Where does selectivity collide?

The tendency of an audience to seek out and attend to messages that agree with what they already believe, and to avoid those that challenge it. Lazarsfeld, Berelson, and Gaudet's 1944 The People's Choice found that voters attended mostly to campaign material that fit their existing leanings, and Sears and Freedman's 1967 review Selective exposure to information weighed the evidence for and against a general preference for agreeable content. Here the referent is a pattern in how people choose what to read or watch, observed across audiences, and it is not a reaction favoring one product, a neuron favoring one stimulus, or a database predicate that returns few rows.[1][2]

Unit

One person's choosing to attend to agreeable content and skip discordant content

Recovery means

Not applicable

Measured by

Assessed by tracking which messages people choose in exposure experiments and by media diaries or self-report

A single neuron's tendency to fire strongly for one particular feature of a stimulus and weakly or not at all for others, such as a bar of light at one orientation. Hubel and Wiesel's 1962 Receptive fields, binocular interaction and functional architecture in the cat's visual cortex recorded cells in the visual cortex that responded best to an edge at a preferred angle, the classic case of orientation selectivity. The referent is a tuning property of nerve cells, read from their firing, and it is not a reaction favoring one product, an audience favoring agreeable messages, or a query predicate's result size.[3]

Unit

One neuron's preferred stimulus feature, read from its firing rate across stimuli

Recovery means

Not applicable

Measured by

Quantified by recording spikes while varying a stimulus feature and fitting a tuning curve or a selectivity index

The degree to which a chemical reaction forms one product in preference to the others that are possible, described as which functional group reacts (chemoselectivity), which position reacts (regioselectivity), or which spatial arrangement forms (stereoselectivity). Hassner's 1968 Regiospecificity. Useful terminology in addition and elimination reactions introduced the position-based vocabulary now standard for naming this preference. The referent is a property of a reaction and its conditions, scaled by product ratios and yields, and it is not a neuron's preferred stimulus, an audience's preferred messages, or the fraction of rows a database predicate returns.[4]

Unit

The ratio of the favored product to competing products from one reaction

Recovery means

Not applicable

Measured by

Reported as product ratios, percent yield of the major product, or an enantiomeric or diastereomeric excess

In query optimization, the fraction of rows in a table that satisfy a given condition, used to estimate how much data an operation will return and thus which plan is cheapest. Selinger and colleagues' 1979 Access path selection in a relational database management system introduced selectivity factors as the estimates a cost-based optimizer uses to choose among access paths and join orders. The referent is a numeric estimate attached to a predicate, between zero and one, and it is not a reaction's product preference, a neuron's stimulus preference, or an audience's preference for agreeable messages.[5]

Unit

A number between 0 and 1: the estimated fraction of rows a predicate keeps

Recovery means

Not applicable

Measured by

Estimated from table statistics such as row counts, distinct values, and histograms, then checked against actual result sizes