What Is Long-Term Memory?

Long-term memory refers to the transfer of information from short-term memory into long-term storage in order to create enduring memories. This type of memory is unlimited in capacity and stable—lasting for years or even a lifetime. Short-term memories can become long-term memories through a process known as consolidation.

Long-term memory can be further subdivided into two different types: explicit (conscious) and implicit (unconscious) memory. If you can remember something that happened more than just a few moments ago, whether it occurred just hours ago or decades earlier, it is long-term memory.

Long term memory is important because it helps us recall major events in our lives. We also use long-term memory to access the skills and behaviors that we've learned which contribute to our survival.

Types of Long-Term Memory

Long-term memory is usually divided into two types—explicit and implicit.

• Explicit memories, also known as declarative memories, include all of the memories that are available in consciousness. Explicit memory can be further divided into episodic memory (specific events) and semantic memory (knowledge about the world). Examples of this type of long-term memory include being able to recall your high school graduation or remembering the year that the U.S. declared its independence.
• Implicit memories are those that are mostly unconscious. This type of memory includes procedural memory, which involves memories of body movement and how to use objects in the environment. Knowing how to drive a car or use a computer are examples of procedural memories.

Long-term memories are often outside of the conscious mind. This information is largely outside of our awareness but can be called into working memory to be used when needed. Some memories are relatively easy to recall, while others are much harder to access.

Duration of Long-Term Memory

Through the process of association and rehearsal, the content of short-term memory can become long-term memory. Long-term memories can last from a matter of days to as long as many decades.

There are a number of factors that can influence how long information endures in long-term memory:

• The way the memory was encoded in the first place can play a significant role. If you were very aware and alert when you had the experience, then the memory will probably be a lot more vivid.
• The number of times you access a memory can also play a role in the strength and duration of that memory. Not surprisingly, memories that you recall often tend to stick around and become much stronger.

Information that is of greater importance leads to a stronger recall. You can usually remember important events such as your wedding day with much greater clarity and detail than you can more ordinary days.

How Long-Term Memory Forms

The information-processing model of memory characterizes human memory as being like a computer. Information enters short-term memory (a temporary store), then some of this information is transferred into long-term memory (a relatively permanent store), much like information being saved to the hard disk of a computer.

Memories that are frequently accessed become stronger and easier to recall. Accessing these memories over and over again strengthens the neural networks in which the information is encoded, leading to easier recollection of the information.

When information is needed, it is called forth out of this long-term storage using environmental cues, much like accessing a saved folder on your computer. However, these saved memories can be changed or sometimes even lost altogether. Memories that are not recalled often can sometimes weaken or be replaced by other information.

Long-Term Memory Changes

Studies suggest that memories are not saved in a static state, then pulled up with perfect clarity. Instead, researchers have found that memories are transformed or changed every single time they are accessed.

Neurons first encode memories in the cortex and hippocampus. Each time a memory is recalled, it is then re-encoded by a similar, but not identical, set of neurons.

Accessing memories often helps make them stronger, yet the research has found that this re-encoding can have an impact on how the information is remembered. Subtle details may change, and certain aspects of the memory may be strengthened, weakened, or even lost altogether depending on which neurons are activated.

Fragility of Long-Term Memory

Long-term memory can be surprisingly fragile and susceptible to change, misinformation, and interference. Memory expert Elizabeth Loftus has demonstrated how easily false memories can be triggered. In one of her most famous experiments, she was able to get 25% of her participants to believe in a false memory that they had once been lost in a shopping mall as a child.

Why is long-term memory so susceptible to these inaccuracies? In some cases, people miss important details about events. To fill in these missing gaps in information, the brain sometimes fabricates details that seem to make sense.

A Word From Verywell

Long-term memory plays a vital role in daily life, allowing you to build a foundation of information that allows you to live your life. While it is easy to think of memories as something similar to files in a computer, research has shown that long-term memory is both enduring and susceptible to error.