Procedural memory refers to the skills that humans possess. Tying shoelaces, riding a bicycle, swimming, and hitting a baseball are examples of procedural memory. Procedural memory is often contrasted with episodic and semantic memory. Episodic and semantic memory are both classified as types of declarative memory because people can consciously recall facts, events, and experiences and then verbally declare or describe their recollections. In contrast, nondeclarative, or procedural, memory is expressed through performance and typically does not require a conscious effort to recall.
Could you learn how to tie your shoelaces or to swim through purely declarative means say, by reading or listening to descriptions of how to do it? If it would be possible at all, the process would be slow, difficult, and unnatural. People best gain procedural knowledge by practicing the procedures directly, not via instructions given in words. Verbal coaching in sports is partly a case of trying to impart procedural knowledge through declarative means, although coaching by example (and videotape) may work better. Still, in most cases there is no substitution for practice. Procedural learning may take considerable effort, and improvements can occur over a long period of time. The accompanying chart, entitled “Practice and Speed in Cigar-Making,” shows the effect of practice on Cuban factory workers making cigars. The performance of the workers continued to improve even after they had produced more than 100,000 cigars.
Interaction of Long-Term Memory Systems
Although long-term episodic, semantic, and procedural memory all represent independent systems, it would usually be wrong to think of a particular task as relying exclusively on one type. The examples used above (remembering yesterday’s events, knowing that Thomas Jefferson was president, or tying shoes) represent relatively pure cases. However, most human activities rely on the interaction of long-term memory systems. Consider the expression of social skills or, more specifically, table manners. If you know to set the dinner table with the fork to the left of each plate, is this an example of procedural memory, semantic memory, or even episodic memory from having witnessed a past example? Probably the answer is some blend of all three. In addition, procedural memory does not apply only to physical skills, as in the previous examples. Complex cognitive behavior, such as reading or remembering, also has a procedural component the mental procedures we execute to perform these activities. Thus, the separation of procedural and declarative memory from one another is not clear-cut in all cases.