Short-term memory is much more unstable than its long-term counterpart, as it is more likely to be affected by outside interference. The nature of how these kinds of memory interact with synaptic connections may affect their strength. Since short-term memory does not create new synaptic connections the way long-term memory does, it is weaker.


Quality of Short-Term and Long-Term Memory in Relation to Synaptic Connections

Short-term memory is the result of strengthening the preexisting proteins in the synapses. Contrastingly, long-term memory comes from the creation of new synaptic connections. In other words, long-term memory changes the anatomy of the brain, but short-term memory does not.   

Hofstra University

This is the way that neurons are able to communicate with each other. There is a small area of space between the axon and the dendrite where the information is shared. This can be done through chemical or electrical synapses.

Synapse

Long-term memory (LTM) is the system for continuous and permanent storage of information, characterized by a practically limitless capacity. It holds memories for extended periods, from minutes to a lifetime. Fundamentally, LTM is divided into two main categories: implicit memory, which is unconscious, and explicit memory, which involves conscious recall. Information within LTM is typically organized into complex, structured networks.

Long-Term Memory (LTM)

Short-term memory (STM) serves as a temporary storage system that processes incoming information from sensory memory. It is capable of retaining a limited amount of data for a brief duration of 15 to 30 seconds. While in this active state, short-term memory can also integrate new sensory input with existing knowledge retrieved from long-term memory. Although often confused with working memory, short-term memory is more accurately classified as a distinct sub-component within the broader working memory framework.

Short-term Memory (STM)

Mayford, M., Siegelbaum, S. A., & Kandel, E. R. (2012). Synapses and memory storage. Cold Spring Harbor perspectives in biology, 4(6), a005751. https://doi.org/10.1101/cshperspect.a005751

Synapses and Memory Storage

A chemical synapse facilitates neuronal communication through the release of chemical messengers called neurotransmitters. This process represents the chemical portion of the overall electrochemical signal, where neurotransmitters travel across the synaptic space to transmit information. This method is the most common type of synapse in the brain but is slower than an electrical synapse.

Chemical Synapse

An electrical synapse is a specialized connection where two neurons are physically linked by structures called gap junctions. These junctions contain channels that permit electrical current to pass directly from the presynaptic to the postsynaptic cell. This direct physical connection allows for extremely rapid, almost instantaneous, signal transmission between neurons.

Electrical Synapses

Memory's Relationship to the Synapses

Growth factors in long-term potentiation result in the creation of new synapses. This results in synaptic plasticity.

Growth Factors in Long-Term Potentiation

1. Encoding into Short-term Memory 
2. Consolidation into Long-term Memory 
3. Retrieval into Future Behavior 

System for Creating and Retaining Memories 

Abraham, W. C., Jones, O. D., & Glanzman, D. L. (2019). Is plasticity of synapses the mechanism of long-term memory storage? Nature Partner Journals: Science of Learning, 4(9), 1-8. https://doi.org/10.1038/s41539-019-0048-y



Abraham et al., 2019

Martin, S. J., Grimwood, P. D., & Morris, R. G. (2000). Synaptic plasticity and memory: an evaluation of the hypothesis. Annual review of neuroscience, 23, 649–711. https://doi.org/10.1146/annurev.neuro.23.1.649

Martin et al., 2000

Rehearsal is a memory-enhancing strategy that involves the conscious repetition of information that needs to be remembered. According to Craik & Watkins (1973), this process is utilized to transfer information from short-term memory to long-term memory.

Rehearsal

Once information reaches long-term memory, it must be consolidated. This consolidation process occurs at two distinct stages: at the synaptic level, which takes a few hours, and into the broader memory system, which can take weeks or longer.

Levels of Memory Consolidation

According to the theory by Collins & Loftus (1975), long-term memories are structured in semantic, or associative, networks. These networks consist of interconnected concepts, with the connection strength determined by the frequency of their association. The specific organization of these networks is unique to each individual, as they are shaped by personal experiences.

Semantic Networks in Long-Term Memory

Long-term memory is broadly categorized into two main types: explicit and implicit. This distinction is crucial because various factors, such as the aging process, specific kinds of brain trauma, and certain disorders, can selectively affect one type of memory while leaving the other intact.

Types of Long-Term Memory: Explicit and Implicit

Analyze the individual's actions described in the case study below. Identify the two primary categories of long-term memory being demonstrated and explain how each part of the scenario corresponds to one of these categories.

Analyzing Memory in Action

Long-term memory is organized hierarchically into explicit memory and implicit memory. Explicit memory is further divided into episodic memory (for events and experiences) and semantic memory (for concepts and facts). Implicit memory is subdivided into procedural memory (for how to do things), priming (where stimulus exposure affects responses to a later stimulus), and emotional conditioning (for classically conditioned emotional responses).

Long-Term Memory Subsystems Hierarchy

A promising avenue for improvement of short-term memory (STM) capacity has been the introduction of mindfulness meditation (MM). Mindfulness interventions can improve attentional control and reduce psychological stress, two especially vital processes of working memory (WM) performance. 

Mindfulness approach to improving short-term memory (STM)

A helpful analogy for understanding short-term memory is comparing it to a computer screen. The information currently displayed on the monitor, such as an active document, represents short-term memory—it is immediately accessible but temporary. To retain this information permanently, it must be saved to the computer's hard drive, which corresponds to long-term memory. If the application is closed without saving, the data is lost, just as information in short-term memory is discarded.

Computer Screen Analogy for Short-Term Memory

Peterson and Peterson (1959) investigated short-term memory using trigrams, which are three-letter sequences such as CLS. Participants were asked to recall these trigrams after delays ranging from 3 to 18 seconds. The results showed that participants recalled approximately 80% of the trigrams after a 3-second delay, but this dropped to only 10% after an 18-second delay, leading the researchers to conclude that short-term memory decays within 18 seconds.

Peterson and Peterson's Study on Short-Term Memory Decay

Based on the principles of information storage, explain why the person likely forgot the phone number. Your explanation should focus on the characteristics of the specific, temporary memory system being used to hold the number before dialing.

Forgetting a Phone Number

Although the terms 'short-term memory' and 'working memory' are frequently used interchangeably, they represent distinct psychological concepts. Short-term memory specifically refers to the temporary storage system holding incoming sensory information. In contrast, working memory is a more comprehensive system that encompasses this temporary storage. Consequently, short-term memory is most accurately conceptualized as a sub-component operating within the larger working memory framework.

Distinction Between Short-Term Memory and Working Memory

The retention of information in short-term memory is influenced by two factors: memory trace decay and interference.

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