Where does latent collide?

Francis Bacon, in The Elements of the Common Lawes of England (1630, composed around 1597), drew the classic line between a hidden ambiguity (Latin ambiguitas latens) and one plain on the page (ambiguitas patens): a hidden ambiguity does not show in the words themselves but appears only when they are applied to the outside facts, as when a will leaves property to 'my nephew John' and two nephews bear that name. Bacon allowed outside evidence to resolve the hidden kind, since the words alone cannot settle it, while barring such evidence for the plain kind. The referent is a concealed defect in the meaning of a legal text that surfaces against the facts, and it has nothing to do with heat stored in a change of state, an unobserved statistical quantity, or unrewarded learning in an animal.[1]

Unit

One ambiguity in a document, hidden until the words meet the facts

Recovery means

Not applicable

Measured by

Found by a court when the text, applied to the facts, admits more than one referent, and resolved by admissible outside evidence

Joseph Black, whose Glasgow lectures of the 1760s were published after his death as Lectures on the Elements of Chemistry (1803), named the heat that a substance takes in or gives out while it changes state without any change in temperature, as when ice melts to water at a steady zero degrees. He called it latent, meaning hidden, because a thermometer registers nothing while the heat does its work of breaking or forming the bonds of the solid, liquid, or vapour. The referent is a quantity of thermal energy tied to a change of state, measured in energy per unit mass, and it is unrelated to a hidden flaw in a document, a factor inferred from test scores, or learning an animal does not display.[2]

Unit

Thermal energy per unit mass exchanged in a phase change, for example joules per gram

Recovery means

Released again in the reverse change, as vapour condensing or water freezing

Measured by

Determined by calorimetry from the heat added or removed while the temperature holds constant through the transition

Charles Spearman, in his 1904 paper 'General Intelligence,' Objectively Determined and Measured, inferred a common quantity behind a set of school and sensory test scores that no instrument measures directly, the unobserved factor he treated as general ability. Bollen's 2002 review Latent Variables in Psychology and the Social Sciences set out the modern treatment, in which a latent variable is a quantity that is not observed but is estimated from the pattern of correlations among the things that are. The referent is a hypothesised, unmeasured quantity standing behind observed indicators, and it is a different thing entirely from a concealed legal ambiguity, hidden heat in a phase change, or learning held back until reward.[3][4]

Unit

One unobserved quantity, scaled by fixing its variance or one of its loadings

Recovery means

Not applicable

Measured by

Estimated from the covariances among observed indicators by factor analysis or structural equation modelling

Edward Tolman and Charles Honzik, in their 1930 study Introduction and Removal of Reward, and Maze Performance in Rats, showed that rats allowed to wander an unrewarded maze learned its layout without acting on it, then ran it almost error-free as soon as food was introduced, so the learning had been present but unshown. Tolman's 1948 Cognitive Maps in Rats and Men developed this into the claim that animals build an internal map that guides behaviour only when there is reason to use it. The referent is knowledge gained without reinforcement that stays hidden in behaviour until an incentive draws it out, and it bears no relation to a hidden ambiguity in a text, heat absorbed in melting, or an unobserved statistical factor.[5][6]

Unit

Knowledge of a task acquired without reward, per animal

Recovery means

Not applicable

Measured by

Inferred from a sudden drop in errors or running time once reward is introduced, compared against a consistently rewarded group