ABSTRACT
A major theme in studies of both humans and experimental animals is that memory is not a single entity but is composed of several separate systems. The term "nondeclarative" is broader than "procedural," however, and is meant to include all forms of learning and memory that are not declarative such as priming, conditioning, and habituation. Information in declarative memory is initially independent of the hippocampus and related structures. In human amnesia, digit span and other measures of short-term memory are fully intact. This dissociation between short-term and long-term memory can be observed in tests of both verbal and nonverbal materials, including tests of spatial short-term memory. The brain system that supports declarative memory has only a temporary role in the formation of long-term memory. The pertinent data for this conclusion come from studies of retrograde amnesia, which refers to the loss of memories that were acquired prior to the onset of amnesia.
