The three-stage theory, developed by Atkinson and Shiffrin, states that a memory must pass through two distinctly different memory systems if it is to make it to long-term storage. The process begins in sensory memory (box one), where sensory stimuli provide information that is lost within a second or two unless it is deemed very important. It then moves to short-term memory (box two), where unrehearsed information is lost in about 15 to 30 seconds. In short-term memory, information can be consolidated through maintenance rehearsal and moved to long-term memory (box three), where it can be retained indefinitely.