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YALE PSYC 110 NOTES
INTRODUCTION TO
PSYCHOLOGY 2025
COMPLETE UPDATED
STUDY MATERIAL
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PSYC 110 – The Brain
• Phineas Gage, Summer 1848
o Metal bar through skull (vertically) in railroad construction
accident o “The most efficient, capable man, shrewd
businessman” -> “fitful, irreverence, indulging at time in
the grossest profanity, manifesting but little deference for
his fellows”
• Self-control, ambition, drive, behavior toward friends and family
are extensions of workings of the brain, and can be lost after brain
injury
• Most people believe in dualism o Descartes (1596-1650) o
Animals as reflex machines/robots
o We have material bodies, but our minds are immaterial
and non-physical (2 components: physical brain and
nonphysical “mind”)
o Argument 1: The creativity and spontaneity of human
action o Argument 2: “I think, therefore I am.”
People who are dreaming believe untrue things o Dualism seems
right, right?
Language: “my arm” “my leg”
Personality identity: same person after radical bodily changes;
many people can occupy a single body (multiple personality disorder)
Demonic possession: something can enter your body, and take it
over?
is wrong! Mind = Brain.
o Problems with dualism – no dualist has never fully,
successfully explained how the immaterial soul can
interact with the physical body
o How can the supposed immaterial mind be influenced by
alcohol, a physical substance?
o We now have a better understanding of what physical
things can do (dualists once posited that to-be-computers
could never play chess, but now we know they can)
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o
How does the brain work?
o Starting point: the neuron
o Dendrites are sensors on neurons that get signals from
other neurons – either excitatory or inhibitory; when a
certain level is reached, a neuron fires: neural impulses
sent down the axon to axon terminals, which send
chemicals to other dendrites o Neurons
About 86,000,000,000
Sensory neurons (go from the world to the inside of
you), motor neurons
(muscular movement), interneurons (connect neurons to other neurons)
Neurons fire all-or-nothing; intensity can be
expressed through number of neurons firing and/or
frequency of firing
Communication over synapses (small empty spaces
between the axon of one neuron and the dendrite
of another); axons release neurotransmitters
• Excitatory: neurons become more likely to fire
• Inhibitory: neurons become less likely to fire
• Curare is an antagonist on motor neurons (results in an increased
resistance to pain)
• Alcohol is an antagonist that inhibits parts of the brain that
regulate certain behaviors
• Amphetamines (speed) are agonists that increase epinephrine
levels
• Prozac is an agonist that increases serotonin levels (thus
decreasing depression)
• Is the brain wired up like a personal computer (How are neurons
wired up to do what they do)?
o No, because the brain is highly resistant to damage, extremely fast, and unlike
most human-designed computers, the brain works through massively parallel
processing
• What do different parts of the brain do?
o You don’t need your brain for everything, including…
Sucking in newborns
Limb flexion in withdrawal from pain
Erection of the penis
Vomiting
o Some subcortical structures
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Medulla: autonomic functions: heartbeat,
breathing, blood pressure, swallowing, vomiting,
etc
Cerebellum: complicated skilled motor movements,
mental and sensory tasks; automation of many
tasks
Hypothalamus: hunger, thirst, sleep, body
temperature – regulatory component that
performs homeostatic functions
o The cerebral cortex – the outer layer
Higher thinking – love, passion, violence, etc –
happens here
Sensory map in the somatosensory cortex, motor
map in the primary motor cortex
• Topographic (corresponds to body location) and ranks importance
Some very bad things that could happen to you and your brain o
Apraxia
o Agnosia – inability to recognize things
Visual agnosia
Prosopagnosia – inability to
recognize faces o Sensory neglect
• How many minds do you have?
o Brain has two hemispheres, left and right, which do
different things
o Sensory Information sent to opposite hemisphere o
Two hemispheres are connected by corpus
callosum
spread of electric storms across the brain), brain halves can act
independently
• Hard problem of the consciousness, subjectivity, a qualia; this lecture presented a
mechanistic conception of mental life, but what about humanist values? Free will and
responsibility, intrinsic value, spiritual value?
PSYC 110 - Freud
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