The everyday sense of this phrase is found in phonetics and psycholinguistics, where the phenomenon is studied as part of a theory of speech production; also called a slip of the tongue. Such slips seem not to be random; e.g. segments occurring initially in syllables seem to interfere only with other syllable-initial segments. The suggestion is that tongue-slips are not just errors of articulation, but are rather the results of incorrect neural programming (‘slips of the brain’, as some would say). The analysis of these errors motivates hypotheses about the properties of the neurolinguistic control governing speech.