Final answer:
Sensory memory serves as the initial stage of memory, briefly holding large capacities of sensory information such as sights and sounds. Visual information registers under a second, while auditory information can last several seconds. Most sensory impressions are discarded unless they move on to short-term memory for further processing.
Step-by-step explanation:
Sensory memory is the initial, temporary storage of sensory information, such as sights, sounds, and tastes. This memory type is part of the Atkinson-Shiffrin model, which describes how stimuli from the environment are processed into our memory system. The capacity of sensory memory is large; however, it retains information only for a very brief period.
Specifically, the time for sensory information to register in the sensory memory is less than a second to a few seconds. For the visual sensory memory, often referred to as iconic memory, the registration time is under one second. In contrast, auditory sensory memory, known as echoic memory, can last up to several seconds.
Sensory memory holds sensory impressions momentarily and typically without conscious processing. Most of this information is discarded unless it is deemed valuable and is then moved into short-term memory (STM). STM has a capacity for holding about seven bits of information (7 plus or minus 2) before it is either forgotten or stored, and it deals with information that has been retrieved and is in use.
The overall purpose of sensory memory is to give the brain some time to process the incoming stimuli and decide whether it is worth paying attention to. If the information is considered important, it gets encoded into short-term memory and could eventually move into long-term memory for permanent storage based on further processing and rehearsal.