The Atkinson-Shiffrin Model proposes that memory consists of three memory stores: sensory memory , short-term memory , and long-term memory . This is one of the first models developed to represent memory and was first proposed in the 1960's.
Sensory memory is looked at in relation to iconic (visual) and echoic (auditory) memory. Atkinson-Shiffrin proposed that when information is transferred to short-term memory it is encoded acoustically, or by its sound. It is by rehearsal that information is passed from short-term memory to long-term memory. Many argue that this model of memory is far too simple to accurately represent the complicated memory process.
From the sensory memory, the material is then passed on to short-term memory. Verbal information in the short-term memory is encoded acoustically , in terms of its sounds. Memories in short-term memory are fragile - although not as fragile as those in sensory memory - and they can be lost from memory within about 30 seconds, unless they are repeated. Only material that has been rehearsed passes from short-term memory to long-term memory. Long-term memory is encoded semantically , in terms of its meaning. Memories in long-term memory are relatively permanent, and they are not likely to be lost. Information in the long-term memory can pass back into short-term memory when we want to actively work with that information again.
One important control process strategy for memory is that of rehearsal, the repetition of information. This control process will make sure that information in the short-term memory can be remembered, and flow onto the long-term memory.