Section 2.1 in the IB Psychology textbook

1. Biological Level of
Analysis
Physiology and Behavior

2. Principles
• There are physiological origins of many
behaviors
• Human beings should be studied as
biological systems
• Consider how the environment and
cognition may interact with biological
systems and affect physiology
– Biology can affect cognition and vice versa

3. Physiology
• Some physiological factors which can affect
behavior:
– Brain processes
– Neurotransmitters
– Hormones
– Genes
• Physiology responds to environmental
stimuli

4. Physiology
• Nature versus nurture debate:
– Is human nature the result of environmental
factors or biological factors?
• Interactionist approach:
– Mix of the two arguments
– Holistic picture of human behavior
– This is the goal of I.B. Psychology

5. Principles
• Behavior can be innate because it is
genetically based
– Thus, evolution plays a key factor in behavior
• Animal research can provide insight into
human behavior
• There are biological correlates of behavior
– Should be possible to find links between
biological factors and specific behaviors

6. Principles
• Reductionist approach is commonly used
– Micro-level of research
– Breaks down complex human behavior into its
smallest parts
– Could be overly simplistic, but it is detailed

7. Neurotransmission
• Neurotransmission underlies behavior:
NEUROTRANSMITTER EFFECT ON BEHAVIOR
Acetylcholine •Muscle contraction
•Affects memory in hippocampus
Dopamine •Voluntary movement
•Learning
•Pleasure
Noradrenaline •Arousal
•Alertness
•Stimulation of sympathetic nervous
system
Serotonin •Sleep
•Arousal levels
•Emotion

8. Kasamatsu and Hirai (1999)
• Aim: See how sensory deprivation affects the
brain
• Method: Studied Buddhist monks on a 3-day
pilgrimage
– No food or water, no speaking, cold weather
– Started hallucinating after 48 hours
• Blood samples before and after pilgrimage:
– Serotonin levels heightened
– Serotonin activated hypothalamus and frontal
cortex = hallucinations
– Sensory deprivation = release more serotonin

9. Martinez and Kesner (1991)
• Aim: Determine the role of the
neurotransmitter acetylcholine on
memory
• Method: Rats in a maze
– One group of rats given scopolamine to block
acetylcholine from being transmitted
– Second group given physostigmine which
keeps cholinesterase from monitoring levels
of acetylcholine
– Third group as control

10. Martinez and Kesner (1991)
• Results:
– (First group) Inhibited acetylcholine = rats were
slow and made errors
– (Second group) Inhibited physostigmine = rats
were fastest
– (Third group) Control = average speed (between
the first and second group)
• Conclusion: Acetylcholine is important in
creating memory
• Experiment was well designed, but it is
unclear how much this relates to human
physiology

11. Drugs
• Drugs can simulate a certain
neurotransmitter
– When there is not enough of the
neurotransmitter
– When the site needs to be blocked

12. Brain & Behavior
• Brain is the command center of activity
• Case studies of brain damage help
understand how the brain affects behavior
– Often longitudinal studies (carried out over a
long period of time) to see short-term and
long-term affects of damage

13. Phineas Gage
• Famous case study of brain damage and
behavior
– Phineas Gage was studied by Dr. John Harlow
• Metal pole through skull (but still managed to
survive???)
• Ruined the balance between his intellect and
his emotional control
– Impatient, indulgent, profane, agitated, vulgar
• Shows that the brain affects personality
and social behaviors

14. Localization of Brain
Function
• Paul Broca (1861) found people with
damage to the left frontal lobe couldn’t
understand or make grammatically complex
sentences
• Broca’s aphasia: Problems producing
speech, but still able to understand it
– Famous patient called Tan because that’s the
only word he could say

15. Localization of Brain
Function
• Carl Wernicke (1874) found area of brain
crucial for language comprehension
– Described as left posterior superior temporal
gyrus
• Wernicke’s aphasia: Patients could
produce speech, but could not understand
it

16. Localization of Brain
Function
• Language processing is localized
– Meaning it is possible to trace the origin of the
behavior to a specific part of the brain
• Desire to map out brains functions
• Localization doesn’t explain all human
behavior, but it’s a start!

17. Robert Heath (1950s)
• Found that electrically stimulating parts of
the brain caused pleasure in patients with
depression
• Patients could press the button themselves
to experience the pleasure
• Patient B-19 pressed it 1500 times in 3 hours
– Had to be disconnected despite protests

18. Dopamine & Serotonin
• Dopamine produces desire
• Serotonin promotes satiety and inhibition
• All drugs increase production of dopamine
and reduce production of serotonin
• Both D&P play central roles in feelings
produced by drugs like cocaine and nicotine
• James Olds: Rats would walk over
electrified grids to get to a lever that would
stimulate the pleasure centers in their brains

19. Technology in Brain
Research
• Allows researchers to see where specific
brain processes take place (localization)
• Invasive techniques: removing/scarring
brain tissue in order to study behavioral
changes to compare the effect
• Raise ethical concerns (DUH!)
– Can’t undo it
– Can’t foresee the potential harm
– Hurting poor little defenseless animals!!!!!!

20. EEG
(Electoencephalogram)
• Often thought of as recording “brain
waves”
• Registers patterns of voltage change in the
brain
• Provides limited information
– Cannot reveal what is happening in deeper
brain regions
– Can’t show the actual functioning of the brain

21. PET (Positron Emission
Topography)
• Monitors glucose metabolism in the brain
• Used to diagnose abnormalities
– i.e. tumors, Alzheimer’s progression,
comparisons in sexes or disorders
• Can record ongoing activity in the brain
such as thinking

22. fMRI (Functional Magnetic
Resonance Imaging)
• 3D pictures of the brain structures using
magnetic fields and radio waves
• Shows brain activity and indicates which
areas are active when engaged in a
behavior
• Higher resolution than PET scans
• Easier to carry out than PET scans
• Used super frequently today

23. Brain Plasticity
• Brain can change as a response to
environmental input
– Demonstrated by Hubel and Wiesel (1965)
• Brain plasticity: brain’s ability to
rearrange connections between neurons
– Changes that occur in the structure of the
brain as a result of learning or experience
• More stimulation and learning
opportunities = denser neural connections

24. Dendritic Branching
• When we learn something new the neurons
connect to create a new trace in the brain
• This is called Dendritic branching
– Dendrites of the neurons grow in numbers and
connect with other neurons

25. Rosenzweig & Bennett (1972)
• Enriched environments vs. deprived
environments & their effects on rats
– Enriched = toys
– Deprived = no toys
• Enriched environment created thicker
cortex and heavier frontal lobe in rats
• Rat + toys + other rat friends = biggest
growth in cortical thickness

26. Richard Davidson (2004)
• Meditation of Buddhist monks and 10
volunteers
• Monks and 2 volunteers had an increase in
gamma waves during meditation
– Gamma waves = higher reasoning faculties
• After meditating for 10,000+ hours, the monks
did not go back to normal gamma wave
production afterwards
• Therefore meditation can have long-term
effects and the brain adapts to stimulation

27. Mirror Neurons
• People can learn by observing others and
imitating their actions
• Mirror neurons fire when someone
performs an action or when someone else
performs the same action
– May play a vital role in learning from and
empathizing with someone
• It “mirrors” the behavior of another

28. Gallese et al. (1996)
• Could hear crackle of electrical signal
caused by activated neurons
• Monkey’s neurons crackled when it
reached for a peanut to eat
• Heard crackling noise again when
researcher reached for a peanut to eat
• Monkey’s brain acted as though the
monkey had carried out the behavior just
because it saw someone else carry out the
behavior

29. Marco Iacoboni (2004)
• Tested mirror neurons in humans
• Supported Gallese’s findings
• Observing a happy face activates pleasure
centers in the brain
• Could explain how we “feel” the hit a football
player feels when they get tackled
• Mirror Ns may have evolved to make us
capable of understanding/interacting with
others

30. Endocrine System
• Hormones affect behavior too
• Produced by the glands that make up the
endocrine system

31. Hormones & their Functions
Hormone Glands Function
Adrenaline Adrenals •Fight or flight response
•Arousal
Melatonin Pineal •Regulation of sleep
Testosterone and
Oestrogen
Gonads •Development
•Emotion
Oxytocin Pituitary
Hypothalamus
•Mother-child
attachment

32. Oxytocin
• Induces labour contractions and lactation
• Released with touches and hugs
– Bond between mother & child, and lovers
• Called “the love hormone”
• Affects fear regulation in brain; increases
trust and generosity

33. Melatonin
• Researchers study melatonin in hopes of
helping insomnia and jet lag
• Production of melatonin is stimulated by
darkness and inhibited by light
• Levels peak in the middle of the night
• Earlier onset of darkness in winter makes
us feel tired earlier
• Melatonin pills may help with falling asleep

34. Seasonal Affective
Disorder (SAD)
• Rosenthal (1987)
• Subcategory of depression with sleepiness
and lethargy
• Winter darkness disrupts circadian
rhythm in people (biological clock) which
leads to depression
• Exposure to sunlight and bright light may
improve symptoms