Conceptual blending (or conceptual integration) is a means of describing the cognitive processes involved in understanding meaning in language. In particular, it argues that large areas of meaning results from the motivated integration of information from separate mental structures to form a new structure, a blend, which combines selective information from those structures into a new, emergent, mental space.
For example, a sentence such as If Queen Victoria had the atom bomb, she would use it against the French is a counterfactual, whose comprehension is not easily explained in traditional semantics. Conceptual blending argues that the two sets of mental information (the atomic bomb and the relationship between Victorian Britain and France) are projected into a blend which contains combined information about the military power of the atomic bomb and the Victorian approach to Empire, and this blended mental space is then subconsciously 'simulated' under its own rules. In this way, a reader can understand what the counterfactual means using more information than what is originally supplied by the mind - the reader only knows disparate facts about Victoria and the atom bomb, whereas the blend contains gestalt information which is greater than its parts.