6.4.2. Short-term Memory

You will perhaps agree that we do not attend to all the information that impinge on our senses. Information that is attended to enters the second memory store called the short-term memory (abbreviated as STM), which holds small amount of information for a brief period of time (usually for 30 seconds or less).

Short-term memory (STM) acts as a temporary holding place for information we focus on. When we encounter a lot of sensory input (like sights and sounds), only a fraction of that information captures our attention. This selective attention allows some information to transition into STM. Once in STM, the information can be temporarily stored for a limited duration—typically around 30 seconds. If we do not actively engage or rehearse this information, it will quickly fade away.

Think of STM like a notepad app on your phone. You can jot down a quick thought or a to-do item, but if you don’t save it or revisit it in a short time frame, it’s easy to lose that note. If you think of something and write it down instantly, that’s like how our brain captures short-term information.

Atkinson and Shiffrin propose that information in STM is primarily encoded acoustically, i.e. in terms of sound and unless rehearsed continuously, it may get lost from the STM in less than 30 seconds.

Encoding in short-term memory heavily relies on auditory processing—essentially, we tend to remember things in the way they sound. For instance, if you hear a new phone number, you might catch yourself repeating it aloud to grasp it better. If you don’t rehearse it right away, it gets lost quickly due to the STM's fleeting nature.

Imagine you hear a catchy song on the radio and sing along. If you don’t listen to the song again or think about it later, you might forget the lyrics soon after. This illustrates how short-term memory captures sound and the importance of repetition in memory retention.

Note that the STM is fragile but not as fragile as sensory memory.

Short-term memory is vulnerable, meaning it can easily be disrupted if not actively managed. While it cannot store as much information as our sensory memory, it is certainly more stable than sensory memories, which vanish in mere seconds. Without rehearsal or attention, the information in STM is prone to decay quickly, underscoring the importance of actively maintaining what we wish to remember.

Think of STM as a holding pen for a few apples. If the apples aren't checked on regularly (like rehearsing), they might spoil or go bad quickly, compared to a well-stocked fridge (long-term memory), which keeps things fresh for a longer time.

From the STM, information enters the long-term memory through elaborative rehearsals. As against maintenance rehearsals, which are carried through silent or vocal repetition, this rehearsal attempts to connect the ‘to be retained information’ to the already existing information in long-term memory.

In order to move information from short-term to long-term memory, we must engage in a deeper level of processing known as elaborative rehearsal. This technique involves making associations and connecting new information with what we already know, which helps embed it more firmly in our long-term memory. Simple repetition (maintenance rehearsal) may keep the info in STM but won't secure it for future use.

Consider when you learn a new concept in school, such as photosynthesis. If you just repeat the steps without understanding, you might forget. However, if you link the concept to related topics, like how plants grow or the importance of sunlight, it becomes easier to remember because you’ve created a web of connections.

Through chunking it is possible to expand the capacity of STM which is otherwise 7+2.

Chunking is a strategy used to enhance the capacity of short-term memory. Instead of trying to memorize a string of individual items, breaking them into larger, meaningful units (or chunks) can help us remember better. This enables us to fit more information into our limited STM capacity, which is generally thought to be about 7 items.

For example, if you’re trying to remember the numbers 1-9-1-9-4-7-1-9-4-9-2-0-0-4, it may be overwhelming. Instead, you could chunk them into '1947', '1949', and '2004', which connects them to significant historical events. This makes it much easier to remember.

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