Priming can occur following perceptual, semantic, or conceptual stimulus repetition. For example, if a person reads a list of words including the word table, and is later asked to complete a word starting with tab, the probability that he or she will answer table is greater than if they are not primed. Another example is if people see an incomplete sketch they are unable to identify and they are shown more of the sketch until they recognize the picture, later they will identify the sketch at an earlier stage than was possible for them the first time. The terms positive and negative priming refer to when priming affects the speed of processing. Negative priming is more difficult to explain. The difference between perceptual and conceptual primes is whether items with a similar form or items with a similar meaning are primed. Perceptual priming is based on the form of the stimulus and is enhanced by the match between the early and later stimuli.
• Cognitive Psychology