PSYCHOLOGICAL RESEARCH METHODS
How Psychologists Study Human Behavior and Mental Processes
CORE IDEA: Psychology uses systematic research methods to test ideas about behavior and
mental processes.
01 WHY SCIENTIFIC RESEARCH?
Human intuition is useful, but it is not always reliable. Psychology uses scientific methods to
reduce the influence of bias, overconfidence, and misleading patterns.
REMEMBER Feeling certain does not mean being correct.
The central movement of scientific thinking:
INTUITION → QUESTION → HYPOTHESIS → RESEARCH → EVIDENCE → CONCLUSION
02 THREE PROBLEMS WITH INTUITION
Hindsight Bias — After an event happens, people may feel that they “knew it all along.”
Overconfidence — People may be more confident in their judgments than the evidence
justifies.
Seeing patterns in random events — Humans naturally look for patterns, even when a
sequence is random.
MEMORY TRICK Hindsight = AFTER the event, “I knew it!”
Example: A sequence such as T–T–T–T–T can look unusual, but a random process can produce
it without any special meaning.
03 SCIENTIFIC METHOD — BIG PICTURE
Question → Theory → Hypothesis → Operationalization → Research → Data → Analysis →
Conclusion → Replication
This sequence connects the entire chapter: researchers begin with a question, make a
testable prediction, define what they will measure, collect evidence, analyze it, and see
whether findings can be reproduced.
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, 04 THEORY, HYPOTHESIS & OPERATIONALIZATION
THEORY
A broad explanation that organizes observations and generates predictions.
HYPOTHESIS
A specific prediction that can be tested.
SHORTCUT Theory = BIG explanation | Hypothesis = TESTABLE prediction
Example:
Theory: Sleep affects cognitive functioning.
Hypothesis: Adults who sleep 8 hours will perform better on a memory test than adults who
sleep 4 hours.
05 OPERATIONAL DEFINITIONS
Researchers must define exactly what an abstract idea means in measurable terms.
“Caffeine makes people think better” is too vague. “Think better” might mean faster reaction
time, higher test score, faster problem solving, better memory, or fewer errors.
OPERATIONALIZATION = turning an abstract idea into something measurable.
Example: Thinking better = number of correct answers on a standardized problem-solving
task completed within 10 minutes.
06 REPLICATION
One study does not automatically establish a scientific fact. Researchers should attempt to
replicate findings.
Replication → Reproducibility → Stronger scientific evidence
KEY POINT If multiple studies produce consistent results under appropriate conditions, confidence
in the finding increases.
07 DESCRIPTIVE RESEARCH
Descriptive research mainly answers: “What is happening?” It does not necessarily tell us
why something happens.
METHOD WHAT IT DOES KEY LIMITATION / USE
Case study Detailed investigation of one person, Detailed; may have limited
group, or case. generalizability.
Naturalistic Observes behavior in a natural Real-world behavior; less control.
observation environment without manipulating it.
Survey / interview Asks participants about attitudes, Question wording can influence
opinions, experiences, behaviors, or responses.
beliefs.
Archival research Analyzes information that already Useful existing data; variables may be
exists. limited.
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How Psychologists Study Human Behavior and Mental Processes
CORE IDEA: Psychology uses systematic research methods to test ideas about behavior and
mental processes.
01 WHY SCIENTIFIC RESEARCH?
Human intuition is useful, but it is not always reliable. Psychology uses scientific methods to
reduce the influence of bias, overconfidence, and misleading patterns.
REMEMBER Feeling certain does not mean being correct.
The central movement of scientific thinking:
INTUITION → QUESTION → HYPOTHESIS → RESEARCH → EVIDENCE → CONCLUSION
02 THREE PROBLEMS WITH INTUITION
Hindsight Bias — After an event happens, people may feel that they “knew it all along.”
Overconfidence — People may be more confident in their judgments than the evidence
justifies.
Seeing patterns in random events — Humans naturally look for patterns, even when a
sequence is random.
MEMORY TRICK Hindsight = AFTER the event, “I knew it!”
Example: A sequence such as T–T–T–T–T can look unusual, but a random process can produce
it without any special meaning.
03 SCIENTIFIC METHOD — BIG PICTURE
Question → Theory → Hypothesis → Operationalization → Research → Data → Analysis →
Conclusion → Replication
This sequence connects the entire chapter: researchers begin with a question, make a
testable prediction, define what they will measure, collect evidence, analyze it, and see
whether findings can be reproduced.
1
, 04 THEORY, HYPOTHESIS & OPERATIONALIZATION
THEORY
A broad explanation that organizes observations and generates predictions.
HYPOTHESIS
A specific prediction that can be tested.
SHORTCUT Theory = BIG explanation | Hypothesis = TESTABLE prediction
Example:
Theory: Sleep affects cognitive functioning.
Hypothesis: Adults who sleep 8 hours will perform better on a memory test than adults who
sleep 4 hours.
05 OPERATIONAL DEFINITIONS
Researchers must define exactly what an abstract idea means in measurable terms.
“Caffeine makes people think better” is too vague. “Think better” might mean faster reaction
time, higher test score, faster problem solving, better memory, or fewer errors.
OPERATIONALIZATION = turning an abstract idea into something measurable.
Example: Thinking better = number of correct answers on a standardized problem-solving
task completed within 10 minutes.
06 REPLICATION
One study does not automatically establish a scientific fact. Researchers should attempt to
replicate findings.
Replication → Reproducibility → Stronger scientific evidence
KEY POINT If multiple studies produce consistent results under appropriate conditions, confidence
in the finding increases.
07 DESCRIPTIVE RESEARCH
Descriptive research mainly answers: “What is happening?” It does not necessarily tell us
why something happens.
METHOD WHAT IT DOES KEY LIMITATION / USE
Case study Detailed investigation of one person, Detailed; may have limited
group, or case. generalizability.
Naturalistic Observes behavior in a natural Real-world behavior; less control.
observation environment without manipulating it.
Survey / interview Asks participants about attitudes, Question wording can influence
opinions, experiences, behaviors, or responses.
beliefs.
Archival research Analyzes information that already Useful existing data; variables may be
exists. limited.
2
