Many memory theories have proposed that there are multiple stages of memory, but psychologists Atkinson and Shiffrin (1968) came up with an explanation of memory called "the multistore model", which states that there are three stores of memory called the sensory memory, the short-term memory and the long term memory. This came about due to the information-processing system, which is defined as a flow of information through a system. Each store has a different capacity, each longer than its predecessor. The sensory memory can store information for very brief periods of time, before it is either forgotten or passed on to the short-term memory, where it is encoded according to sound. The STM has a capacity of 7+/- 2 pieces of information, and can store information for a short period of time, and, if not rehearsed, can be forgotten within the space of about 30 seconds. If it is not forgotten, it is passed on to the long-term memory, where it can be stored for a lifetime, but can be lost due to decay or interference. The main strengths of this theory are that it is a simple idea, which is believable, and it also distinguishes between the long-term and short-term memory stores. This suggests the long and short-term memory stores work differently in terms of capacity, duration and encoding. This has come from studies of brain-damaged people who have subsequent memory impairment. Some of the main criticisms of this system are that it is too simple, and does not take factors into account such as memory strategies. Also, it defines an amount of information that can be stored, rather than stating the nature of this information. It doesn't explain how things can be remembered which were funny, or important, or traumatic for example, it merely states that a certain amount or information can be stored in the mind. Also, it doesn't explain the processes involved in transference of information from one store to the next, it only states that the information moves from one store to another, rather than stating how it does this.
