Memory allows us to encode, store, and recall information and experiences. It involves three basic memory systems according to Atkinson and Shiffrin: sensory memory, short-term memory, and long-term memory. Sensory memory briefly stores sensory information for under a second. Information may then be transferred to short-term memory, which can hold a small amount of information for under 20 seconds, acting as a scratch pad. This allows us to process and remember information as we use it.