Understanding Short-Term Memory

Memory is the retention of information over time. Although the word memory may conjure up an image of a singular, “all-or-none” process, it is clear that there are actually many kinds of memory: sensory register, short-term memory, long-term memory, visual memory, auditory memory, and sequential memory, to name but a few.

When you are trying to recall a telephone number that was heard a few seconds earlier, the name of a person who has just been introduced, or the substance of the remarks just made by a teacher in class, you are calling on short-term memory, or working memory. Short-term memory lasts from a few seconds to a minute or so, and can be compared to the control tower of a major airport, responsible for scheduling and coordinating all incoming and outgoing flights. You need this kind of memory to retain ideas and thoughts as you work on problems. In writing a letter, for example, you must be able to keep the last sentence in mind as you compose the next. To solve an arithmetic problem like (3 X 3) + (4 X 2) in your head, you need to keep the intermediate results in mind (i.e., 3 X 3 = 9) to be able to solve the entire problem.

A poor short-term memory may lead to difficulties in processing, understanding and organization. Students who have deficits in registering information in short-term memory often have difficulty remembering instructions or directions they have just been given, what was just said during conversations and class lectures and discussions, and what they just read, says Glenda Thorne, Ph.D. Research has confirmed that verbal short-term memory deficits are a common characteristic of children with reading problems and may markedly increase the difficulty of learning to read.

Unfortunately, even if a student has excellent long-term memory, his ability to use it is limited by how much information has ‘leaked’ while it was in his short-term memory. In this way, short-term memory can cripple someone who has many areas of strength but is unable to use them to their fullest potential.

Distinction between short-term and working memory

The distinction between short-term memory and working memory is an ongoing debate, as the terms are often used interchangeably. There are scholars who claim that some kind of manipulation of remembered information is needed in order to qualify the task as one of working memory. Repeating digits in the same order they were presented would thus be a short-term memory task, while repeating them backward would be a working memory task. Another viewpoint is that of Nelson Cowan, who says short-term memory refers to the passive storage of information when rehearsal is prevented with storage capacity around four items. When rehearsal is allowed and controlled attention is involved, it is a working memory task and the capacity is closer to seven items..

Article continues below...  

Edublox Multisensory Cognitive Programs
undamental solutions to learning deficits –

Video: Overcoming dyslexia and developmental delays

Vivienne was adopted from China at age 5. This video is about Susan helping her 11-year-old daughter overcome developmental delays, including dyslexia. They started with the Edublox program 13 weeks ago. This is their story. Continue Reading

Susan, Vivienne's mom, US Edublox Online Tutor August 22, 2021

<< Prev
Next >>

Testing short-term memory capacity

There are two ways in which capacity is tested, one being span, the other being recency effect.

The magic number 7 (plus or minus two) provides evidence for the capacity of short-term memory. Most adults can store between 5 and 9 items in their short-term memory.  This idea was put forward by Miller (1956) and he called it the magic number 7. He though that short-term memory could hold 7 (plus or minus 2 items) because it only had a certain number of “slots” in which items could be stored.

However, Miller didn’t specify the amount of information that can be held in each slot. Indeed, if we can “chunk” information together we can store a lot more information in our short-term memory.

Miller’s theory is supported by evidence from various studies, such as Jacobs (1887). He used the digit span test with every letter in the alphabet and numbers apart from “w” and “7” because they had two syllables. He found out that people find it easier to recall numbers rather than letters. The average span for letters was 7.3 and for numbers it was 9.3.

The order in which information is learned determines how reliably it will be recalled. The first item in a list is initially distinguished from previous activities as important (primacy effect) and may be transferred to long-term memory by the time of recall. Items at the end of the list are still in short-term memory (recency effect) at the time of recall.

Short-term memory test

Read a row of numbers at a rate of one second per number and look away. How many numbers can you remember?


7        2

3        8        5

2        7        4        1

4        9        5        2        6

8        1        6        3        5        9

3        5        7        4        1        8        2

6        8        1        5        9        2        7        4

4        9        7        3        8        5        1        7        2

7        3        2        8        6        2        9        5        1        4

If you can remember only three or less, then your short-term memory is poor; four to seven, then your short-term memory is average; eight to ten, then your short-term memory is good.

© Edublox

Edublox Online Tutor offers multisensory cognitive training that enables learners to overcome reading problems and learning challenges and reach their full potential. Over the last 30+ years, the company behind the Online Tutor e-learning platform, Edublox, has helped thousands of children to read, learn and achieve through home kits and learning clinics internationally. Our programs are founded on pedagogical research and more than three decades of experience demonstrating that weak underlying cognitive skills account for the majority of learning difficulties. Specific cognitive exercises can strengthen these weaknesses leading to increased performance in reading, spelling, writing, math and learning.


McLeod, S. A. (2009). Short Term Memory. Retrieved from www.simplypsychology.org/short-term-memory.html

Thorne, G. (2006). 10 Strategies to Enhance Students’ Memory. Retrieved from http://www.cdl.org/articles/10-strategies-to-enhance-students-memory/