Cambridge International AS & A-Level Psychology – Key Vocabulary

A comprehensive set of vocabulary flashcards covering key psychological terms, research methods, statistical concepts and study-specific constructs from the Cambridge International AS & A-Level Psychology Study and Revision Guide.

Biological psychology

An approach that explains behaviour, cognitions and emotions in terms of brain functioning, hormones, genetics and evolution.

Ultradian rhythms

Bodily cycles that repeat more than once every 24 hours, such as the 90-minute sleep cycle of REM and NREM stages.

Rapid Eye Movement (REM) sleep

A sleep stage with low-amplitude, high-frequency brain waves, rapid eye movements, muscle paralysis and frequent dreaming.

Non-REM (NREM) sleep

Sleep stages 1–4 characterised by slower brain waves; dreaming is less common than in REM.

Electroencephalography (EEG)

A technique that records electrical activity of the brain via scalp electrodes to identify sleep stages or other neural patterns.

Objective measurement

Data collection free from personal bias, often numerical or instrument-based, enabling replication.

Reliability

The consistency of a measurement or study, demonstrated when it produces similar results under the same conditions.

Validity

The extent to which a method measures what it claims to measure, producing accurate, genuine findings.

Objectivity

Freedom from researcher bias in collecting or interpreting data, often achieved through quantification or mechanical recording.

Generalisability

The degree to which findings from a sample can be applied to the wider target population or other settings.

Nature–nurture debate

Discussion over the relative influence of inherited biological factors versus environmental and cultural experiences on behaviour.

Participant variable

Individual characteristic (e.g., age, IQ) that may influence study results if not controlled.

Situational variable

Environmental factor (e.g., temperature, noise) that can affect participants’ behaviour in a study.

Independent variable (IV)

The factor an experimenter deliberately manipulates to observe its effect on the dependent variable.

Dependent variable (DV)

The outcome that is measured in an experiment to assess the effect of the independent variable.

Laboratory experiment

A study conducted in a controlled indoor setting with high control of extraneous variables.

Field experiment

An experiment carried out in a natural environment where some variables are manipulated but extraneous factors are less controlled.

Independent measures design

Experimental design in which separate groups of participants experience different conditions of the IV.

Repeated measures design

Design where the same participants take part in all conditions of the IV, controlling participant variables.

Matched pairs design

Design where participants are paired on relevant variables, and each member of a pair is placed in different conditions.

Standardisation

Keeping procedures and instructions identical for all participants to improve reliability and replicability.

Demand characteristics

Cues that reveal the study’s purpose and may lead participants to change their behaviour.

Social desirability bias

Tendency for respondents to answer questions in a manner that will be viewed favourably by others.

Random allocation

Assigning participants to conditions by chance to control participant variables.

Counterbalancing

Altering the order of conditions for different participants to control order effects in repeated measures designs.

Randomisation

Using chance to order materials or allocate tasks, reducing systematic bias within a study.

Correlation

A non-experimental method assessing the relationship between two measured variables (co-variables).

Co-variable

One of the two measured variables in a correlational study that may relate to the other.

Directional hypothesis

Prediction that states the expected direction of the relationship or difference between variables.

Non-directional hypothesis

Prediction that a relationship or difference exists but does not state its direction.

Null hypothesis

Statement predicting no significant relationship or difference; results are due to chance.

Placebo

An inactive substance or procedure given to control groups to assess the effect of expectancy.

Single-blind design

Procedure in which participants are unaware of which condition or treatment they receive.

Double-blind design

Procedure in which both participants and researchers collecting data are unaware of group allocations.

Randomised control trial (RCT)

Clinical study where participants are randomly assigned to experimental or placebo groups, often double-blind, to test interventions.

Questionnaire

A self-report instrument comprising written questions to gather data on attitudes, beliefs or behaviours.

Closed question

Question offering fixed response options, producing quantitative data (e.g., yes/no, rating scales).

Open question

Question inviting free, detailed responses, yielding qualitative data.

Structured interview

Interview using a fixed set and order of predetermined questions.

Semi-structured interview

Interview combining fixed questions with opportunities for follow-up probes.

Unstructured interview

Informal interview guided by topics where questions vary according to participant responses.

Psychometric test

Standardised, reliable and valid instrument for measuring psychological constructs such as personality or aptitude.

Case study

In-depth investigation of a single individual, group or event, often using multiple data sources over time.

Overt observation

Observation in which participants know they are being watched.

Covert observation

Observation conducted without participants’ awareness to reduce demand characteristics.

Participant observation

Observation where the researcher actively takes part in the group being studied.

Non-participant observation

Observation where the researcher remains separate from the participants being observed.

Behavioural checklist

Pre-set list of operationally defined behaviours to be recorded during structured observations.

Time sampling

Observational technique recording behaviour at fixed intervals (e.g., every 5 seconds).

Longitudinal study

Research that follows the same participants over an extended period to observe changes.

Quantitative data

Numerical information that can be statistically analysed.

Qualitative data

Descriptive, non-numerical information providing rich detail about experiences or opinions.

Objective data

Information collected without personal bias, often via instruments or strict criteria.

Subjective data

Information influenced by personal opinions, feelings or interpretations.

Mean

Arithmetic average of a data set, found by dividing the total of scores by the number of scores.

Median

Middle value in an ordered data set; average of the two middle scores when N is even.

Mode

Most frequently occurring value in a data set; a distribution may be bimodal or multimodal.

Range

Measure of dispersion calculated by subtracting the lowest score from the highest.

Standard deviation

Statistic showing the average distance of each score from the mean; greater SD indicates more variability.

Scatter graph

Plot that displays the relationship between two quantitative variables in a correlational study.

Bar chart

Graph using discrete bars to represent the magnitude of categories, suitable for mean scores of groups.

Histogram

Graph showing frequency distribution of continuous data with adjacent bars of equal width.

Ecological validity

Extent to which findings can be generalised to real-life settings outside the study.

Internal validity

Degree to which observed effects are due to the manipulation of the IV and not confounding variables.

External validity

Extent to which study results can be generalised to other people, places or times.

Inter-rater reliability

Level of agreement between two or more independent observers recording the same behaviour.

Test-retest reliability

Consistency of a measure when the same test is administered to the same participants on two occasions.

Split-half reliability

Assessing internal consistency by correlating scores from two halves of the same test.

Social learning theory

Theory that new behaviours are acquired by observing and imitating others, especially role models.

Operant conditioning

Learning process where behaviour is shaped by consequences such as reinforcement or punishment.

Positive reinforcement

Adding a pleasant stimulus after a behaviour to increase its likelihood.

Negative reinforcement

Removing an unpleasant stimulus after a behaviour to increase its likelihood.

Punishment

Applying an unpleasant stimulus or removing a pleasant one to decrease a behaviour’s frequency.

Bystander apathy

Reluctance to help someone in need when others are present, linked to reduced personal responsibility.

Diffusion of responsibility

Tendency for individuals to feel less personally responsible for action when others are present.

Personal space

Invisible boundary surrounding a person, intrusions into which can cause discomfort or threat.

Oxytocin

Hormone associated with social bonding and modulation of interpersonal distance preferences.

Empathy

Capacity to understand (cognitive) and share (affective) another person’s emotional state.