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Memory comprises three systems: sensory memory, short-term memory (STM), and long-term memory (LTM). Sensory memory captures raw environmental input for seconds or less, like a brief car horn sound lingering momentarily. STM actively processes this information for short durations, such as remembering a phone number long enough to dial it. LTM stores important information for extended periods, ranging from minutes to a lifetime, including personal experiences and skills.

Sensory memory captures raw sensory input from the environment and holds it for just a few seconds or less. For example, when you glimpse a scene from a moving car or hear a loud sound, the impression lingers briefly in your mind even after the stimulus stops. This allows you to replay and process the sensory information momentarily before it fades, enabling initial perception of your surroundings.

Short-term memory actively processes information received from sensory memory and transforms it into more meaningful content. For instance, STM converts visual patterns into recognizable shapes and objects. It holds information long enough for immediate tasks, such as remembering directions to reach a nearby location or dialing a phone number, but only for a short duration before the information fades.

Long-term memory stores important information for extended periods, ranging from minutes to a lifetime, with no capacity limits. It retains personal experiences, knowledge, and skills such as knowing how to ride a bicycle or speaking a second language. When you travel to the same place multiple times, the route eventually transfers from short-term to long-term memory, allowing lifelong retention and recall.

Information begins in sensory memory as raw environmental input, then moves to short-term memory where it is actively processed and transformed into meaningful content. With repeated exposure or importance, information transfers to long-term memory for extended storage. For example, repeatedly traveling a route moves it from momentary sensory impressions through active processing in STM to permanent storage in LTM.

The duration differences enable efficient information processing: sensory memory provides momentary awareness, STM allows active manipulation of information for immediate tasks, and LTM enables learning and everyday functioning by retaining knowledge long-term. This progression allows individuals to build upon previous experiences and knowledge, transforming fleeting sensory impressions into lasting memories that support complex cognitive abilities and skill development.

Sensory memory has limited capacity and duration, holding raw input for seconds or less. Short-term memory holds information longer but still briefly, with limited capacity for active processing. Long-term memory has virtually unlimited capacity and can retain information for a lifetime. These differences reflect each system's function: sensory memory provides initial perception, STM enables immediate problem-solving, and LTM supports knowledge accumulation and skill retention.