Psychological Science and Research Methods

Purpose of psychological researchPsychology is a “soft science” and “social

science” – humans are not predictable or reliable (individual differences)

Psychologists do research to:1. Study development and environmental factors and the role

they play in individuals' mental health.2. Study people with specific psychological disorders, symptoms,

or characteristics.3. Develop tests to measure specific psychological phenomenon.4. Develop treatment approaches to improve individuals' mental

health

Basic and applied research

Goals of psychological researchDescribe (objectivity)Understand (why?)Predict (the past predicts the future)Control (manipulation/intervention)Improve

Compare

How do we do research?Inductive Reasoning Deductive

Reasoning (bottom-up) (top-down)

Scientific methodObservation : identifyHypothesisDesign ResultsConclusionCommunication

• CYCLICAL PROCESS

Scientific method contd.A theory is a system of interrelated ideas

used to explain a set of observationsA hypothesis is a specific prediction or

tentative explanation Null hypothesis Alternative hypothesis

Experiments are designed to test and disprove hypotheses and theories and advance knowledge and understanding.

Types of researchDescriptive

naturalistic observation, case study, surveys/questionnaires/interviews

Correlational relationship/connection between two

or more variablesExperimental

causal relationship between two or more variables

Experimental ResearchMost scientific – objective and reliableEstablish cause and effect relationship between two

or more variablesVariables: (operationalization)

IV – independent variable (manipulated) DV – dependent variable (“depends” upon IV) EV – extraneous variable, confounding variable

Participants (population and sample; experimental group and control group)

Settings (experimental control and standardization)

Features of Experimental DesignTemporal precedence of IV : IV must

come before the DVEstablishment of cause-and-effect

relationship No plausible alternative explanations

(third variable problem)Random assignment

If any one of these is not present, the study becomes a quasi-experiment.

Threats/Biases in Experimental ResearchSampling bias/Selection bias

– affects reliability and validityPlacebo effect

– influencing of performance due to the subject’s belief about the results

Experimenter biasSocial desirability bias Hawthorne effectType I errorType II error

Countering biases in experimental designRandom samplingRandom assignment to groups and equal

treatment of groupsControlled settingsSingle-blind Double-blindDeceptionMultiple observers

Evaluating experimental researchAdvantages: ScientificStandardized and controlledCausal relationshipsReplicableHigh internal validityLimitations:ArtificialityDemand characteristics and evaluation

apprehensionLow external validity

Issues to considerReliability - replicabilityValidity – generalizability

Internal/experimental validity vs. External/ecological validity

Experimental realism vs. mundane realism

Ethical issues