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Priming is the way one stimulus pre-warms the brain for the next: flash the word doctor and the word nurse is recognized a few milliseconds faster than the word bread. The explanation is spreading activation, in which the brain stores concepts in an associative web and activation flows from one node to its neighbors. Researchers distinguish semantic priming, as when dog primes wolf, from associative priming, as when the phrase raining cats and dogs links dog to cat. Negative priming does the opposite, slowing responses to information the brain has tagged to ignore. Subliminal priming, studied by flashing words for under 80 milliseconds behind a visual mask, can bias motor responses but fades after about 500 milliseconds. Conscious cues last longer: bicultural participants in Hong Kong shown American symbols described a lone cartoon fish as a leader, while those shown Chinese symbols saw it as chased or rejected.

The field’s later turn was a crisis. Behavioral priming studies of the 1990s and 2000s claimed that words about the elderly made people walk slower and that holding hot coffee made an interviewer seem warmer. From 2012, independent labs could not replicate them. Daniel Kahneman called priming a poster child for doubts about psychological research and by 2022 declared behavioral priming effectively dead. Investigators blamed the experimenter effect and publication bias rather than fraud. The firmest evidence now comes from neurology, where patients with severe memory damage still show intact priming.

• John Bargh’s 1996 study primed participants with words like Florida, forgetful and wrinkle, then timed their walk down a hallway.
• A 2008 study claimed a hot drink before an interview made the interviewer seem warmer and an iced one made them seem cold.
• Amnesia patients with medial temporal lobe damage cannot recall a word list but complete word stems like D-E-F at the same rate as healthy people.
• Alzheimer’s patients show impaired conceptual priming but intact visual perceptual priming, a double dissociation.
• Perceptual priming reduces processing in the extrastriate cortex, while conceptual priming reduces blood flow in the left prefrontal cortex.