Types of memory: short term, long term and sensory (with examples)

The human being has three types of memory essential: the short-term memorythe long-term memory and the sensory memory.

Short-term memory is dedicated to retaining information for short periods of time. Long-term memory, on the other hand, has a greater temporality, usually transcending the passage of years.

Sensory memory, on the other hand, consists of all the processes dedicated to selectively capturing brief stimuli.

Memory refers to different brain processes whose purpose is to interpret, store and retrieve information. In this sense, both short-term and long-term memory are involved in different cognitive processes that help shape learning, intelligence and memories.

Short-term memory

Short-term memory (STM), also called active memory or secondary memory, is responsible for processing sensory stimuli and converting them into information that will be stored for very short periods of time.

The duration of a stimulus in short-term memory does not exceed 40 seconds, while the number of stimuli that can be perceived ranges from two to seven stimuli.

Despite the short time in which information is available in active memory, it is of great value in cognitive processes linked to logical reasoning and problem solving.

Moreover, if the stimulus is repeated persistently, it will no longer be stored in short-term memory, but will pass directly to long-term memory. This fact is crucial to understand that active memory is not a store of memories but an active system that provides information to long-term memory.

For this reason, if short-term memory suffers some kind of damage, either for pathological reasons, aging processes, etc., this will directly affect the acquisition of new skills, since they will not have access to long-term memory.

Types of short-term memory

Short-term memory is divided into 4 sub-systems that specialize in different types of stimuli:

• Executive system: responsible for regulating all short-term memory processes.
• Episodic storeThe episodic store is the system in charge of processing various stimuli and converting them into a representation with visual, verbal, spatial and temporal information.
• Phonological loop:is the system in charge of retaining alpha-numeric verbal information (letters and numbers).
• Visuospatial diaryis the system that retains information in the form of images.

Examples of short-term memory

Short-term memory is permanently active. Some everyday activities in which it is involved are:

• Remembering names of people.
• Remembering addresses.
• Remembering digits or series of numbers (telephone numbers, car license plates).
• Remembering faces of people or concrete images (the color of a car).

Long-term memory

Long-term memory (LTM) or inactive memory is the information storage system capable of retaining stimuli for time lapses ranging from hours to years.

The ability to store information and to keep it immediately available without being forgotten depends on several factors:

• The depth with which the stimulus was processed.
• The associations made to retain the information (some people remember long series of numbers because they associate them in a particular way).
• The number of times the information has been recalled (the more times something is recalled or recapitulated, the more difficult it is to forget).

Long-term memory depends on short-term memory, since the latter is the gateway to stimuli that, if repeated regularly, become part of inactive memory.

Types of long-term memory

Inactive or long-term memory is divided into two major systems:

Explicit memory

Also called declarative memory, it is responsible for storing information that is consciously available. In turn, it is divided into two subcategories:

• Episodic memorystores information about specific moments in time and space.
• Semantic memorysemantic memory: retains general information, which allows a better understanding of the world, even if the details are unknown.

Implicit or procedural memory

Also called non-declarative memory, it is the system in charge of retaining information linked to motor skills.

Examples of long-term memory

Some examples of the use of long-term memory that we make in everyday life, are:

• Recalling a childhood episode.
• Remembering that pressing a button can turn a device on or off.
• Remembering how to ride a bicycle after years of inactivity.

Sensory memory

Sensory memory involves all the processes of encoding external stimuli for very short periods of time and in a selective manner. In that sense, it can be confused with short-term memory, however, the period of permanence of the information is much shorter, lasting only a few milliseconds.

Depending on the type of stimulus and its relevance, this information can be discarded or it can pass to short-term memory, where it will remain a few seconds longer.

Types of sensory memory

Sensory memory is subclassified into:

• Iconic memory: it is in charge of processing visual stimuli.
• Echoic memoryauditory information processing.
• Olfactory memory: registers odors.
• Haptic memoryhaptic memory: processes information captured by the sense of touch.
• Taste memory: registers flavors.

Examples of sensory memory

• The smells we perceive when we walk down the street (there are many stimuli and not all of them stay in our memory).
• The sounds, noises and voices that we register quickly at a party.
• The textures we perceive when we touch everyday objects.

See also: Short-term and long-term memory