2.1 What is scientific inquiry? Careful scientific research, way of finding answers to empirical questions. Scientific
method: systematic procedure of observing and measuring phenomena to answer questions about what, when, cause,
why; involves interaction between theories, hypotheses, research.
Scientific method depends on theories, hypotheses, research: theory: explanation of how phenomenon works,
interconnected ideas/concepts, used to explain prior observations, make predictions about future. Hypothesis:
specific, testable prediction of what should be observed if theory is correct. Research: systematic, careful
collection of data: objective observations/measurements, provide way to test hypothesis. Cyclical process
necessary for good research, theory continually refined by new hypotheses and tested by new methods
o Theories should generate hypotheses: good theory produces wide variety of testable hypotheses, e.g.
Piaget’s stage theory vs. Freud’s interpretation of dreams.
Serendipity: unexpected finding things are valuable. Wiesel and Hubel: brain cells respond to lines and edges
2.2 What types of studies are used in psychological research? Designs differ in extent to which researcher has control
over variable; amount of control determines type of conclusions that can be drawn. Variable: something in world that
can vary and be measured. Operational definitions: identifying variables and quantifying them so they can be
measured; each variable specified in way that makes it possible to record quantity (e.g., fingers-to-nose distance).
Descriptive/observational studies: observing and noting behavior to provide systematic and objective
analysis of behavior. Two types of observation include naturalistic: passive, no attempt to change behavior,
and participant: researcher is actively involved in situation (problems: loss of objectivity, change in
behavior). Descriptive techniques valuable in early stages of research to see if phenomenon exists.
Longitudinal: development design that studies same participants multiple times over period of time
(expensive, lengthy, risky) Cross-sectional: compares participants in different groups at the same time (faster,
cheaper, but possibility of unidentified variable – cohort effect).
o Observer bias: systematic errors in observation due to observer’s expectations, especially cultural.
Experimenter expectancy effect: change in behavior of observee due to expectations of observer. Can
be prevented if person running study is blind.
Correlational studies examine how variables are related in world, no attempt to alter or assign causation.
o Directionality problem: cannot know which variable causes changes in which, e.g. sleep and stress
o Third variable problem: researcher cannot directly manipulate variables, so cannot be confident that
another unmeasured variable is not actual cause of differences in variables, e.g. instead of A causing B,
it is possible that C causes A and B. Drinking before driving correlated to distraction; but stress causes
some people to drink and stress causes some people to be distracted.
o Ethical reasons for using correlational designs: cannot induce trauma; must find people with PTSD
o Making predictions: correlational studies can be used to determine that two variables are associated,
and by establishing connections, researchers can make predictions.
An experiment tests causal hypotheses by measuring and manipulating variables, investigator has maximal
control. Control group: comparison, participants receive no intervention. Experimental groups: receive
intervention/treatment. Independent variable: manipulated. Dependent variable: measured. Benefit of
experiment is that researcher can study causal relationship between two variables.
o Establishing causality: good experiment must have rigorous control: steps taken to minimize
possibility that anything other than independent variable will affect outcome. Confound: anything that
affect dependent variable, may unintentionally vary between study’s different experimental conditions.
Researcher needs to ensure that only thing that varies is independent variable. Control is foundation of
experimental approach b/c it allows researcher to rule out alternative explanations for data.
Random sampling and random assignment are important for research: important issue is selecting participants
so that finding generalize to people beyond participants. Population: everyone in group you want to know
about. Sample: subset of population that you actually study. Sampling is process of selection, best if random,
giving each member of population equal chance of being chosen to participate, but usually convenience. In
random sampling, possible confound is preexisting differences between groups assigned to different
conditions. External validity: degree to which findings of experiment can be generalized outside lab.
o Selection bias: unintended differences between participants in different groups
o Random assignment: each participant