What Causality Means in Psychology
Causality is one of the central concepts in psychological research. Establishing that one thing causes another is harder than it sounds, and most of the debates in psychology about research quality come back to this single issue.
A relationship in which one variable directly produces a change in another. A change in the independent variable (IV) leads to a measurable change in the dependent variable (DV).
A statistical relationship between two variables such that when one changes, the other tends to change in a predictable direction. This says nothing about which variable, if either, is driving the other.
The distinction matters because psychology frequently studies variables that move together without one causing the other. Confusing the two leads to bad conclusions, and bad conclusions lead to bad interventions.
A correlation between two variables never, on its own, tell you that one causes the other. This is not a technicality: it is a genuine limit on what the data can show. Always ask what a correlational finding can and cannot establish.