Biological Approach concepts

Experiment

• Procedure is standardized (replicable)

• Can establish cause and effect relationships

• Data can be statistically analyzed to determine the role of chance in the results

• A control condition is used

• Demand characteristics can occur

True experiment

• Participants are randomly allocated to conditions (decreases likelihood that individual characteristics impact results)

• Researcher manipulated IV

Laboratory experiment

• High controlled to prevent extraneous variables

• Low ecological validity

Field experiment

• Done in a natural setting

• Cannot prevent extraneous variables and are difficult to replicate

Quasi experiment

• Participants are grouped by a trait or behavior

• Doesn’t show direct causation but implies a causal relationship (less control over pre-existing variables)

Correlational study (twin studies or family studies)

• Tests the correlation between variables (not cause and effect)

• Variables are only observed (not manipulated)

• Limited control (high likelihood of extraneous variables)

• High external validity (conclusions can be generalized to other populations)

Case study

• And in-depth study of an individual (or group of people) with a particular condition

• Allow researchers to study phenomena that cannot be produced ethically in a lab

• The use of triangulation increases validity and credibility

• Holistic approach

• Cannot be replicated (low reliability)

• Difficult to generalize to other people

• Cannot establish cause and effect relationships

Protection from undue stress/harm

• Undue stress is a higher level of stress than experienced on a daily basis

• Participants should not be humiliated

• Participants should not be forced to reveal private information

• Nothing should be done to participants that will permanently damage their mental or physical health

Informed consent

• Participants must be told the nature of the study before it begins (what the research is about and what potential problems might arise)

• Participants must be informed of their rights, including the right to withdraw from the study (psychologists should not pressure or coerce participants who no longer want to be in the study and their data must be withdrawn)

• Parents must give consent for children

• Parents or guardians generally give consent for those with mental or physical disabilities if they cannot understand the implications of being in an experiment

• Informed consent is difficult when the nature of the study involves complex terminology (specifically in the biological approach)

Deception

• If a psychologist tells you what an experiment is about, you might change your behavior (demand characteristics)

• Deception includes misinformation and not revealing the entire aim of the study

• Slight deception is allowed in some cases when it doesn’t cause stress to the participants, but its necessity must be justified and approved by an ethics board

Debriefing

• At the end of the experiment, participants must be told the real aims and purpose of the experiment, and any use of deception should be justified to the participants

• Participants should leave the experiment in the same physical and psychological condition they arrived in

• All data must be guaranteed to be anonymized (the identities of the participants must not be revealed when the data is published or with any use of the data after)

Positron emission tomography (PET scan)

• Injection of radioactive dye/glucose into participant (invasive)

• Dye produces gamma rays as glucose is metabolized in the brain

• It is assumed that the more a region of the brain metabolizes glucose, the more active that area of the brain is

• Gamma rays are turned into computer images and color coded based on brain activity

• Used to identify functions such as blood flow, oxygen use, and sugar metabolism, as well as identify activity in specific brain regions

• PET scans can be used to show abnormalities in brain activity that wouldn’t show up on structural images until much later

• The radioactive tracer is low-risk

• Slow (30 min - 2 hours) and poor resolution

Magnetic resonance imaging (MRI)

• Used to find problems in the brain like tumors, bleeding, or structural abnormalities

• Uses a magnetic field and radio waves to map the activity of hydrogen molecules (present in different levels in different parts of the brain)

• Magnetic field aligns spin of hydrogen molecules (present in water)

• When the scanner turns off and the hydrogen molecules return to their normal spin, a radio signal is produced which can then be turned into an image

• Image can be viewed as a slice of the brain or a 3D image (only indicates structure)

• Participants with metal implants cannot go into an MRI

• Ecological validity is not an issue because it is just a picture

• Non-invasive, minimal potential harm, high resolution

Functional magnetic resonance imaging (fMRI)

• Investigates the correlation between certain behaviors and brain activity 

• Also helps determine the impact of medical conditions on brain activity

• Higher resolution than PET scans

• Measures blood flow as an indicator of activity (more active areas need more oxygen)

• Produces a film (demonstrates change over time)

• Participants with metal implants cannot go into an fMRI

General notes about brain imaging

• Sampling bias, because not everyone can fit in or is comfortable with the machine

• Very expensive, limited number of participants

• Not a natural environment (low ecological validity)

• Better than previous methods like lesioning on animals because they are non-invasive

• The use of colors exaggerates results

• Parts of the brain can activate for reasons outside of what is being tested (artefacts)

Localization of function

• Localization of function is the idea that specific parts of the brain are responsible for specific behaviors

• In reality, many brain functions are the result of distributive processing, not localization

Brain stem

Regulates life functions (breathing, heart rate, blood pressure)

Cerebellum

Balance, motor function, speech production, learning (classically conditioned responses)

Cerebral cortex

Largest part of the brain, higher order functions (thought and action), includes:

• Frontal lobe: executive functions (planning, decision making, speech)

• Occipital lobe: visual processing

• Parietal lobe: sensory perception

• Temporal lobe: auditory processing and memory

The limbic system

Processing and regulating memory and emotion, the “emotional brain”, includes:

• Amygdala: emotional memory formation and fear response

• Basal ganglia: habit formation and procedural memory

• Hippocampus: transfer of STM to LTM

• Hypothalamus: homeostasis, emotion, thirst, hunger, circadian rhythm, control of autonomic nervous system, control of pituitary gland

• Nucleus accumbens: addiction and motivation

Neuroplasticity

• Scientists previously thought that the structure of the brain was fixed

• Neuroplasticity is the brain’s ability to change its structure in response to changes within the body or in the environment

• High levels of stimulation and learning opportunities leads to denser neural connections through dendritic branching

• When synapses are repeatedly used, they become stronger and produce greater levels of response, a phenomenon called long-term potentiation

• This leads to increased protein synthesis and changes in gene expression called neural arborization

• When a synapse (connection between neurons) is not used for a long time, it may go through synaptic pruning to increase the efficiency of the brain

Neurotransmission

• Neurotransmitters are natural chemical messengers that pass information between neurons

• An action potential (electrical impulse) travels down the axon of the neuron which causes neurotransmitters in the terminal buttons to be released

• Neurotransmitters fit into receptor sites on the post-synaptic (next neuron) membrane

• They are either broken down by enzymes or reabsorbed into the terminal buttons  through reuptake

• Excitatory neurotransmitters increase the likelihood of a neuron firing through depolarization (acetylcholine)

• Inhibitory neurotransmitters decrease the likelihood of a neuron firing through polarization (GABA)

• Agonists are chemicals that bind to postsynaptic receptor sites to produce a response (all neurotransmitters and some drugs)

• Antagonists block receptor sites so that an action potential can’t be sent down the axon (scopolamine)

Acetylcholine

Aids in memory consolidation in the hippocampus, neurotransmitter

Dopamine

Controls reward and pleasure centers, plays a role in motivation, neurotransmitter

Norepinephrine

Arousal and alertness, neurotransmitter

Serotonin

Sleep, arousal levels, emotion, neurotransmitter

GABA

Inhibits neural activity in the hippocampus and frontal lobe, allows for an increase in cognitive load, neurotransmitter

Hormones

• Hormones are chemicals secreted into the bloodstream by glands in the endocrine system that affect behavior

• They take longer to produce changes than neurotransmitters but the changes last longer

• Hormones bind to target cells that have a receptor site for the hormone to increase or decrease its function

Adrenaline

Secreted by the adrenal glands, arousal and “fight or flight” response, increases heart rate, blood pressure, and respiration, emotional memory formation, hormone

Cortisol

Secreted by the adrenal glands, controls blood sugar levels, regulates metabolism, reduces inflammation, assists in memory formation, hormone

Melatonin

Secreted by the pineal gland, signals relaxation and lower body temperature to aid in sleep, hormone

Neuropeptide Y

Produced by the hypothalamus, acts as a neurotransmitter, stimulates food intake, reduces anxiety and stress, reduces pain perception, affects the circadian rhythm, high levels are linked to high resilience, hormone

Oxytocin

Produced by the hypothalamus and secreted by the pituitary gland, mother/child attachment, social bonding and trust, hormone

Testosterone

Produced by the testes, facilitates aggressive behavior (does not cause it but is linked to it), hormone

Pheromones

• Pheromones are chemicals released into the environment by animals that affect the behavior of members of their own species

• It is still debated whether humans have them

• Primer pheromones cause long-term physiological changes

• Signaling pheromones induce behavioral effects

• Androstadienone (AND): potential male pheromone; found in male semen and sweat

• Estratetraenol (EST): potential female pheromone; found in female urine

Genetics

• Behavioral genetics looks at how both the environment and genetics lead to a behavior

• Genes are the building blocks of complex behaviors

• The diathesis-stress model explains behavior as a genetic predisposition expressed through the stress of life experiences

• Genetics is based on inheritance

• Twin studies look at concordance rate (probability that a trait is in both twins)

• It is assumed that the more genetically similar a pair is the, the more likely they are to both have the trait

• Adoption studies can be used to determine if a trait is genetic or the result of the environment 

• Family (pedigree) studies look at multiple generations to determine whether a trait is inherited

• Association studies look for correlations between genetic variations (markers) and behaviors

• Genome-wide association studies (GWAS) compare the DNA of people with and without a trait to determine potential genetic markers for the trait

• Genetic arguments are correlational

Evolution

• Evolutionary psychologists assume that behaviors are genetic and the result of natural selection

• When genes mutate, advantageous ones are passed through natural selection

• Those who adapt to the environment better are more likely to pass on their genes

• Natural selection does not select behaviors, only the genes that produce a behavior