A mind is a terrible thing to waste, but humans may have even less to work with than previously thought. University of Missouri researchers found that the average person can keep just three or four things in their "working memory" or conscious mind at one time. This finding may lead to better ways to assess and help people with attention-deficit and focus difficulties, improve classroom performance and enhance test scores.
"Most people believe the human mind is incredibly complex," said Jeff Rouder, associate professor of psychology in the MU College of Arts and Science. "We were able to use a relatively simple experiment and look at how many objects can be in maintained in the human conscious mind at any one time. We found that every person has the capacity to hold a certain number of objects in his or her mind. Working memory is like the number of memory registers in a computer. Every object takes one register and each individual has a fixed number of registers. Limits in working memory are important because working memory is the mental process of holding information in a short-term, readily accessible, easily manipulated form where it can be combined, rearranged and stored more productively."
"We know that this kind of memory is really important in daily life," said co-author Nelson Cowan, psychology professor at Mizzou and an expert in working memory theory. "If a person is trying to do a math problem, there are partial results to keep in mind as that person solves the problem. When people are going to do any tasks in the house-like remembering the location of keys, turning off the stove, combining ingredients for a cake or recalling a phone number-they use working memory to keep in mind all the different aspects of the tasks."
Rouder said that to remember a series of items, people will use "chunking," or grouping, to put together different items. It can be difficult for someone to remember nine random letters. But if that same person is asked to remember nine letters organized in acronyms, IBM-CIA-FBI, for example, the person only has to use three slots in working memory. The difficulty in measuring working memory capacity is assuring that each item presented cannot be grouped together with others to form a larger chunk.