Psychology Research Methods, Brain Studies, and Case Examples

Independent Samples Design

Different participants are used in each condition of the experiment. Example: One group drinks coffee, another doesn't. Pro: No order effects. Con: Participant differences.

Repeated Measures Design

The same participants do all conditions. Example: The same people are tested with and without coffee. Pro: No individual differences. Con: Order effects (tiredness or practice).

Independent Variable (IV)

The factor that is manipulated by the experimenter. Example: Whether a person drinks coffee.

Dependent Variable (DV)

The outcome measured in an experiment. Example: Memory test results.

Ethical Guidelines (CARDUD)

Consent, Anonymity ,Right to withdraw ,Deception ,Undue stress or harm ,Debriefing

True Experiment

Researcher randomly assigns participants and manipulates IV. Example: Randomly assigning people to caffeine or no caffeine groups.

Quasi Experiment

Uses existing groups (no random assignment). Example: Comparing people with depression vs. those without.

Volunteer (Self-Selected) Sample

Participants volunteer to join the study. Pro: Motivated participants. Con: Not representative.

Convenience (Opportunity) Sample

Participants chosen because they're easy to access. Pro: Quick and simple. Con: May be biased.

Random Sample

Everyone has an equal chance of being chosen. Pro: Reduces bias. Con: Hard to organize.

Stratified Sample

Population divided into subgroups (e.g., age, gender) and sampled proportionally. Pro: More representative. Con: Complex process.

Extraneous/Confounding Variables

Uncontrolled factors that affect the DV. Controlled by: Random assignment, same environment, standardized procedures.

Participant Biases

Demand characteristics: Acting how they think they should. Social desirability: Trying to look good. Placebo effect: Expectations affect results.

Internal Validity

The IV truly caused the change in the DV.

External Validity

Results can generalize to other people/situations.

Ecological Validity

How realistic or natural the study setting is.

Construct Validity

Whether the test actually measures what it claims to.

Perspectives in Psychology

Biological: Brain/genetics affect behavior. Cognitive: Thoughts influence behavior. Sociocultural: Society and culture shape behavior.

Behaviorist

Behavior learned through rewards/punishment.

Arguments FOR Animal Models

Can test things unethical for humans; Short life cycles for studying changes; Controlled environments.

Arguments AGAINST Animal Models

Brains differ from humans; Ethical concerns; Lab stress changes behavior.

Anthropomorphism

Giving animals human traits/emotions. Example: Saying a rat feels 'guilty.'

The 3 R's (Animal Research Ethics)

1. Replacement - use alternatives if possible; 2. Reduction - use fewer animals; 3. Refinement - minimize pain and stress.

Skepticism of Brain Scans

Can be misinterpreted; Expensive; Don't always show thoughts or feelings accurately.

MRI (Structural Scan)

Shows brain structure in detail.

fMRI (Functional Scan)

Shows active brain areas during tasks (blood flow changes).

Ways We Study the Brain

1. Brain scans (MRI, fMRI, PET); 2. Animal research; 3. Case studies (e.g., HM, EP); 4. Post-mortem exams.

Neuroplasticity

The brain's ability to reorganize and form new connections.

Aphasia

Loss of ability to speak or understand language (due to brain damage).

Cortical Remapping

When one brain area takes over functions of a damaged area.

Patient H.M. (Henry Molaison)

Had surgery removing his hippocampus to stop seizures. Couldn't form new long-term memories (anterograde amnesia) but kept old ones and motor skills. Showed the hippocampus is vital for forming new memories.

Patient E.P. (Eugene Pauly)

Lost his hippocampus due to a virus. Couldn't make new conscious memories but learned new habits automatically. Proved procedural and declarative memory are stored in different brain systems.

Harris & Fiske (2006)

Used fMRI to see how people respond to social groups. When participants viewed homeless or drug-addicted people, brain areas for empathy were less active. Showed how stereotypes cause dehumanization in the brain.

Rosenzweig, Bennett & Diamond (1972)

Rats in enriched environments (toys, others) developed thicker cortexes than isolated rats. Showed experience and environment can physically change the brain — evidence for neuroplasticity.

Maguire (2000) - London Taxi Driver Study

Taxi drivers had larger hippocampi than non-drivers due to memorizing city maps. Proved that the brain changes with experience — strong evidence for neuroplasticity.