Short term memory has three key aspects: 1. limited capacity (only about 7 items can be stored at a time) 2. limited duration (storage is very fragile and information can be lost with distraction or passage of time) 3. encoding (primarily acoustic, even translating visual information into sounds).
Miller’s “Magic Number 7” provides evidence for the capacity of short term memory (STM). Many adults can store between 5 and 9 things in their STM. He called it the Magic Number 7 because short term memory can hold 7, plus or minus 2, because it only has a limited capacity. Miller never explained that we could chunk information together, like compressing the information to collect more information. Miller’s theory is supported by various studies, such as Jacobs. The digit span test used ever letter in the alphabet and numbers, except from “w” and “7” as they only had two syllables. He concluded that people found it easier to recall numbers rather than letter. The average memory span for letters was 7.3 whilst the span for numbers was 9.3.
Other psychologists, Atkinson and Shiffrin, thought the duration of STM was between 15 and 30 seconds. They concluded that we can keep items in our memory if we repeat them verbally, known as acoustic encoding, which is known as rehearsal. A technique called “Brown-Peterson Technique”, prevents the possibility of retrieving the items by having the participants count backwards in 3s, they concluded that the longer the delay, the less information was recalled. The rapid loss of information from memory when rehearsal is prevented is taken as an indication of short term memory having a limited duration.
Baddeley and Hitch had found out that instead of all this information going into one place, there are different systems for different types of information. There are three parts to the memory store: * Central Executive, which drives the