1. Concepts

Bias is a consistent tendency for thinking, measurement or evidence to lean in one direction. It is not simply a random mistake: some feature of the person, method or context repeatedly makes one interpretation, group or outcome more likely.

Bias can enter at different stages:

• cognitive bias changes how information is noticed or interpreted; an initial number can anchor later estimates
• researcher, participant or sampling bias changes how evidence is produced or who is represented
• cultural, gender or publication bias changes which experiences and findings become visible

Suppose a researcher expects a memory strategy to work. If ambiguous responses are more often scored as correct in the treatment group, the expectation has influenced measurement. A concrete anchoring study found that people given a low starting sequence made a much smaller estimate than people given a high starting sequence, even though both sequences had the same final answer. If the sample also comes from one highly selective school, the evidence may not represent other learners. Neither problem requires dishonesty; bias can operate without awareness.

A surprising result is not automatically biased. To justify that judgement, identify the mechanism that systematically favours one interpretation, group or outcome. The anchoring example is one form of cognitive bias, not a definition of bias as a whole.

A causal claim says that changing one factor produces a change in another. Correlation is evidence of association, but it can also arise from a third variable, reverse direction or coincidence.

A strong causal design controls plausible confounds, establishes temporal order and measures the construct accurately. Random assignment strengthens internal validity; replication and appropriate sampling help judge whether the result transfers.

If sleep and memory scores correlate, stress or workload may affect both. A controlled intervention that changes sleep while measuring the same memory outcome provides stronger causal evidence than a single survey.

Random assignment does not guarantee a representative sample, and a statistically significant association is not automatically a causal effect.

Change is a difference in behaviour, health, learning or development across time or conditions. It may be gradual or sudden, planned or unplanned, and may arise from deliberate intervention, natural maturation, experience or changing circumstances.

Psychologists examine change with evidence across time or repeated conditions and ask what mechanism produced it. Interventions, prevention and health-promotion strategies may alter behaviour, but motivation, opportunity, social context and barriers can affect adoption, resistance and maintenance.

If anxiety scores fall after a school programme, the change could reflect the intervention, maturation, another event, measurement effects or selective dropout. A comparison condition, repeated measurement and evidence of the proposed mechanism make the intervention explanation stronger.

A before-and-after difference does not by itself prove treatment effectiveness. Distinguish natural development from purposeful change, consider agency and context, and check whether the change is valid, sustained and meaningful rather than merely statistically detectable.

Psychological constructs such as stress or memory cannot always be observed directly. Operationalization states exactly how a construct will be manipulated or measured, producing quantitative data such as scores or qualitative data such as interview accounts.

Reliability asks whether a procedure gives consistent results; validity asks whether it measures the intended construct and supports the claim. Direct behavioural or physiological measures and indirect self-reports each have strengths and limitations. Triangulation compares methods, data sources or investigators to test whether conclusions converge.

A study might operationalize stress using a standardized questionnaire score and a clearly defined behaviour during a task. Consistent scoring supports reliability; evidence that the indicators represent stress rather than general discomfort supports validity; an interview can add qualitative meaning and reveal disagreement between measures.

A precise number is not automatically an objective or valid measure. State the construct, operational definition, data type and source, then evaluate reliability, validity, reactivity, bias and whether triangulation genuinely examines the same phenomenon.

A psychological perspective is a way of selecting and explaining phenomena, shaped by assumptions about what matters and how it can be studied.

A biological perspective examines mechanisms such as genes, hormones, neurotransmission or brain systems; a cognitive perspective examines processes such as attention, memory, thinking and decision-making; a sociocultural perspective examines how groups, norms, identities and cultural contexts shape behaviour. Each selects different variables and evidence.

To explain persistent stress, a biological account might investigate physiological regulation, a cognitive account appraisal and coping beliefs, and a sociocultural account social support or cultural expectations. Combining compatible evidence can show interacting mechanisms rather than forcing one explanation to replace the others.

Perspective is not personal opinion and no single perspective is sufficient by default. Tie each explanation to its assumptions, mechanism and evidence, compare what it reveals or overlooks, and avoid reducing a whole person to one level of analysis.

Responsibility means maximizing justified benefit while protecting participants, animals, clients and wider communities from avoidable harm in psychological research, therapy, advice and publication. Ethical judgment continues after formal consent or data collection.

Human research normally requires meaningful informed consent, the right to withdraw, protection from physical or psychological harm, privacy or anonymity where promised, secure data and appropriate debriefing. Deception needs strong justification and debriefing. Research with children, animals, public behaviour or socially sensitive topics requires additional safeguards and proportional cost-benefit evaluation.

Before a study uses incomplete disclosure, reviewers should ask whether the question can be answered without deception, whether risk is minimal, how withdrawal remains possible and how participants will be debriefed. When reporting findings, researchers should avoid stigmatizing a group, state limitations and consider responsible advocacy or correction of misuse.

Potential scientific or social benefit does not automatically override autonomy, safety or dignity, and anonymity is different from confidentiality. Ethical approval is a minimum process, not proof that every application or public interpretation of the findings is responsible.