The Atkinson-Shiffrin model of memory, formulated by psychologists Richard Atkinson and Richard Shiffrin, offers a structured illustration of the human information processing system. First proposed in 1968, the model includes three main components:
Sensory memory: A temporary repository that captures all sensory information, where most of it is lost unless attention is directed to it.
Short-term store: A limited capacity store that can maintain information for a brief period through rehearsal.
Long-term store: Where information which has been rehearsed in the short-term store is held indefinitely.
These components operate in unison to form the foundation of the information processing system as theorized within the scope of human memory and cognitive psychology.
The concept of distinct ways to store memory was far from novel at the time. William James distinguished between primary and secondary memory as early as 1890. His primary memory consisted of concepts kept for a brief time in consciousness, while secondary memory consisted of a permanent, unconscious store.
In addition to the previously proposed primary and secondary memory, Atkinson and Shiffrin proposed a sensory register and a number of control processes that govern memory transfer.
Multi-store Model of Memory
This three-part model of memories is an explanation of how memory processes may function. Alternative frameworks have subsequently been proposed, including procedural reinstatement, a distinctiveness model, and Baddeley and Hitch’s working memory model.
Since its first publication, this model has been closely scrutinized and challenged for a variety of reasons. However, it is recognized for its major impact on subsequent memory research.
Sensory Memory
Sensory registers are the initial repositories where sensory memory is briefly held. These registers capture vast amounts of sensorial information but retain details only momentarily before they decay or are passed on to the short-term store.
This store is commonly referred to as “the sensory register” or “sensory memory,” although it is actually made up of numerous registers, one for each sense. The sensory registers do not analyze the information carried by the stimulus, but rather detect and keep information for milliseconds to seconds for use in short-term memory.
Atkinson and Shiffrin referred to the registers as “buffers” because they keep massive volumes of information from overpowering higher-level cognitive processes. Information is only transferred to short-term memory when it is paid attention to; otherwise, it decays quickly and is forgotten.
Iconic Memory
Iconic memory, perhaps the most researched of the sensory registers, is limited to the visual field. That is, as long as a stimulus enters the field of vision, iconic memory can keep an unlimited quantity of visual information at any given time.
Sensory registers do not allow for further information processing, therefore iconic memory solely stores information about visual stimuli such as shape, size, color, and location. Because higher-level systems have limited capacity, they cannot transfer all information from sensory memory.
It has been hypothesized that the temporary mental freezing of visual data enables the selection of selected components to be passed on for subsequent memory processing. The most significant drawback of iconic memory is the quick decay of the information stored there; objects in iconic memory break down in just 0.5-1.0 seconds.
Echoic Memory
Echoic is another of the sensory registers. The psychologist Ulric Neisser created the term “echoic memory” to describe information stored by the auditory system. Echoic memory, like iconic memory, only stores surface features of sound (e.g., pitch, tempo, or rhythm) and has an almost endless capacity.
Because of the various processes involved, echoic memory storage requires the participation of numerous different brain locations. The majority of the brain regions implicated are in the prefrontal cortex, which houses executive function and is in charge of attentional control. Increased brain activity in the phonological storage and rehearsal system suggests that they are based on the left hemisphere.
Short-term Store
While much of the information in sensory memory fades and is forgotten, some is retained. The information that is attended is transferred to the short-term store (also now known as short-term memory or working memory).
As with sensory memory, information that enters short-term memory decays and is lost; however, information in the short-term store has a longer duration, approximately 18-20 seconds when the information is not actively rehearsed, though this may vary by modality and could be as long as 30 seconds. Fortunately, the information may be stored in the short term for much longer via a technique known as rehearsal, according to Atkinson and Shiffrin.
For auditory information, rehearsal might be interpreted literally as continually repeating the items. However, the phrase can be used to refer to any information that is attended to, such as when a visual image is purposefully retained in the mind.
Information in the short-term memory does not have to be in the same modality as its sensory input. For example, written material that enters visually can be stored as auditory information, and audio input can also be displayed.
The short-term storage capacity is limited to 7 ± 2 pieces of information. These chunks, which Miller identified in his seminal study The Magical Number Seven, Plus or Minus Two, are classified as distinct pieces of information.
Long-term Store
The long-term store (also known as long-term memory) is a virtually persistent storage location. Information saved here can be “copied” and moved to the short-term memory, where it can be accessed and changed.
Information flows from the short-term storage to the long-term store almost automatically. According to Atkinson and Shiffrin, transfer from the short-term store to the long-term store occurs as long as the information is addressed in the short-term store. In this way, varied levels of attention result in varying durations of time in short-term memory.
In this model, as in most memory models, long-term memory is believed to be almost limitless in duration and capacity. Brain structures frequently degrade and fail before any learning limit is reached.
This does not imply that anything stored in long-term memory is always accessible. Rather, it is observed that the links, signals, or associations to the memory degrade; the memory remains intact but inaccessible.
Role of Rehearsal in Memory
Rehearsal is a crucial process in the Atkinson-Shiffrin model of memory, impacting the transition of information from short-term to long-term memory. Two distinct types of rehearsal, maintenance and elaborative, each have different effects on memory retention.
Maintenance Rehearsal
Maintenance rehearsal refers to the repetitive review of information to keep it in short-term memory or to encourage its transfer to long-term memory. It involves a rehearsal loop whereby information is repeated in the same form. Supposedly, the longer an item is retained in short-term memory, the stronger its memory trace in long-term memory.
For example, continuously reciting a phone number to remember it uses maintenance rehearsal. Craik and Watkins (1973) found that the number of rehearsals has no effect on long-term performance for recent items, it is still unclear whether the amount of rehearsal for previous items has an effect on long-term recall.
Elaborative Rehearsal
In contrast, elaborative rehearsal is a deeper processing technique that involves the association of new information with existing knowledge. This method extends beyond simple repetition, requiring individuals to link the new information to other memories or concepts they already understand.
It has been shown to significantly improve the likelihood of transferring information into long-term storage.
Engaging with the content in multiple ways is an effective strategy to promote elaborative rehearsal. For example, discussion or study groups allow you to personalize discrete pieces of information by connecting stories to them and making meaningful links to previously taught concepts.
Influence and Revisions of the Model
The Atkinson-Shiffrin model, also known as the multi-store model or modal model, marked a foundational shift during the cognitive revolution, altering the understanding of human memory structures. Its extensive influence sparked numerous extensions but also attracted critical commentary, leading to various revisions over the years.
Extensions of the Model
Extensions of the Atkinson-Shiffrin model frequently sought to add complexity and depth to the original framework. Notably, researchers expanded upon the model’s simplistic view of memory as a linear process.
For instance, additional types of memory stores — like episodic and procedural memory — were proposed, acknowledging that memory involves a broader, more dynamic network of processes than what was originally conceptualized.
Criticisms
Criticism of the Atkinson-Shiffrin model stemmed from its oversimplification of memory processes. For example, it has been argued that the model does not adequately account for the nuances of human memory, such as the distinctions between semantic and episodic memory.
One of the first and most significant objections leveled at the Atkinson-Shiffrin model was the inclusion of sensory registers as part of memory. Specifically, the original concept appeared to characterize the sensory registers as both a structure and a control mechanism.
According to parsimony, if the sensory registers are control processes, a tri-partite system is unnecessary. Later model modifications addressed these issues by incorporating sensory registers into the short-term store.
Long-term memory is unlikely to store diverse sorts of knowledge in the same way, such as motor abilities for riding a bike, memory for vocabulary, and memory for personal life events. There are distinct variances in how information is kept depending on whether it is episodic (memories of experiences), procedural (knowledge of how to do things), or semantic (generic knowledge).
The model has also been challenged for implying that rehearsal is the primary activity that initiates and supports the transfer of information into LTM. There is minimal evidence to support this notion, and a levels-of-processing framework can predict long-term recollection more accurately. According to this approach, objects encoded at a deeper, more semantic level have greater traces in long-term memory.
Search of Associative Memory
Due to the aforementioned and other criticisms during the 1970s, the original model underwent numerous adjustments to account for phenomena it could not explain. The “search of associative memory” (SAM) model is the pinnacle of such study.
The SAM model employs a two-phase memory system with short and long-term stores. In contrast to the original Atkinson-Shiffrin model, the SAM model lacks a sensory store.
Short-term storage in this model takes the form of a buffer with a restricted capacity. The model assumes a buffer rehearsal system with a size of r. Items enter the short-term store and accompany existing items in the buffer until size r is attained. When the buffer reaches maximum capacity, new items replace an existing item, r.
Memories held in long-term storage are retrieved via a logical process that includes cue assembly, sampling, recovery, and recovery evaluation. According to the model, when an item must be retrieved from memory, the individual gathers the numerous cues for the item in the short-term store.
Using these cues, the individual selects which section of the long-term store to search and then samples any items that correspond to the cues. This search is automatic and unconscious, and would explain how an answer “pops” into one’s mind. The objects that are eventually recovered or recalled are those with the strongest links to the cue item.
References:
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