Source: Laboratory of Jonathan Flombaum—Johns Hopkins University

Colloquially, the terms learning and memory encompass a broad range of behaviors and mental systems, everything from learning to tie a shoe to mastering calculus (and a lot in between). Experimental psychologists have divided up learning mechanisms into groups that seem to have different properties, and that seem to rely on different brain systems. A major division is between declarative and non-declarative memory, roughly, the sorts of things a person can express verbally—explicitly, like a birthdate, or what one ate for lunch—and things they cannot quite put into words—things they know implicitly, like how to get home despite not knowing the street names, or how to flip an omelet.

In the domain of non-declarative memory, a crucial kind of learning involves motor learning, sometimes also called procedural memory. Learning to drive a car is a good example. At first it is usually arduous and seems to involve explicit attempts to remember what to do next. Eventually it becomes second nature, though, something that a person just kind of knows how to do—and does better and better with time—but that can be hard to explain to someone else.

Mirror drawing is a common laboratory paradigm for investigating the acquisition of learned motor skills, the kind involved in driving, for example. This video demonstrates standard procedures for mirror drawing.