Priming is a phenomenon in which exposure to one stimulus influences how a person responds to a subsequent, related stimulus. These stimuli are often conceptually related words or images.
Priming effects appear in a person’s responses to stimuli, such as the speed with which the person is able to categorize a string of letters as a word or non-word. For example, a moment after a person sees the word doctor, she will be faster to recognize the word nurse than she will be to recognize an unrelated word (like cat) because the medical concepts are closely associated in her mind.
The priming process is theorized to occur when mental representations of concepts are activated by a person's exposure to something that those concepts are related to. This activation influences how the person responds to the concepts—such as by making the response quicker. Some scientists have described priming effects as a sort of rational bias, where the mind interprets ambiguous new perceptual information in a way that is consistent with information it has recently perceived.
Priming effects are thought to be based on an activation of concepts and relationships between them that are stored in a person’s long-term memory. These associations—between dog and cat, for example—are learned over time and tapped when priming occurs.
Semantic priming describes the improved processing of a stimulus after exposure to one that has a related meaning. Encountering a stimulus at one time can also make it easier for a person to process the same stimulus shortly thereafter, an effect called repetition priming.
Subliminal priming is the use of stimuli to influence a person’s cognitive processing without that person being aware of the prompts. For example, as part of an experiment, an image may be flashed on a screen so rapidly that a person does not consciously notice it. Supraliminal priming uses a stimulus that a person can consciously perceive.
Helpful priming effects may occur in everyday life, such as when one or more words in a sentence help a reader or listener to more easily interpret a related word that has multiple possible meanings. While there is controversy around the subject of “social priming"—which includes priming that is purported to influence attitudes and observable behavior such as walking speed—priming effects related to perception and information processing have been robustly demonstrated.
Priming research is used to explore the workings of memory, perceptual processing, and how subtle cues affect people’s thinking. In a more general sense, the term “prime” can describe a stimulus used to influence participants’ thinking in some measurable way as part of any psychological experiment.
Priming effects offer insight into how the brain stores information in memory and how it uses that information. They suggest that the brain is adapted to more readily process certain kinds of information after being exposed to something related. Researchers have also explored the capacity of primes to incite emotional or behavioral changes, though such effects are less well-established.
Some psychologists have argued that priming can have surprising effects on our behavior: that seeing an image of money can affect our political views, for instance, or reading words associated with the elderly can make people move more slowly. Follow-up tests of a number of these “social priming” effects have cast doubt on whether they are genuine.