Understanding Memory: Short-Term, Long-Term, and Disorders

Short-Term Memory

Short-term memory is the center of consciousness, encompassing all thoughts, experiences, or information within a given period. Its duration is typically 15 to 20 seconds, or a maximum of 30 seconds. After this period, information is lost if not consolidated.

Information must be consolidated from short-term memory to long-term memory. Conversely, retrieving information from long-term memory requires transferring it back to short-term memory for use.

Long-Term Memory

Long-term memory is the lifelong repository of all the information we accumulate. Due to its unlimited capacity and duration, it is the richest and most complex memory structure, but also the most challenging to investigate.

While short-term memory is based on the physical properties of things, long-term memory relies on their meanings. Several classifications have been proposed for the structure of long-term memory. The best-known, by Tulving, identifies three separate subsystems:

• Episodic Memory: Stores past experiences; it is autobiographical memory.
• Semantic Memory: Contains each person's worldview, that is, general knowledge about the world.
• Procedural Memory: Stores knowledge of how to do things, such as skills.

Forgetting

Remembering and forgetting correspond to different types of information processing. When we speak of forgetting, we refer to the loss of information in long-term memory. A powerful factor causing this loss is interference. There are two types of interference:

• Retroactive Interference: New information interferes with the retrieval of previously stored information.
• Proactive Interference: Previously stored information prevents the acquisition of new information.

Memory Disorders

Amnesia

Amnesia is the partial or total loss of memory function. Types of amnesia include:

• Retrograde Amnesia: Memory loss for the period preceding the disorder.
• Anterograde Amnesia: Memory loss for events occurring after the disorder. Notably, individuals can still remember events that occurred before the onset of amnesia.
• Localized Amnesia: Memory loss corresponding to a specific period. This type of amnesia is often associated with mental disorders and coma states.
• Selective Amnesia: Memory loss corresponding to specific experiences. Freud described this type of amnesia. Selective amnesia can exclude memories of situations that cause anxiety.

Hypermnesia

Hypermnesia is a memory impairment characterized by an unusually vivid or detailed recall. Individuals may experience unpleasant situations more intensely and frequently.

Paramnesia

Paramnesia is characterized by distorted or false memories. In these cases, details are added to memories that did not occur in the original event. The phenomenon known as "déjà vu," where people experience an intense but false feeling of having previously seen a situation, object, or landscape, is part of the study of paramnesia.