Psychology research pillar · 26 definitions
Psychology research methods
Clear, citable definitions of the concepts that underpin rigorous psychology research — the cognitive biases that threaten objective judgement, the psychometric instruments used to measure mind and behaviour, and the reliability and validity standards that decide whether a measurement can be trusted. Measurement science, not quizzes or advice.
Cognitive biases and judgement
A large body of research shows that human judgement departs from rationality in systematic ways. The cognitive-bias literature — confirmation bias, anchoring, the availability heuristic, the sunk-cost fallacy and the Dunning–Kruger effect — explains many of these patterns, and is exactly why research methods build in safeguards such as blinding and pre-registration.
Measuring psychological constructs
Psychology cannot measure its subjects directly, so it relies on psychometric instruments — from Likert scales to intelligence tests and personality assessments. Each instrument is only as good as its reliability and validity, which is why this pillar examines what instruments such as the MBTI actually measure rather than treating them as quizzes.
Ethics and rigour
Research with people carries ethical obligations, beginning with informed consent. Combined with sound measurement and transparent reporting, these principles are what make psychological findings credible. The definitions below cover the biases, instruments, developmental concepts and ethical foundations of the field.
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Psychology research definitions
Confirmation bias
What is confirmation bias?
Confirmation bias is the tendency to search for, interpret, favour, and recall information in a way that confirms what we already believe, while giving less weight to evidence that contradicts those beliefs.
Read →Sunk cost fallacy
What is the sunk cost fallacy?
The sunk cost fallacy is the tendency to keep investing in a course of action because of resources already spent, even when continuing is no longer the best choice and those past costs cannot be recovered.
Read →Dunning-Kruger effect
What is the Dunning-Kruger effect?
The Dunning-Kruger effect describes the finding that people with low competence in a domain tend to overestimate their ability, in part because the skills needed to perform well are also the skills needed to judge performance accurately.
Read →Cognitive bias
What is cognitive bias?
A cognitive bias is a systematic pattern of deviation from rational judgement, in which the way the mind processes information leads to errors that recur predictably across people and situations.
Read →Anchoring bias
What is anchoring bias?
Anchoring bias is the tendency to rely too heavily on the first piece of information encountered — the anchor — when making estimates or decisions, so that later judgements stay too close to that initial value.
Read →Availability heuristic
What is the availability heuristic?
The availability heuristic is a mental shortcut in which people judge how likely or common something is by how easily examples come to mind, so vivid or recent events are estimated to be more frequent than they really are.
Read →Hindsight bias
What is hindsight bias?
Hindsight bias is the tendency, once an outcome is known, to see it as having been predictable all along, so that past events feel more obvious and inevitable than they actually were before they happened.
Read →Likert scale
What is a Likert scale?
A Likert scale is a psychometric rating scale used in surveys to measure attitudes or opinions, in which respondents indicate how far they agree or disagree with a statement on an ordered set of response options.
Read →What is psychology?
What is psychology?
Psychology is the scientific study of mind and behaviour, using systematic, empirical methods to understand how people and animals perceive, think, feel, learn, and act, both as individuals and in groups.
Read →IQ test
What does an IQ test measure?
An IQ test is a standardised instrument that estimates aspects of cognitive ability relative to a reference population; understanding what it measures means examining its standardisation, reliability, validity, and well-documented limitations.
Read →MBTI
What is the Myers-Briggs Type Indicator?
The Myers-Briggs Type Indicator (MBTI) is a self-report questionnaire that sorts people into sixteen personality types across four dichotomies; psychologists scrutinise it for its construct validity and test-retest reliability.
Read →Personality assessment
What is personality assessment?
Personality assessment is the measurement of stable patterns of thinking, feeling, and behaving, using methods that range from self-report questionnaires to observation, evaluated by their reliability and validity.
Read →Cognitive development
What is cognitive development?
Cognitive development is the study of how thinking, reasoning, memory, and problem-solving emerge and change across the lifespan, classically described by Piaget's stage theory and contrasted with Vygotsky's sociocultural account.
Read →Informed consent
What is informed consent in research?
In research ethics, informed consent is the voluntary, informed, and competent agreement of a person to take part in a study, given after they understand its purpose, procedures, risks, and their right to withdraw.
Read →Cognitive assessment
What is cognitive assessment?
Cognitive assessment is the systematic measurement of cognitive functions such as memory, attention, language, and reasoning, using standardised instruments evaluated for their reliability and validity in research.
Read →Reliability and validity
What are reliability and validity?
Reliability and validity are the two core criteria of measurement quality in psychometrics: reliability is the consistency of a measure, and validity is whether it actually measures what it claims to measure.
Read →Halo effect
What is the halo effect?
The halo effect is a cognitive bias in which an overall positive impression of a person or thing colours judgements of their specific, unrelated qualities, so that one favourable trait spills over into the rest.
Read →Framing effect
What is the framing effect?
The framing effect is a cognitive bias in which people reach different decisions depending on how equivalent information is presented, such as whether an option is described in terms of gains or of losses.
Read →Negativity bias
What is negativity bias?
Negativity bias is the tendency for negative information, events, and experiences to have a greater effect on judgement and memory than equally strong positive information, so that "bad" weighs more heavily than "good".
Read →Optimism bias
What is optimism bias?
Optimism bias is the tendency to overestimate the likelihood of positive outcomes and underestimate the likelihood of negative ones for oneself, so that people expect a better future than the evidence justifies.
Read →Self-serving bias
What is self-serving bias?
Self-serving bias is the tendency to attribute one’s successes to internal factors such as ability or effort, while attributing failures to external factors such as luck, circumstances, or other people.
Read →Cognitive dissonance
What is cognitive dissonance?
Cognitive dissonance is the mental discomfort that arises from holding two or more conflicting beliefs, attitudes, or behaviours, which motivates people to reduce the inconsistency by changing one of them.
Read →Bandwagon effect
What is the bandwagon effect?
The bandwagon effect is the tendency to adopt beliefs or behaviours because many other people have already done so, with the rate of adoption increasing as the number who have adopted grows.
Read →Big Five personality
What is the Big Five personality model?
The Big Five is the leading scientific model of personality, describing individual differences across five broad trait dimensions — openness, conscientiousness, extraversion, agreeableness, and neuroticism — remembered by the acronym OCEAN.
Read →Attachment theory
What is attachment theory?
Attachment theory is a framework in developmental psychology describing how early emotional bonds between infants and caregivers shape patterns of relating, studied through methods such as the Strange Situation.
Read →Social desirability bias
What is social desirability bias?
Social desirability bias is the tendency for survey respondents to answer in ways they believe will be viewed favourably by others, over-reporting approved behaviours and under-reporting disapproved ones, threatening the validity of self-report data.
Read →Common questions
Psychology research FAQ
What is a cognitive bias?+
A cognitive bias is a systematic pattern of deviation from rational judgement, in which the way people process information leads to predictable errors. Examples include confirmation bias, anchoring and the availability heuristic, studied within the heuristics-and-biases research programme.
Does an IQ or personality test really measure what it claims?+
It depends on the instrument's psychometric properties — its reliability (consistency) and validity (whether it measures the intended construct). Some instruments, such as well-standardised intelligence tests, have strong evidence; others, such as type-based personality indicators, face significant validity and reliability criticism. These pages take that measurement-science view rather than offering quizzes.
What is the difference between reliability and validity?+
Reliability is the consistency of a measure — whether it gives the same result under the same conditions. Validity is whether the measure actually captures the construct it claims to. A measure can be reliable without being valid, but a valid measure must also be reliable.
Is this a clinical or mental-health resource?+
No. These pages define psychology research-methods and measurement concepts. They are not clinical, diagnostic or mental-health advice. Topics such as informed consent are scoped to research ethics, not medical or legal consent.
How does this relate to CASRAI standards?+
CASRAI is a research-standards body. Sound psychological research depends on rigorous measurement, transparent reporting and research integrity — the standards layer that makes findings reproducible and trustworthy across the research ecosystem.
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