Where does slip collide?

A slip of the tongue is an unintended error in producing speech, such as swapping sounds or exchanging words, that linguists study for what it reveals about how a speaker assembles an utterance. Meringer and Mayer's 1895 Versprechen und Verlesen gathered and classified thousands of such errors as evidence of the ordinary units and stages of speech planning, and Fromkin's 1971 The non-anomalous nature of anomalous utterances showed that they follow regular patterns that expose sounds, syllables, and words as real planning units. In this meaning the slip is a lawful production error read as a window on the language system, not a hidden wish behind the error, a shift of crystal planes in a metal, or the offset of rock across a fracture.[1][2]

Unit

A single unintended speech error, classified by the linguistic unit affected

Recovery means

The speaker often detects and repairs the error in the words that follow

Measured by

Collected in error corpora and elicited in the laboratory, then coded by type such as sound exchange or word substitution

Crystallographic slip is the way a crystal deforms permanently: whole planes of atoms glide over one another along preferred directions once the applied stress is high enough, leaving visible step lines on a polished surface. Ewing and Rosenhain's 1900 The crystalline structure of metals reported these slip bands on strained metal grains, and Taylor's 1934 The mechanism of plastic deformation of crystals explained them through the motion of line defects called dislocations that let the planes shear one at a time rather than all at once. Here the slip is an atomic-scale gliding of lattice planes measured as shear strain, not a spoken error, an unconscious motive, or a large displacement of rock along a geological fault.[3][4]

Unit

One increment of plastic shear as planes glide along a slip system, scaled as shear strain

Recovery means

The slip is permanent, and only the accompanying elastic strain returns when the load is removed

Measured by

Observed as slip bands and slip lines under the microscope and quantified by resolved shear stress and dislocation density

A Freudian slip, or parapraxis, is an everyday error of speech, memory, or action that psychoanalysis reads as the surfacing of a repressed wish or intention. Freud's 1901 Zur Psychopathologie des Alltagslebens (The Psychopathology of Everyday Life) argued that such lapses are not random but are motivated by unconscious content that breaks through the words the speaker meant to say. In this meaning the slip is a meaningful error interpreted as evidence of a hidden mental cause, which sets it apart from the linguist's slip studied as a neutral production error, and from the physical meanings of gliding crystal planes or displaced rock.[5]

Unit

A single lapse of speech, memory, or action treated as one parapraxis

Recovery means

Not applicable

Measured by

Identified case by case in clinical interpretation, and studied experimentally by inducing and counting speech errors

In geology, slip is the relative displacement of the two sides of a fault, measured as the distance and direction one block has moved past the other along the fracture. Reid, Davis, Lawson, and Ransome's 1913 Report of the committee on the nomenclature of faults fixed the technical vocabulary, defining net slip and its components such as strike slip and dip slip so that offset could be described consistently. Here the slip is a measured offset of rock masses across a crustal break, ranging from millimetres to kilometres, and it has nothing in common with a spoken error, an unconscious motive, or the atomic gliding of planes inside a single crystal.[6]

Unit

The offset of one fault block relative to the other, in metres of displacement

Recovery means

Not applicable

Measured by

Estimated from displaced markers in the field, from trenching, and from geodetic surveys such as GPS and radar