An attempt is made to explain the geometric illusions by assuming that ‘visual’ space is non‐Euclidean, and that the departure from Euclidean geometry is the result of the interaction between the elements within the ‘visual’ space. The interaction is represented by a metric equation, and, by assuming that the subjective judgements are made on the basis of a context‐dependent geometry given by the metric equation, explicit expressions for some of the well‐known illusions are derived. Experimental data are presented and reviewed to evaluate the validity of th