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Chapter 1

PSY321H1 Chapter Notes - Chapter 1: Encephalization Quotient, Imitative Learning, Encephalization

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Nick Rule

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- in many ways, humans seem ill adapted to survive
- we rely on culture more than any other species, allowing us to succeed in diverse
environments, and affecting our thoughts and behaviours
A Psychology for a Cultural Species
- people from different cultures also differ in their psychology
- major theme: psychological processes are shaped by experiences
- psychological processes are constrained by the neurological structure of the brain which is
virtually identical around the world
- to what extent should ways of thinking look similar around the world because people
share a universal brain?
- to what extent should they look different because people have divergent experiences?
- major theme: universal and culturally variable psychologies
What Is Culture?
- no single consensual answer that applies to all fields
- in the book, it is used to mean two different things
- to indicate a particular kind of information that is acquired from other members of one’s
species through social learning that is capable of affecting an individual’s behaviour
- any idea, belief, technology, habit, or practice that is acquired through learning
from others
- to indicate a particular group of individuals who are existing within some kind of shared
- e.g. same cultural institutions, engage in similar cultural practices
- challenge 1: cultural boundaries aren’t distinct, weakens researchers’ abilities to find
differences between cultures
- challenge 2: cultures aren’t static entities but are dynamic and change over time
- challenge 3: there is much variability among individuals within the same culture
- cultural membership doesn’t determine individual responses
Is Culture Unique to Humans?
- controversial, in part, because of the lack of consensus regarding a definition for culture
- definition provided by Heine is much broader
- “Imo” a macaque on a small island off of Japan
- after being given some pieces of potato, Imo washed the sand off before eating them
- within 3 months, Imo’s mother and some playmates also started washing their potatoes
- after 3 years, 40% of the macaques in Imo’s troupe were washing their potatoes
- potato washing became part of the cultural repertoire of a subgroup of macaques
- chimpanzees have been shown to use tools to extract termites
- these learned behaviours are culturally transmitted from one generation to another
- a herd of elephants that was mostly systematically eliminated came to respond extremely
aggressively to humans

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- parallels aggressive human cultures that have experienced generations of warfare
Cultural Learning
- humans stand out in the extent of their cultural learning skills
- we frequently learn new information from others, often with only a single exposure
- humans choose whom they imitate
- detecting “prestige”, seeking others who have skills and are respected by others
- in learning a skill from others, it isn’t always clear what particular behaviours are responsible to
achieve success
- individuals fare best by having a general imitating mechanism (observe prestigious
individuals and try to imitate them, regardless of what they’re doing)
- humans’ sophisticated cultural learning skills rests on the ability to consider the perspective of
others and the ability to communicate with language
Theory of Mind
- people understand that others have minds that are different from their own, thus have different
perspectives and intentions
- e.g. a child will point to a toy he wants, indicating he understands that his mother isn’t
aware of where the toy is
- not evident in most other species
- imitative learning, the learner internalizes something of the model’s goals and behavioural
- emulative learning, the learning is focused on the environmental events that are involved
- doesn’t require imitating a model’s behavioural strategies
- only focuses on what the model appears to be doing, rather than what the model intends
to accomplish
- Nagell, Olguin, & Tomasello (1993) chimps and 2-year-old children learned a novel task
- rake-like tool and desired object that was kept out of reach
- the model used the rake to get access to the object
- most effective way, rake turned with the teeth pointing up
- rake used in ineffective way, with the teeth pointing down
- children showed evidence of true imitative learning, they tried to do precisely what the
model had done
- chimps showed evidence for emulative learning, regardless of the model, they used the
rake in the most effective way
- emulative learning can be very effective but doesn’t allow cultural information to accumulate
Language Facilitates Cultural Learning
- allows ideas to be communicated without having to be visually demonstrated
- makes it possible for people to convey their beliefs, intentions, and complex thoughts
- facilitates coordination of behaviour among individuals living in groups
- some animal species have some features of language
- humans from all cultures have complex grammar and syntax

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Cumulative Cultural Evolution
- ratchet effect, after an initial idea is learned from others, it can then be modified and improved
upon by other individuals
- cultural information thus grows in complexity, and often in utility, over time
- need creative invention and reliable and faithful social transmission, which requires accurate
imitative learning and sophisticated communication
- the tools we use are the most recent product of years, if not millennia, of accumulated cultural
- these innovations grow at exponential rates
- cultural ideas (e.g. democracy) also represents the accumulation of ideas
- argument psychological mechanisms can undergo cumulative cultural evolution as well
- e.g. mathematical reasoning
Why Are Humans Adept at Cultural Learning?
You and Your Big Brain
- encephalization quotient, the ratio of the brain weight of an animal to that predicted for a
comparable animal of the same body size
- ~4.6 for humans
- our brain consumes ~16% of our basal metabolism, compared to 3% in the average mammal
- non-human primates have encephalization quotients of 1.9-2.5, selection for big brain...
- many primates eat a lot of fruit, selection for cognitive abilities that would help them keep
a mental map of short-lived and patchily distributed fruit
- many food sources require a fair bit of ingenuity to access, selection for cognitive skills
needed to allow primates to extract these foods
- complexity of primates’ social worlds, social brain hypothesis
- neocortex ratio, volume of the neocortex to the volume of the rest of the brain
- used as a proxy measure of intelligence
- ratio tested against three theories
- little correlation to percentage of fruit in diet and extractive forging strategies
- strong correlation between ratio and average group size of different species
The Magic Number of 150
- if humans were plotted on figures based on their neocortex ratio and average group size, the
average size of human ancestral populations would be ~150
- Dunbar (1993) surveyed present-day subsistence societies, found the average size of clans
was 148.4
- provided evidence that many modern groups function best with ~150 members
- e.g. Hutterites, a fundamentalist Christian sect divide into new communities whenever
one reaches 150 people
- reasoning is that peer pressure is a powerful means of social control until that size
- e.g. Gore-Tex fabrics build a new plant whenever employee numbers reach 150
- to summarize, humans evolved to participate in complex social environments
- the ability to engage in cultural learning was a selective force that has shaped human evolution
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