Transcript Slide 1 - UBC Psychology`s Research Labs

Psychology 305A:
Personality Psychology
October 1
Lecture 7
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ASTU 400U
Disordered Eating – Biology and Behaviour
How Does it Work?
• A student-led seminar (12-15 participants)
• We explore and teach each other the course material as a group
What Are We Learning About?
• The characteristics, underlying mechanisms, and treatment of
disordered eating!
• Topics ranging from obesity and food addiction, to bulimia nervosa
and anorexia nervosa
• Special focus on clinical and biological approaches
Interested?
• Email Jacob Sussman (course coordinator) [email protected]
for more information about the course and for answers to any questions
you might have
• Check out the SDS website:
http://studentdirectedseminars.ubc.ca/2013-2014-seminars/
The Biological Perspective
1. What are the basic principles of evolutionary theory?
2. How have the basic principles of evolutionary theory
been adapted to the study of personality?
3. What hypotheses has the evolutionary approach
generated regarding (a) altruism and (b) sex
differences in the desire for sexual variety?
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By the end of today’s class, you should be able to:
1. describe natural selection, sexual selection, intrasexual
selection, and intersexual selection.
2. generate examples of distinct forms of selection.
3. define the term inclusive fitness.
4. review research supporting evolutionary hypotheses
related to altruism.
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5. define the terms reproductive capacity and minimal
parental investment.
6. review research supporting evolutionary hypotheses
related to sex differences in the desire for sexual
variety.
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What are the basic principles of evolutionary theory?
• Darwin proposed two processes through which evolution
occurs:
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1. Natural selection
 A process through which organisms develop
characteristics that enhance their ability to survive.
 Organisms who possess characteristics that enhance
their ability to survive are more likely to live to
reproductive age and pass these characteristics on to
the next generation.
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 Offspring who inherit these characteristics are more
likely to survive to reproductive age and pass the
characteristics on to yet the next generation.
 Across successive generations, the “survivalenhancing” characteristics increase in frequency until
they characterize most members of the species.
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 Example: The preference for sweet, fatty, and salty
foods among humans.
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2. Sexual selection
 A process through which organisms develop
characteristics that enhance their ability to reproduce.
 Darwin proposed two mechanisms through which
sexual selection occurs:
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(a) Intrasexual selection
 Occurs when same sex organisms compete for the
sexual interest of the opposite sex.
 Organisms who possess characteristics that enable
them to “win” the sexual interest of the opposite sex are
more likely to mate and pass these characteristics on
to the next generation.
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 Offspring who inherit these characteristics are more
likely to mate and pass the characteristics on to yet the
next generation.
 Across successive generations, the “winning”
characteristics increase in frequency until they
characterize most members of that sex of the species.
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 Example: The aerial hover display of the male
bronzed cowbird.
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(b) Intersexual selection
 Occurs when organisms of one sex prefer to mate with
organisms of the opposite sex who possess specific,
desirable characteristics.
 Organisms who possess characteristics that are
desirable to the opposite sex are more likely to mate and
pass these characteristics on to the next generation.
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 Offspring who inherit these characteristics are more
likely to mate and pass the characteristics on to yet the
next generation.
 Across successive generations, the desirable
characteristics increase in frequency until they
characterize most members of that sex of the species.
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 Example: The brilliant plumage of the male peacock.
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How have the basic principles of evolutionary theory
been adapted to the study of personality?
• Evolutionary psychologists believe that our basic
psychological processes are the product of natural
selection and sexual selection.
• Our psychological processes are seen as adaptations to
the survival and reproductive challenges faced by our
ancestors.
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What hypotheses has the evolutionary approach
generated regarding altruism?
• Altruism: A desire to help others, often at the risk of
one’s own well-being.
• Theory of inclusive fitness: Organisms are motivated to
enhance the survival and reproductive potential of
those who are genetically similar to them.
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• Following from the theory of inclusive fitness,
evolutionary psychologists generated two hypotheses:
 Hypothesis A: Helping behaviour increases as the
degree of genetic overlap increases between the helper
and the recipient.
 Hypothesis B: Helping behaviour increases as the
reproductive potential of one’s kin member (i.e., relative)
increases.
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• Burnstein et al. (1994; also see Laham et al., 2005):
 Recruited American and Japanese participants.
 Had participants imagine that people were asleep in
a rapidly burning building.
 Told participants they could only rescue one person.
 Asked participants to indicate who they would be
most willing to save.
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 Results consistent with
Hypothesis A.


Tendency
to Help


.50
Highly Related
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.25
.125
Degree of
Genetic Overlap
.00
Not Related
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 Results consistent with
Hypothesis B.


Tendency
to Help



1
10
18
45
75
Age of Kin (Years)
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 Results consistent with
Hypothesis B.

Tendency
to Help


Healthy


Sick

.50
Highly Related
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.25
Degree of
Genetic Overlap
.125
Not Highly Related
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What hypotheses has the evolutionary approach generated
regarding sex differences in the desire for sexual variety?
• Females and males differ in their reproductive capacity
and the minimal parental investment that is required to
produce an offspring:
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• Reproductive capacity: Males > Females
 Females: Can bear 8 – 12 offspring across the lifespan.
 Males: Can bear an almost unlimited number of
offspring across the lifespan (maximum recorded to
date: 900).
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• Minimal parental investment: Females > Males
 Females: Carry and nourish fetus for 9 months; nurse
child after birth; during lactation, ovulation is suppressed.
 Males: Engage in copulation.
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• Given sex differences in reproductive capacity and
minimal parental investment, evolutionary psychologists
maintain that males and females have developed
different strategies to maximize their reproductive
potential:
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• Males: Employ strategies that enable them to copulate
with as many females as possible.
• Females: Employ strategies that restrict copulation to
males who are able to provide care and resources for
the offspring.
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• Following from these strategies, evolutionary
psychologists generated two hypotheses:
 Hypothesis A: Males are less discriminating in their
selection of sexual partners than females.
 Hypothesis B: Males are inclined to seek more sexual
partners than females.
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• Studies that have tested these hypotheses include:
 Clark and Hatfield (1984)
 Had confederates approach students of the opposite sex
on campus.
 After saying “Hi, I’ve been noticing you around campus
lately and I find you very attractive,” the confederates
asked the students 1 of 3 questions:
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Percent Who Agreed
Male
Female
“Would you go out on a date
with me tonight?”
50
55
“Would you go back to my
apartment with me tonight?”
69
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“Would you have sex with me
tonight?”
75
0
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 Buss and Schmitt (1993)
 Asked unmarried participants how many sex partners
they would like to have through to the end of their lives.
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 Results consistent with
Hypothesis B.
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Males
15

Desired
Number
10
of
Partners
5

0 
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
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

Females



1
2
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
3


4
5
Time (Years)



10
20
Life
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 Schmitt et al. (2003): Found similar sex differences
across 52 nations (e.g., Argentina, Austria, Canada,
Chile, Croatia, Greece, Israel, Italy, Japan, Lebanon,
Slovakia, Zimbabwe, US).
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By the end of today’s class, you should be able to:
1. describe natural selection, sexual selection, intrasexual
selection, and intersexual selection.
2. generate examples of distinct forms of selection.
3. define the term inclusive fitness.
4. review research supporting evolutionary hypotheses
related to altruism.
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5. define the terms reproductive capacity and minimal
parental investment.
6. review research supporting evolutionary hypotheses
related to sex differences in the desire for sexual
variety.
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