Mod. 37-38

37.1 Define motivation as psychologists use the term
and identify the perspective useful for studying
motivated behavior.
• Motivation: need/desire that energizes and directs
4 perspectives:
• Instinct Theory (Evolutionary Theory): genetically
predisposed behavior
• Drive Reduction Theory: see homeostasis
• Arousal Theory: seeking stimulation (Yerkes-Dodson)
• Maslow’s Hierarchy of Needs: What of the levels/stages
are the most important?
Instincts and Evolutionary Perspective
• Due to Darwin came the idea to classify many behaviors
as instincts
• Instinct: unlearned but complex behavior that is ingrained
in a species (reflexes)
• Evolutionary psychology: genes do predispose our
Drives and Incentives
• Drive Reduction theory: a physiological need creates
tension/arousal (drive) that organism wants to satisfy
• Seek homeostasis: balanced internal state
• Also seek incentives: (extrinsic/intrinsic) positive or negative
environmental stimuli that motivates behavior
• Combined with needs=feel strong drive
Optimum Arousal
• Sometimes we seek more arousal
• Yerkes-Dodson: performance increases with arousal up
to a point, too much arousal becomes a detriment
Hierarchy of Motives (Maslow)
• Some needs are more important at some points
38.1 Describe the physiological factors
that produces hunger
• Body Chemistry and the Brain
• Major source of energy is glucose: sugar that is used by body for
energy. Low=hungry
• Stomach, intestine, and liver work with brain
• Hypothalamus—influences eating
• Neural arc secretes appetite stimulating hormone, another arc secretes
the opposite
• Lateral hypothalamus: causes you to eat
• Ventromedial hypothalamus: causes you
to feel satisfied
• Registers chemicals/hormones: (next slide)
• Ghrelin: hunger arousing
Insulin: controls glucose,
secreted by the pancreas
Leptin: causes
metabolism to increase
and hunger to decrease,
secreted by actual fat cells
Orexin: increases hunger,
secreted by hypothalamus
PYY: tells the brain you
are no longer hungry,
produced by digestive tract
Weight Thermostat
• We hover around a set point: a “weight” for an individual
that controls metabolism and weight loss
• Basal metabolic rate: resting rate of energy being
38.2 What cultural and situational factors
influence hunger
• Taste Preferences: Biology and Culture
• Carbs/sweets boost serotonin…calming
• Sweet/salty: genetic and universal
• Conditioning can change taste
• Culture teaches “acceptable” foods
• Biological/environment influence taste
Situational Influences on Eating
• Ecology of eating
• Eat more with others
• Unit bias—difference between Europeans/Americans
• Food Variety
• Eat more when offered more
Environmental Factors of Obesity
• Sleep loss: vulnerable to weight gain
• Lowers leptin to report fat levels to the brain and increases ghrelin