priming

n.

1. The act of one that primes.
2. The explosive used to ignite a charge.
3. A preliminary coat of paint or size applied to a surface.

n. 1. another term for primer.

2. gunpowder placed in the pan of a firearm to ignite a charge.

See the Introduction, Abbreviations and Pronunciation for further details.

The application of a primer.

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In reacting to an object or stimulus we often benefit from previous exposure to the same or a related object. It is easier to identify a face, for instance, when that face has been encountered in the recent past. Such benefits in their various forms are referred to as manifestations of priming. The major distinction is between cases in which the same event is repeated (repetition priming) and ones in which benefits are induced by a different but related object or stimulus (e.g. semantic priming, phonological priming).

Repetition priming was first discovered in the context of measurements of the threshold for identifying visually presented words. If a word has been read a few minutes previously its threshold is markedly lowered. Hence repetition priming is a memory phenomenon whereby an initial encounter with an object leaves behind some influence on later performance. It is now known that priming effects can last for very long periods of time. It has been shown, for example, that a passage of typographically inverted text will be read faster if reading similarly inverted text was practised a year earlier, and moreover that this benefit is greatest when the same passage is repeated. Thus memory under these conditions seems to maintain a record of a far remote episode in which a particular passage was read in an unusual (inverted) type. Parallel results have been observed with other materials such as faces and pictures. When a person studies a picture on two separate occasions separated by several days, the pattern of their eye movements is characteristically different on the second compared to the first occasion.

Priming is detected even when the earlier exposure is not recollected. This observation suggests that priming and explicit recollection are distinct processes and there is indeed much evidence in support of this proposal. Numerous variables affect priming and explicit memory (e.g. recall, recognition) differently. As an example, depth of processing (thinking about an object's meaning versus making judgements about its perceptual qualities) has a substantial effect on measures of explicit memory but little effect on priming, whereas changes in modality between study and test have a substantial impact on priming but little effect on explicit memory. Even more striking is the fact that amnesic individuals whose ability to recall prior events is impaired may often show entirely normal levels of priming. This has suggested to some that different neural structures mediate priming and episodic memory, and consistent with this is the fact that brain-imaging and lesion studies have localized them to different brain systems: while episodic memory depends crucially on the medial temporal lobes, (visual) priming is often associated with more posterior sites such as the fusiform gyrus. However, there exists some controversy over whether distinct computational mechanisms are required to account for priming and other types of memory or whether they instead emerge from a unitary memory system which can be probed in different ways (see Schooler, Shiffrin, and Raaijmakers 2001).

What is the basis of the enduring influence of repetition in a priming task? One idea is that priming is simply the temporary activation of existing mental representations (e.g. word nodes) but the fact that priming can last over periods of months or even years and that it can occur for novel stimuli argues against such an explanation. More plausible is the notion that the initial presentation of a stimulus is encoded in long-term memory, for instance as a set of tiny weight changes in the connections in a distributed system, and that these changes can influence later processing of the same stimulus in a small but none the less detectable way. Brain-imaging and electrophysiological studies have revealed a phenomenon called repetition suppression whereby the second occurrence of a stimulus evokes less brain activation than the first. This suppression, which is especially marked for familiar as opposed to unfamiliar stimuli, appears to be the functional basis of priming and is consistent with an enduring facilitation in processing a stimulus as a result of long-term learning.

In contrast to repetition priming, which can be very long-lasting, semantic priming is usually much more short-lived. In a typical procedure, a person reads a pair of words such as rake–leaf which appear in succession with a brief interval between them. The first word does not require any response but the second requires a lexical decision (i.e. is it a word or a non-word?) or has to be named. Numerous experiments have shown that such decisions are speeded up if the first, prime, word is semantically related to the second, target, word. However this form of priming is disrupted or even abolished when the interval between the words is longer than one or two seconds or if other events intervene. Semantic priming can be observed when the prime–target interval is very brief (e.g. 250 milliseconds), suggesting that the effect can be automatic and outside voluntary control. When the interval is longer (e.g. 500 milliseconds) patterns of priming effects are somewhat different from those observed at shorter intervals and suggest a role for a second mechanism based on conscious expectancies.

Semantic priming has been used extensively as a means of drawing inferences about the way in which semantic and conceptual knowledge is organized. For example, it has been used to monitor the longitudinal loss of semantic knowledge in people developing dementia. Much of this work is driven by the assumption that semantic priming is attributable to the automatic spreading of activation between concepts, but this view has been questioned. There is little direct evidence of spreading activation. More recent models have viewed semantic priming, like repetition priming, as being based on long-term learning.

Both semantic and repetition priming appear to occur subliminally, that is, when the initial event is too brief to be consciously perceived, although few issues in experimental psychology have proven so controversial. In one example, Dehaene et al. (1998) flashed number words (e.g. six) very briefly prior to digits (e.g. 3) and participants were simply asked to decide whether the digit was greater or less than 5. Dehaene et al. found that these decisions were speeded if the number word fell on the same side of 5 as the digit and were slowed if it fell on the opposite side, even when the number word prime was not consciously visible. The neural basis of this unconscious priming effect was in the motor cortex, suggesting that the prime activated a motor response which could either facilitate or inhibit responding to the digit depending on whether it fell on the same side of 5 or not. Hence the subliminal prime triggered essentially the same stream of perceptual, semantic, and motor processes as a consciously perceived stimulus.

(Published 2004)

— David Shank

Bibliography
• Dehaene, S., et al. (1998). 'Imaging unconscious semantic priming'. Nature, 395.
• Schooler, L. J., Shiffrin, R. M., and Raaijmakers, J. G. W. (2001). 'A Bayesian model for implicit effects in perceptual identification'. Psychological Review, 108.

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Dansk (Danish)
n. - tændladning, grunding, overkog, plukning

Nederlands (Dutch)
voorbereiding, ontstekings- materiaal

Français (French)
n. - (Constr) application d'un apprêt, (Mil) amorçage

Deutsch (German)
n. - Vorbereitung, Grundierung

Ελληνική (Greek)
n. - (επίστρωση με) αστάρι, αστάρωμα, γέμιση, γόμωση, θρυαλλίδα

Italiano (Italian)
innesco

Português (Portuguese)
n. - escorva (f), primeira demão (f)

Русский (Russian)
заправка, заливка

Español (Spanish)
n. - imprimación, apresto, primera mano

Svenska (Swedish)
n. - flödande, tändsats, grund(nings) färg

中文（简体）(Chinese (Simplified))
装雷管, 起爆剂, 装点火药

中文（繁體）(Chinese (Traditional))
n. - 裝雷管, 起爆劑, 裝點火藥

한국어 (Korean)
n. - 뇌관을 달기, 점화약

日本語 (Japanese)
n. - 雷管取付け, 点火薬, 呼び水, 下塗り, 水気立ち, 急速な詰め込み

العربيه (Arabic)
‏(الاسم) مص, فتيل, شعله, الطبقه الأولى او التحضيريه من الدهان‏

עברית (Hebrew)
n. - ‮תמיסת סוכר המוספת לבירה, צבע-יסוד, אבקת-שרפה הנתחבת לרובה מיושן, הכשרה, שינון‬

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