PSYA02H3 Chapter Notes - Chapter 11: Orgasm, Bisexuality, Heterosexuality

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21 Mar 2015

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PSYA02 Chapter 11 Notes
11.1 – Hunger and Eating
-Motivation: Concerns the physiological and psychological processes underlying the initiation of
behaviours that direct organisms toward specific goals
oInclude the thoughts, feelings, sensations, and bodily processes that lead to goal-directed
oWhen the body’s water levels fall below normal, cells release chemical compounds that maintain
the structure and fluid levels of cells
-Drive: A biological trigger that tells us we may be deprived of something and causes us to seek out what
is needed, such as food or water
oWhen satisfied, reward centers in our brains become activated, reinforcing our behaviour by
making it more likely to respond
oIncreased thirst drink water increased water volume decreased thirst don’t drink cellular
messages of lowered water concentration sent to the brain
-Homeostasis: The body’s physical biological processes that allow it to maintain consistent internal
states in response to the outer environment
oJanice eating candy: The experience of anxiety [for an exam] uses a lot of energy, as does the
effort required to control your emotions; if she didn’t meet the new energy demands, her energy
level would quickly decrease
-Allostasis: Motivation is not only influenced by current needs, but also by the anticipation of future
- The need to consume enough nutrients so that you have enough energy to function involves
physiological responses as well as more complex cognitive and emotional factors
- Researchers have found that electrically stimulating the lateral hypothalamus causes rats to begin to eat;
thus, this structure may serve as an “on” switch
oStimulating the ventromedial region of the hypothalamus causes rats to stop eating
Damaging the “off” switch leads to obesity because animals don’t stop eating
oBrain influences your body and your body influences your brain
-Glucose: A sugar that serves as a primary energy source for the brain and the rest of the body
oSpecialized neurons (glucostats) detect glucose levels in the fluid outside of the cell
Too low = gluostats signal the hypothalamus that energy supplies are low, increasing
After food reaches the stomach and intestines, sugars are absorbed into the bloodstream
and transported through the body
oInsulin (hormone secreted by the pancreas) helps store the circulating glucose
Rise in response to consumption of a meal in order to decrease hunger
-Satiation: The point in a meal when we are no longer motivated to eat
oCaused by cholecystokinin (CCK)
When neurons release CCK because the intestines expand, the ventromedial
hypothalamus decreases the appetite
oInfluences how rewarding we find a food
oParticipants in a research rated chocolate as being tasty, leading to activity in the orbitofrontal
cortex (the part of the frontal lobes just above your eyes), a brain area that judges the reward
value of food
Insula receives information about taste, and the basal ganglia, which respond to physical
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Activity in the reward centers moved to other areas of the frontal lobe, showing that a
number of different brain areas are involved when we are / are not motivated to eat
Quick Quiz 11.1a
1) The lateral region of the hypothalamus is associated with the onset of eating while the ventromedial
region is associated with the offset
2) Glucose is a sugar that serves as a vital energy source for the human body; its levels are monitored by
the nervous system
3) Why do psychologists believe the lateral hypothalamus generates hunger signals that contribute to
people’s motivation to eat? When the lateral hypothalamus is stimulated, laboratory animals eat more
- We developed bodies that were hard-wired to like some foods more than others
- Scientists suggest that we crave fats because we have specialized receptors on the tongue that are
sensitive to the fat content of food
oWhen the receptors are stimulated, the cingulate cortex a region of the brain involved in
emotional processing is activated, while the orbitofrontal cortex is involved in linking food
taste and texture with reward
oParticipants of a study rated fatty substances favourably, and the brain scans showed activity in
regions of the brain associated with pleasure sensations when they tasted fat
- High-energy food can be a more powerful reinforcer than highly addictive drugs
oSugar fix = addiction to candy and chocolate bars compared to an addiction to drugs
oOrdinary sucrose plain white granulated sugar can stimulate release of the neurotransmitter
dopamine in the nucleus accumbens, a brain region associated with the reinforcing effects of
substances such as amphetamines and cocaine
- Stress modulates ghrelin, a hormone secreted in the stomach that stimulates stomach contractions and
oFeeling stressed = viewing a situation as threatening, therefore reacting by stocking up on energy
reserves so that you can deal with it
- Bottomless bowl of soup: A tube continued to fill the soup bowl from the bottom so that it could not be
detected by the volunteers, so they were asked to eat soup until they had enough
oThese individuals stopped eating after consuming, on average, and over 70% more than those
participants who knowingly refilled their bowls
oIndividuals eating from bottomless bowls did not feel any ore satiated, nor did they believe they
had eaten any more than the individuals in the control group
We can’t put breaks on ourselves when we don’t keep a track of how much we eat
-Unit bias: The tendency to assume that the unit of sale or portioning is an appropriate amount to
consume (ex. A banana is individual and is a healthy portion, therefore an ideal unit)
- Participants were given fresh or stale (14 day old) popcorn in either a small or large container; the larger
the container, the more popcorn, even if it was really stale
oLarger bowl implies that it’s normal to eat more
-Social facilitation: Eating more, the longer a person sits socializing, the more likely he or she is to
continue nibbling
-Impression management: Eating less, minimal eating norm suggests that an aspect of good manners is to
eat small amounts to avoid seeming rude
-Modeling: Eating whatever they eat, a person will watch how much their company is eating and behave
in the same way
Quick Quiz 11.1b
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1. The minimal eating social norm is the observation that people to view eating reasonably sized portions
as the polite thing to do
2. Sometimes being around others can lead you to eat more or less than you normally would
3. In Europe, the typical container of fruit and yogurt is roughly 177mL. In North America, the same food
item is usually packaged at 237mL containers. The unit bias suggests that a German person visiting
Canada would be likely to eat the entire container, even though it contains 25% more than the typical
German serving
4. How do evolutionary psychologists explain our desire to eat particular foods? The foods we now find
pleasurable are often high-energy foods that would have enhanced our chances for survival in the past
-Obesity: A disorder of positive energy balance, in which energy intake exceeds energy expenditure
oApprox. 20% of Canadians had a height and weight ratio that would classify them as obese; over
60% of Canadian adults could be classified as overweight
Lowest in Quebec, highest in Atlantic Canada, territories, and Saskatchewan
- Obesity tends to affect the poor more than the rich because unhealthy, energy-dense foods are less
expensive than healthy ones
oMore fast-food outlets in low-income neighbourhoods
oLeads to other serious health problems
-Anorexia nervosa: An eating disorder that involves self-starvation, intense fear of weight gain and
dissatisfaction with one’s body, and a denial of the serious consequences of severely low weight
oAppear indifferent to the negative effects the food deprivation is having on their health
-Bulimia nervosa: An eating disorder characterized by periods of food deprivation, binge-eating, and
oShort bursts of intense calorie consumption, followed by purging, fasting, or intense exercise
oMarked by a tendency to be impulsive; more likely to enter treatment programs because they
find the binge-purge cycle disturbing
- Stress is a huge factor in eating disorders; tend to make people feel as though they have no control over
their lives
oJoined with guilt, depression, anxiety, perfectionism, low self-esteem, and/or anger
Combination of these things increase the chances of eating disorders
- Peer influence is another factor because adolescents, particularly females, learn attitudes and behaviours
from their friends
- Media is a huge factor because it promotes “thinspiration” through photographs and messages
- Families are a factor because if they are more controlling, the female would not have autonomy (control
over their own lives), leading to an increased risk of an eating disorder
- People use eating disorders as a coping mechanism to deal with their difficult-to-control lives; by
making their bodies a primary focus, they would feel some security and in control of some aspect of
their life
oIndividuals with bulimia reported less anxiety, tension, and guilt issues although feelings of
depression stayed the same
oWhen the feelings of control are reduced, individuals with eating disorders become more
pessimistic and report feeling fatter than before
-Reproductive suppression hypothesis states that females who believe they have low levels of social
support from romantic partners and family members are more likely to engage in dieting behaviours;
influences ovulation and can lead to a loss of menstrual periods (decreasing chances of pregnancy)
- Adolescent males may starve themselves during periods of high exercise to lose weight and achieve
muscle mass
o“Reverse anorexia” = just as obsessive / perfectionistic about their bodies as people with
Quick Quiz 11.1c
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