Atkinson and Shiffrin’s 1968 model of memory outlines that memory consists of three distinct forms: sensory memory, short-term memory and long-term memory. Sensory memory is the brief storage of information from our senses – sight, sound, touch, etc. Short-term or working memory stores limited amounts of information for a short time, while long-term memory is the repository for any information that needs to be remembered over a long period of time.

Sensory memory

Sensory memory refers to the ability of our senses to remember small amounts of information almost instantaneously. This type of memory, sometimes referred to as iconic or echoic memory, was first proposed by psychologists in his 1968 model, but was later added into their research.

This information therefore stores in our sensory memory which retains it for a very short period of time.

Duration: ¼ to ½ second

Short-term memory

Short-term memory (STM), as proposed by the Atkinson-Shiffrin model, is the second stage of memory.

It is a short-term storage system in which information that has been acquired through physical or emotional stimuli is temporarily held and can then be used for specific tasks or stored in long-term memory.

STM duration seems to be between 15 and 30 seconds and capacity around 7 items.

The magic number 7 (plus or minus two) provides evidence of short-term memory capacity. Most adults can store between 5 and 9 items in their short-term memory. 

Long-term memory

Long-term memory is the capacity for humans to store information over extended periods of time. It is a component of the Atkinson-Shiffrin memory model which describes how memories are encoded, stored and recalled.

Long-term memory allows us to retain information and skills for an indefinite period of time and form meaningful connections between different concepts that can help with understanding complex topics better.

Theoretically, the capacity of long-term memory could be unlimited, with the main constraint to recall being accessibility rather than availability.

The duration can be a few minutes or a lifetime. The suggested coding modes are semantic (meaning) and visual (pictorial) but can also be acoustic.