It has unlimited capacity. Selective attention determines what information moves from sensory memory to short-term memory . STM is most often stored as sounds, especially in recalling words, but may be stored as images. STM is vulnerable to interruption or interference. This is relatively permanent storage.
Information is stored on the basis of meaning and importance.
Miller's Magic Number George Miller's classic 1956 study in found that the amount of information which can be remembered on one exposure is between five and nine items, depending on the information. The brief duration of these items last from 3 to 20 seconds. Decay appears to be the primary mechanism of memory loss. After entering sensory memory, a limited amount of information is transferred into short-term memory. Acoustic memory - The ability to hold sounds.