What Is Memory?
Memory is the faculty by which the brain encodes, stores, and retrieves information. It is a record of experience that guides future action.
Memory encompasses the facts and experiential details that people consciously call to mind as well as ingrained knowledge that surface without effort or even awareness. It is both a short-term cache of information and the more permanent record of what one has learned. The types of memory described by scientists include episodic memory, semantic memory, procedural memory, working memory, sensory memory, and prospective memory.
Each kind of memory has distinct uses—from the vivid recollections of episodic memory to the functional know-how of procedural memory. Yet there are commonalities in how memory works overall, and key brain structures, such as the hippocampus, that are integral to different kinds of memory.
In addition to memory’s role in allowing people to understand, navigate, and make predictions about the world, personal memories provide the foundation for a rich sense of one’s self and one’s life—and give rise to experiences such as nostalgia.
Memory loss is the unavoidable flipside of the human capacity to remember. Forgetting, of course, is normal and happens every day: The brain simply cannot retain a permanent record of everything a person experiences and learns. And with advancing age, some decline in memory ability is typical. There are strategies for coping with such loss—adopting memory aids such as calendars and reminder notes, for example, or routinizing the placement of objects at risk of getting lost.
In more severe cases, however, memory can be permanently damaged by dementia and other disorders of memory. Dementia is a loss of cognitive function that can have various underlying causes, the most prominent being Alzheimer’s disease. People with dementia experience a progressive loss of function, such that memory loss may begin with minor forgetfulness (about having recently shared a story, for example) and gradually progress to difficulty with retaining new information, recognizing familiar individuals, and other important memory functions. Professional assessment can help determine whether an individual’s mild memory loss is a function of normal aging or a sign of a serious condition.
Memory disorders also include multiple types of amnesia that result not from diseases such as Alzheimer’s, but from brain injury or other causes. People with amnesia lose the ability to recall past information, to retain new information, or both. In some cases the memory loss is permanent, but there are also temporary forms of amnesia that resolve on their own.
Though memory naturally declines with age, many people are able to stay mentally sharp. How do they do it? Genes play a role, but preventative measures including regular exercise, eating a healthy diet, and getting plenty of sleep—as well as keeping the brain active and challenged—can help stave off memory loss.
The science of memory also highlights ways anyone can improve their memory, whether the goal is sharpening memory ability for the long term or just passing exams this semester. Short-term memory tricks include mnemonic devices (such as acronyms and categorization), spacing apart study time, and self-testing for the sake of recalling information. Sleep and exercise are other memory boosters.
Through committed practice with memory-enhancing techniques, some people train themselves to remember amazing quantities of information, such as lengthy sequences of words or digits. For a small number of people, however, extraordinary memory abilities come naturally. These gifted rememberers include savants, for whom powerful memory coincides with some cognitive disability or neurodevelopmental difference, as well as people with typical intellects who remember exceptional quantities of details about their lives.
Memory is a key element in certain mental health conditions: Abnormal memory function can contribute to distress, or it can coincide with an underlying disorder. Forgetfulness is associated with depression; connections in memory, such as those involving feared situations or drug-related cues, are an integral part of anxiety and substance use disorders; and post-traumatic symptoms are entwined with the memory of traumatic experiences.
In fact, experiences such as distressing memories and flashbacks are among the core symptoms of post-traumatic stress disorder. For someone with PTSD, a range of cues—including situations, people, or other stimuli related to a traumatic experience in some way—can trigger highly distressing memories, and the person may seek to avoid such reminders.
As a feature of various mental disorders, aberrant or biased memory function can also be a target for treatment. Treatments that involve exposure therapy, for example, are used to help patients reduce the power of trauma-related memories through safe and guided encounters with those memories and stimuli associated with the trauma.
To learn more, see Memory and Mental Health.