Procedural memory is a memory of skills and procedures. As compared with 
declarative memory, it is governed by different mechanisms and different brain circuits. An example of procedural learning is learning to ride a bike, learning to touch-type, learning to swim, etc. There is no simple stimulus-response pairing. Instead, the brain is trying to figure out optimum memory pattern by trial and error. Procedural memory can be very durable.
 
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