Psychology Research Methods and Data Analysis Key Terms

Experiment

Research method that manipulates an independent variable to determine cause-and-effect

Non-experimental research

Describes relationships without manipulating variables

Independent Variable (IV)

Variable manipulated by the researcher

Dependent Variable (DV)

Variable measured; outcome

Confounding variable

Uncontrolled variable that may affect results

Control variable

Factor kept constant

Random assignment

Assigning participants to groups by chance (needed for causation)

Random sampling

Selecting participants randomly from a population

Population

Entire group being studied

Sample

Subset of the population

Representative sample

Accurately reflects population

Convenience sample

Easily available participants

Sampling bias

Sample does not represent population

Generalizability

Ability to apply results to a larger population

Experimental group

Receives treatment

Control group

Does not receive treatment

Placebo group

Receives fake treatment

Placebo effect

Change due to belief, not treatment

Single-blind procedure

Participants don't know group assignment

Double-blind procedure

Participants and researchers don't know group assignment

Experimenter bias

Researcher expectations influence results

Case study

In-depth study of one individual or group

Naturalistic observation

Observing behavior in real-world settings

Correlation

Relationship between two variables (≠ causation)

Positive correlation

Variables increase together

Negative correlation

One increases, other decreases

Correlation coefficient (r)

Strength and direction of relationship (-1 to +1)

Directionality problem

Can't determine which variable causes the other

Third-variable problem

Unmeasured variable affects both

Scatterplot

Visual representation of correlation

Survey

Self-report method using questionnaires

Framing

How question wording influences responses

Social desirability bias

Responding in socially acceptable ways

Self-report bias

Inaccurate answers

Quantitative data

Numerical data (Likert scales)

Qualitative data

Descriptive data (interviews)

Hypothesis

Testable prediction

Falsifiability

Must be able to disprove hypothesis

Operational definition

Exact definition of a variable

Replication

Repeating a study to confirm results

Peer review

Evaluation by experts

Meta-analysis

Combines results from many studies

Mean

Average

Median

Middle score

Mode

Most frequent score

Range

Highest - lowest

Standard deviation

Spread of scores

Normal distribution

Symmetrical bell curve

Positive skew

Tail to the right

Negative skew

Tail to the left

Bimodal distribution

Two peaks

Informed consent

Participants know risks

Informed assent

Permission from minors

Protection from harm

Minimize risk

IRB

Reviews ethical standards

APA ethical guidelines

Protect participants

Charles Darwin

Natural selection

Adaptive traits

Traits increasing survival

Central nervous system (CNS)

Brain & spinal cord

Peripheral nervous system (PNS)

Nerves outside CNS

Somatic nervous system

Voluntary movement

Autonomic nervous system

Involuntary actions

Sympathetic

Arouses body

Parasympathetic

Calms body

Dendrites

Receive messages

Cell body (soma)

Processes info

Axon

Sends signal

Myelin sheath

Speeds transmission

Terminal buttons

Release neurotransmitters

Action potential

Neural firing

Synapse

Gap between neurons

Neurotransmitters

Chemical messengers

Agonist

Mimics neurotransmitter

Antagonist

Blocks neurotransmitter

Reuptake

Neurotransmitter reabsorption

Hormones

Chemical messengers in bloodstream

Pituitary gland

Master gland

Frontal lobe

Decision-making, motor control

Parietal lobe

Touch, spatial awareness

Temporal lobe

Hearing, language

Occipital lobe

Vision

Broca's area

Speech production

Wernicke's area

Language comprehension

Left hemisphere

Language, logic

Right hemisphere

Spatial, creativity

EEG

Electrical brain activity

fMRI

Brain activity via blood flow

PET scan

Metabolic activity

Lesioning

Tissue damage study

Split-brain research

Corpus callosum severed

Neuroplasticity

Brain's ability to reorganize

Depressants

Slow CNS (alcohol)

Stimulants

Speed up CNS (caffeine)

Tolerance

Need more for same effect

Withdrawal

Symptoms when stopping

Addiction

Compulsive drug use

REM sleep

Dreaming, brain activity

NREM sleep

Deep sleep

Sleep cycle

~90 minutes

Insomnia

Difficulty sleeping