Priming is an implicit memory effect in which exposure to one stimulus influences the response to another stimulus. Experiments in the early 1970s showed that people were faster recognising a word, when the word followed a related word. For example, NURSE is recognized more quickly following DOCTOR than following BREAD. Activation spreading among related ideas was the best explanation for this effect. In experiments the same target stimuli can be presented with different primes. This allows the priming effect to be measured.