Psychology key terms

A chemical messenger that carries signals between nerve cells.

An observation in which the researcher watches people without taking part in their activities.

Sending and receiving messages without using words.

A symmetrical, bell-shaped distribution in which most scores cluster around the centre and the mean, median and mode are equal.

An influence that encourages a person towards involvement in an activity.

A testable statement predicting no difference between conditions or no relationship between variables.

The top number in a fraction, showing how many parts are being considered.

The influence of learning, experience and the environment on behaviour.

Following a direct order from someone perceived to have authority.

Understanding that an object continues to exist even when it cannot be seen.

Watching another person’s behaviour and its consequences.

A research method that collects data by watching and recording behaviour.

An influence of an observer’s expectations or personal inclinations on which behaviours they choose to observe and how they record or interpret them.

A change in participants’ behaviour because they know an observer is present.

A monocular depth cue in which an object that partly hides another is perceived as nearer than the object it hides.

Records collected and published by government agencies. Police-recorded crime statistics count offences reported to or detected by the police and recorded by them.

An arrangement in which each object in one group is paired with exactly one object in another group.

The beginning of a condition or its symptoms; this may occur before a formal diagnosis.

A body position with arms not folded across the body and legs not crossed; it may indicate relaxation, confidence or agreement.

A question that allows someone to answer freely in their own words.

Learning through the consequences of behaviour: reinforcement makes behaviour more likely, while punishment makes it less likely.

Defining a variable precisely in terms of how it is manipulated or measured in a study.

Selecting people who are conveniently available and willing to take part.

The pattern of light reaching the eyes from the environment, containing information about objects and surfaces.

A change in performance caused by the sequence in which conditions are completed, such as practice, fatigue or boredom.

Changes in performance caused by completing conditions in a particular sequence, such as improvement through practice or deterioration through fatigue.

A score unusually far from the other scores in a dataset.