The multi-storage memory model proposed by Atkinson and Schiffrin provides for three information stores: 1) a sensory register, 2) a short-term storage (STS), and 3) long-term storage (LTS). An incoming stimulus is directly registered in the corresponding sensory modality and either lost or passed on for processing. When Atkinson and Shiffrin developed their model, the other sensory modality systems were not as well understood today (although they still hold many secrets). Still, the model makes room for them in anticipation of future research that will reveal as yet unknown properties. Schiffrin suggests that automatic processing begins the moment a stimulus is presented. Each stimulus, going through successive processing stages, is automatically encoded and activates a series of operations inherent in that process. For example, when an observer perceives a letter, they may automatically encode its contrast, color, and position; then its curves and angles; then as a consonant, and finally its meaning.
Long-term storage stores information permanently, short-term storage for no more than 30 seconds (no repetition), and a sensor register (SR) for a few hundred milliseconds. Atkinson and Shiffrin introduced an essential distinction between the concept of memory and memory stores (Humphreys et al., 2020). They defined the term “memory” as the data to be stored and the term “storage” as the structural element in which this data is stored. Simply stating how long an element is stored does not mean determining precisely wherein the memory structure it is located. Thus, according to their system, information may be admitted to the LTS shortly after it is presented, or it may be held in it for several minutes but never enter the LTS.
Short-term storage is viewed as a working system in which the input information fades and disappears quickly, but not as quickly as from a sensor register. An example of a short-term storage operation is a situation in which a person needs to memorize a short 4-digit code. The capacity of this storage is enough to contain this relatively small amount of information (Humphreys et al., 2020). Nevertheless, in situations when one needs to memorize an 11-digit telephone number, the short-term memory may not work because its capacity will be insufficient.
It is important to note that the form of information representation in the STS may differ from the original sensory form (e.g., a word presented visually may be represented in auditory code). The information contained in the third system, i.e., in the long-term storage, was considered by the authors to be relatively constant, even though it may be inaccessible due to interference with the input information. The function of the is to track the stimuli in the input register (to control the stimuli coming into the LTS) and to provide a place to store the information coming from the LTS.
The way information is forgotten is different for each type of memory. Information in sensory memory decays very quickly. Information in short-term memory is displaced by new incoming information, and information in long-term memory is forgotten because of interference with other related information. According to Atkinson and Schiffrin, one of the most important differences between short-term memory and long-term memory is the mechanism of forgetting. Forgetting, which occurs in short-term memory, occurs because of distraction from the information stored in memory and because of interference with other incoming information.
In the original system, information attenuation in the STS was difficult to pinpoint, but Atkinson and Schiffrin believed it occurred within 15 to 30 seconds. However, if an item is placed in a “repetition buffer,” it can be maintained longer, and the longer it is held there, the more likely it is to be transferred to long-term storage and, according to probability theory, the more likely it is to be displaced from that buffer by new input information.
The person himself mainly controls the transition of information from one storage to another. The information briefly held in the sensory register is scanned, and the selected part of it is entered into the STS. The authors of the model believe that the process of information transfer from the STS can last as long as it is held here. Atkinson and Shiffrin postulated that information could directly enter the sensor register’s long-term storage.
Reference
Humphreys, M. S., Tehan, G., Baumann, O., & Loft, S. (2020). Explaining short-term memory phenomena with an integrated episodic/semantic framework of long-term memory.Cognitive Psychology, 123, 101346.