The multi-store model
Atkinson and Shiffrin (1968) proposed a theoretical framework of memory known as the multi-store model (MSM). The MSM consists of three unitary stores: the sensory register (SR), short-term memory (STM), and long-term memory (LTM). According to Atkinson and Shiffrin, information is passed from one store to the next in a linear way.
Each store has its own characteristics in terms of coding, capacity, and duration.
Coding refers to the way in which information is stored and processed in a memory store.
Capacity refers to the amount or quantity of information held in a memory store.
Duration refers to the length of time information is held within a memory store.
According to the MSM, information from the outside world enters the sensory register (SR) through the senses. The SR consists of separate modality-specific stores, including the iconic store for visual information, the echoic store for auditory information, and the haptic store for touch. It has a very large capacity but a brief duration: iconic memories last approximately 50 milliseconds to 2 seconds, whereas echoic memories may last for a few seconds. Information that receives attention passes to STM. If information is not attended to, it is rapidly lost through trace decay or displacement. Displacement may also occur when new sensory information replaces existing information in the sensory register.
STM mainly codes information acoustically. It has a limited capacity of approximately 7 ± 2 items, although chunking can increase the amount of information held, and a duration of approximately 18–30 seconds. Maintenance rehearsal keeps information in STM for longer. Information that receives sufficient rehearsal is transferred from STM to LTM.
LTM mainly codes information semantically. It has a potentially unlimited capacity and a duration of up to a lifetime. Through retrieval, information is transferred from LTM to STM, where it can be consciously used.