Describe and evaluate the multi-store model of memory. [16 marks]

ESSAY HINT: This is a fairly straightforward question. Students should include sufficient detail about the model's structure and processes. Diagrams are permitted, but students must explain what the diagram shows. When evaluating supporting studies, methodological issues should be clearly linked to whether the evidence supports or challenges the multi-store model.

According to Atkinson and Shiffrin’s multi-store model (MSM), memory consists of three separate stores: the sensory register (SR), short-term memory (STM) and long-term memory (LTM). Each store differs in its coding, capacity and duration, and information is transferred between them through attention, rehearsal and retrieval.

Information from the environment enters the 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, while echoic memories may last for several seconds. Information that receives attention passes to STM, whereas unattended information is quickly lost through trace decay or displacement.

STM mainly codes information acoustically. It has a limited capacity of approximately 7 ± 2 items, although chunking can increase the amount held, and a duration of approximately 18–30 seconds. Maintenance rehearsal, involving the repetition of information, retains information in STM and, if prolonged, transfers it to LTM.

LTM mainly codes information semantically, according to its meaning. It has a potentially unlimited capacity and a duration of up to a lifetime. Through retrieval, information passes from LTM to STM, where it can be consciously recalled and used.

One strength of the MSM is the substantial laboratory evidence supporting its different components. Baddeley found that STM primarily encodes information acoustically, whereas LTM primarily encodes information semantically. Jacobs demonstrated the limited capacity of STM, while Peterson and Peterson found that its duration is approximately 18 seconds when rehearsal is prevented. These studies were conducted under controlled conditions, reducing the influence of extraneous variables. Each study therefore supports a different feature of the stores proposed by the MSM. The convergence of evidence from several studies investigating different characteristics increases the model's credibility as an explanation of memory.

Further support comes from the case study of Clive Wearing. After contracting herpesviral encephalitis, Wearing suffered damage to his hippocampus, an area involved in transferring information from STM to LTM. Although he could recall information from before his illness, he could retain new information for only 20–30 seconds and was unable to form lasting new memories. This supports the distinction between STM and LTM because his STM remained relatively intact while his ability to transfer new information into LTM was severely impaired. However, conclusions drawn from one unusual individual may not generalise to everyone, limiting the extent to which this case supports the MSM as a universal model.

Furthermore, the MSM may exaggerate the importance of rehearsal. It proposes that prolonged rehearsal transfers information from STM to LTM, yet lasting memories may form without rehearsal. Brown and Kulik documented “flashbulb memories”: vivid memories of emotionally significant events. For example, many people remember where they were when they heard about Princess Diana’s death or the 9/11 attacks, despite not rehearsing the information beforehand. This suggests that factors such as emotional significance can produce long-lasting memories without prolonged rehearsal. Therefore, the MSM provides an oversimplified, linear account of how information enters LTM.