Where does exposure collide?

The set of ways a system can be reached by an attacker: its entry and exit points, the channels it listens on, and the data items it accepts. Manadhata and Wing fixed the measurement in 2011 with an attack-surface metric that counts a system's methods, channels, and untrusted data items and weights each by a damage-potential-to-effort ratio, so that two versions of the same software can be compared without knowing any specific vulnerability. The word also survives in MITRE's catalogue name, Common Vulnerabilities and Exposures, where an exposure was originally a configuration or state that is not itself a flaw but gives an attacker a foothold. What distinguishes this meaning is that exposure is a count of reachable surface, and a system can reduce it without fixing a single bug.[1][2]

Unit

A system's interface to untrusted parties, at a given configuration

Recovery means

Attack-surface reduction, fewer entry points, channels, and accepted data items

Measured by

Attack-surface metric along methods, channels, and data; open ports and services; reachable code

The amount a position, portfolio, or insurer stands to lose from a movement in a risk factor. Jorion's textbook made value at risk the standard summary: the loss that will not be exceeded, at a stated confidence level, over a stated horizon. Duffie and Pan's 1997 overview set out the estimation choices (parametric, historical, or simulated) and their limits. Insurers use the older probable maximum loss for the same idea on a single peril, the largest loss a property is likely to suffer from one fire or earthquake. What distinguishes this meaning is that exposure is a monetary quantity conditional on a scenario, and it exists only relative to a factor, a horizon, and a probability.[3][4]

Unit

A position or book, relative to a risk factor over a horizon

Recovery means

Hedging or reinsurance that brings exposure inside a limit

Measured by

Value at risk at a stated confidence and horizon; sensitivities; probable maximum loss

An occasion on which a message reaches a person, whether or not they attend to it. Zajonc showed in 1968 that mere repeated exposure to a stimulus (a nonsense word, a Chinese character, a face) increases liking for it, with no message and no reward; Bornstein's 1989 meta-analysis confirmed the effect across two decades of studies and found it strongest for brief, unrecognised presentations. Krugman argued in 1972 that in advertising three exposures may be enough: the first asks what it is, the second what of it, and the third is a reminder, after which further exposures are repetitions of the third. What distinguishes this meaning is that exposure is counted rather than dosed, its effect is affective rather than physical, and the counting unit (an opportunity to see) is set by the medium.[5][6][7]

Unit

An individual's opportunity to see a message, counted over a campaign

Recovery means

Not applicable, the criterion is liking, recall, or purchase as a function of frequency

Measured by

Reach and frequency; opportunities to see; liking ratings after controlled presentation

The quantity of light energy reaching a unit area of the sensor or film: illuminance times time, in lux-seconds. Jones and Condit surveyed the brightness of exterior scenes in 1941 and derived from it the rule that camera exposure should be set so that the scene's key tones fall at fixed positions on the film's characteristic curve, the empirical basis of the exposure meter. ISO 12232 fixes the modern relation between a sensor's speed rating and the exposure needed for a standard output, and the exposure value EV compresses aperture and shutter time into a single logarithmic number. The reciprocity law says that the same product of illuminance and time gives the same result, and its failure at very long or short times is a named phenomenon. What distinguishes this meaning is that exposure is a physical dose with a unit, and every other field's exposure is a metaphor for it.[8][9]

Unit

A unit area of sensor or film, over the shutter interval

Recovery means

Not applicable, the criterion is a correctly placed tone curve; overexposure and underexposure are the two failure modes

Measured by

Lux-seconds; exposure value; aperture, shutter time, and sensitivity

Any factor whose effect on a health outcome is under study (a chemical, a behaviour, a drug, a social condition) and the contact between a person and it. Rothman, Greenland, and Lash's Modern Epidemiology uses the word for the whole class of putative causes, so that a cohort is compared by exposure status and the measure of effect is a ratio of risks between exposed and unexposed. Lioy argued in 1990 that exposure science needed to be its own discipline: exposure is contact at a boundary, dose is what crosses it, and the two are separated by route, duration, and concentration. What distinguishes this meaning is that exposure is the independent variable of a causal contrast, and its measurement error is a threat to every effect estimate downstream.[10][11]

Unit

A person's contact with an agent, characterised by concentration, route, and duration

Recovery means

Not applicable, the criterion is a valid estimate of the exposure–outcome effect

Measured by

Biomarkers; personal monitors; questionnaires and job-exposure matrices; exposed-versus-unexposed contrasts

Deliberate, repeated confrontation with a feared stimulus or memory under conditions that allow fear to change. Foa and Kozak fixed the mechanism in 1986 as emotional processing: the fear structure must be activated and then met with corrective information, so within-session activation and between-session decline of fear were the markers of a working treatment. Craske and colleagues replaced that account in 2014 with inhibitory learning: exposure teaches a new safety association that competes with the old fear association, so the aim is to maximise expectancy violation and variability rather than to drive fear down within the session. What distinguishes this meaning is that exposure is the treatment, administered on purpose, and the outcome sought is a reduction in the response to the very thing exposed.[12][13]

Unit

A patient, over a course of exposure trials to a feared cue

Recovery means

Fear no longer interferes with function; return of fear is the relapse mode

Measured by

Subjective units of distress; behavioural approach tests; expectancy ratings before and after trials