 We can illustrate this problem with an example. Suppose we have a subject who is presented, at one time, with a red tomato and a green apple. This visual input is, Treisman says, initially broken up for specialized distributed processing—so that, for example, one part of the brain is responsible for detecting the shapes of things, a different part is responsible for detecting their colours. The shape-detecting centres represent the fact that a tomato-shaped thing is present, and they represent the fact that an apple-shaped thing is present. The colour-detecting centres represent the fact that a red thing is present, and the fact that a green thing is present. But the subject, if he is a normal human, knows more than is implied by these four facts: He knows that the red thing is the tomato-shaped thing and the green thing the apple-shaped thing. To know this he must have a way of ‘binding’ the representation of red in the colour centre with the representation of the tomato shape in the shape centre. The binding problem is the problem of knowing how to put together the properties that have been detected in separate specialized detection centres.