresponsible. You are interested inseeing whether any of the Goldstein teenagers broke this rule.

The cards below represent four of the Goldstein teenagers. Each card represents oneteenager. One side of the card tells whether or not a teenager has borrowed the

parents car on a particular day, and the other side tells whether or not that teenagerfilled up the tank with gas on that day.

Which of the following card(s) would you definitely need to turn over to see ifany of these teenagers are breaking their parents rule: If you borrow my car,then you have to fill up the tank with gas.Don't turn over any more cards than are absolutely necessary.

P not-P Q not-Q

borrowed

car

did not borrow

car

filled up tank

with gas

did not fill up

tank with gas

76% answer P & not-Q


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How the mind sees this problem...

The mind translates social contracts into representations of benefits and

requirements, and it inserts concepts such as entitled to andobligated to, whether they are specified or not.


If you take the benefit, then you are obligated to satisfy the

requirement.

If P then Q

borrowed

car

did not

borrow car

filled up tank

with gas

did not fill

up tank with

gas

Accepted

the benefit

Did not

accept the

benefit

Satisfied the

requirement

Did not

satisfy the

requirement

P not-P Q not-Q


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Programs specialized for social exchange

What design features do they have?

Cheater detection

Familiarity not relevant

Adaptive logic, not formal logic

Benefits and costs relevant

Cheating versus innocent mistakes

Perspective-dependent definition of cheating

Cross-cultural development

Neurally dissociable from other forms of

reasoning


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Are programs specialized for reasoning

about social exchange the ONLY

cognitive instincts in the human mindfor regulating cooperation?

2-person cooperation (social exchange,trade, reciprocation)

N-person cooperation (collective

action)


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How the mind sees this problem...

The mind translates social contracts into representations of benefits and

requirements, and it inserts concepts such as entitled to andobligated to, whether they are specified or not.


If you take the benefit, then you are obligated to satisfy the

requirement.

If P then Q

borrowed

car

did not

borrow car

filled up tank

with gas

did not fill

up tank with

gas

Accepted

the benefit

Did not

accept the

benefit

Satisfied the

requirement

Did not

satisfy the

requirement

P not-P Q not-Q


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Cheating logical violation

1. Standard: Ifyou give me your watch, I will give you $100

If P then Q

2. Switched: If I give you $100, then give me your watch

2. Switched format Q not-P NO

In mentalese...

I accepted the

benefit from

you

I did not

satisfy your

requirement

1. Standard format P not-Q YES

You gave me

your watch

I did not give

you $100

Logically

correct?

I cheated you if:

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