Sensory memory, which should not be confused with perceptual memory, is in effect a very short STM store that corresponds approximately to the moment when an item is perceived. STM is a memory system for holding a limited memory for periods up to about 20 to 30 seconds (but that can be renewed if information within in is rehearsed), and which is essential for language comprehension. LTM, sometimes referred to as secondary or permanent memory, is memory consisting of information that is stored for periods of about 30 seconds up to decades, and which is often broken down into episodic and semantic memory.
See Alzheimer’s disease, Corsi block-tapping task, Declarative (or explicit) and procedural memory, Entorhinal cortex, Episodic event and semantic memory, Memory, Mobile conjugate reinforcement, Operant train task, Perceptual memory, Phonological loop, Primacy effect, Recency effect, Working memory.