How to Measure Working Memory Capacity

Working memory is a key cognitive function that allows individuals to hold information in mind, while at the same time manipulating the same or other information. For example, multi-tasking requires working memory because a person must be aware of numerous activities simultaneously. Likewise, multiplying two large numbers in your head requires the use of working memory.

Consequently, working memory capacity is commonly measured by determining how many items a person can remember simultaneously for a short period of time. Someone who can remember all 10 digits of a phone number and repeat them back has a greater working memory capacity than someone who can only recall four. While working memory capacity can often be assessed using simple exercises, it is crucial to academic, professional, and social well being.

There are many tests available for measuring working memory capacity. Some measure visual working memory, whereby individuals recall visual information, others measure auditory working memory, the ability to recall auditory information.

Working Memory Increases and Decreases by Age
Studies show that working memory increases steadily throughout childhood and early adulthood, peaking between 18 and 25 years of age. For instance, a typical 19 year old can remember seven distinct items simultaneously, according to a recent study.* Working memory generally begins to decline after the age of 30 but can be strengthened and maintained through training or activities that demand its use.

Many children, adolescents, and adults have limited working memories that greatly impair their abilities to function in daily life. Working memory assessments are a great way of discovering if a person is operating at his or her highest potential.
The graph below indicates how one scientific study calculated working memory capacity increases and decreases by age.

The research, conducted by H. Lee Swanson at the University of California, Riverside, used a battery of working memory tests to determine the average working memory capacity of each age group.