IB Psychology HL key terms

A chemical messenger released by a neuron that travels across a synapse and alters the activity of another neuron, muscle or gland; serotonin and dopamine are examples studied in biological psychology.

The idea that specific brain areas are specialised for particular cognitive or behavioural functions, such as the hippocampus for memory formation or Broca's area for speech production.

The brain's ability to reorganise its neural connections and structures in response to experience, learning, injury or environmental change, allowing adaptation across the lifespan.

A brain structure in the medial temporal lobe that is crucial for forming new declarative memories and for spatial navigation; damage can cause anterograde amnesia.

Functional magnetic resonance imaging; a non-invasive brain scan that measures changes in blood oxygenation to infer which brain regions are active during a task.

A research design comparing monozygotic (identical) and dizygotic (fraternal) twins to estimate how much a trait is influenced by genetic versus environmental factors.

The study of how environmental factors can alter gene expression without changing the DNA sequence, helping explain why identical twins may develop different traits or disorders.

A hormone released by the adrenal glands in response to stress; it mobilises energy and can affect memory and immune function when levels remain elevated.

A mental framework or set of organised expectations that helps people interpret new information, guide attention and fill in missing details, but can also distort memory.

Baddeley and Hitch's model proposing that short-term storage is not a single store but includes a central executive controlling limited capacity subsystems such as the phonological loop and visuospatial sketchpad.

Atkinson and Shiffrin's model of memory as a sequence of sensory memory, short-term memory and long-term memory, with attention and rehearsal moving information between stores.

The view that remembering involves rebuilding past events from stored schemas and fragments rather than replaying exact recordings, so memories can be altered by later information.

The tendency to seek, interpret and remember information that supports existing beliefs while ignoring or downplaying evidence that contradicts them.

A mental shortcut in which people judge the likelihood or frequency of an event by how easily examples come to mind, often influenced by vivid or recent experiences.

The idea that thinking involves two systems: a fast, automatic, intuitive System 1 and a slower, deliberate, analytical System 2, which interact in judgement and decision making.

Tajfel and Turner's theory that people derive part of their self-concept from group memberships and are motivated to favour their in-group over out-groups to maintain positive identity.

A change in behaviour or beliefs in response to real or imagined group pressure, such as Asch's line-judgement studies where participants agreed with a clearly wrong majority.

Compliance with a direct order from an authority figure, classically studied by Milgram, where situational factors such as perceived legitimacy and proximity influence whether people obey.

A generalised belief about the characteristics of a group and its members, which can be positive or negative and may lead to prejudice and discrimination.

A cultural dimension describing whether a society emphasises personal goals, independence and uniqueness (individualism) or group goals, interdependence and harmony (collectivism).

The process of cultural and psychological change that occurs when individuals or groups come into sustained contact with a different culture, often involving strategies such as integration, assimilation, separation or marginalisation.

An explanation of mental disorders proposing that a genetic or psychological vulnerability (diathesis) only leads to disorder when combined with stressful environmental triggers.

A negative social label that links a person to undesirable characteristics, often leading to discrimination, social exclusion and reluctance to seek help for mental health problems.

A lasting emotional bond between an infant and a caregiver, studied through patterns such as secure, insecure-avoidant and insecure-resistant attachment, which may influence later relationships.

The ability to attribute mental states-such as beliefs, desires and intentions-to oneself and others, and to understand that others may hold beliefs different from reality.

In stress research, the cognitive evaluation of whether an event is a threat or a challenge and whether one has the resources to cope, shaping the emotional and physiological response.

A state of physiological and psychological activation or alertness; in sport psychology, the inverted-U hypothesis suggests performance is best at moderate arousal and suffers when arousal is too low or high.

The extent to which a study's results can be attributed to the manipulation of the independent variable rather than to confounding variables or flaws in the research design.

The degree to which findings from a study can be generalised to real-world settings, tasks and everyday behaviour outside the controlled research environment.

The consistency and repeatability of a measurement or research procedure-for example, whether a questionnaire yields similar scores when administered again or when scored by different researchers.

Cues in a study that lead participants to guess the researcher's aims and change their behaviour, potentially distorting results and threatening the study's validity.

Using two or more independent methods, data sources or researchers to study the same phenomenon, so that findings can be cross-checked and the credibility of conclusions strengthened.

In qualitative research, the researcher's critical examination of how their own background, assumptions and role may shape the research process, data and interpretations.

A qualitative method for identifying, analysing and reporting patterns or themes across data such as interview transcripts, involving repeated reading, coding and interpreting meaning.

A precise, measurable description of how a variable will be observed or manipulated in a study, such as defining aggression as the number of hits recorded in a five-minute observation.

An unwanted variable that changes systematically with the independent variable and can therefore provide an alternative explanation for the study's results.

Summaries of data such as means, medians, ranges and standard deviations that describe the main features of a sample without drawing inferences about a wider population.

The ethical requirement that participants voluntarily agree to take part after being told the purpose, procedures, risks and right to withdraw, usually recorded in a written or verbal agreement.