Priming

Priming is a memory effect whereby exposure to a certain stimulus changes the speed at which a certain memory is recalled or another stimulus is attended to or recognized. Priming works on an implicit level and is involved in a number of cognitive biases such as confirmation bias and the availability heuristic. A simple example is the familiar "red car" phenomenon where a person who buys a red car suddenly starts seeing red cars everywhere. The familiarity of the red car primes them to spot other red cars faster.

Positive vs. negative priming
There are two broad types of priming: Positive and negative. Positive priming involves exposure to a stimulus that speeds up recall or response time, while negative priming slows it down. The most basic form of positive priming is repetition priming, which rather obviously involves the repetition of a stimulus causing recall or recognition of that stimulus to speed up. Negative priming can involve the inhibition of selective attention or the stimulus being associated with being ignored in the past. These priming effects are often modeled on Bayesian principles.

Other types of priming

 * Associative priming: Two stimuli are unrelated, but due to their common appearance together, one will prime the other. Think of Pavlov's dog.
 * Semantic priming: One stimulus primes another in the same conceptual category. For example, the word "cat" may prime the word "lion."
 * Perceptual priming: Priming related to the form of the stimulus. A commonly used task that exemplifies this is word-stem completion, where a stimulus (e.g., "goat") is given and then a word-stem (e.g., "_oat") is to be completed. "Goat" would be favored over "coat" because it was primed.
 * Conceptual priming: Priming related to the meaning of the stimulus. It is similar to (and often enhanced by) semantic priming. For example:
 * ''What mouse walks on two legs?
 * Mickey Mouse!
 * ''What duck walks on two legs?
 * Donald Duck!
 * No, all of them.