Every day we are obligated to work out challenges and problems that call upon our ability to keep issues clearly organized and prioritized in mind so that we can work out solutions.  From putting together a grocery list to solving simple equations when writing out a weekly or monthly budget, facts, figures, and mountains of information (relevant and irrelevant) assault our senses continually.  If we were unable to sift through the chaotic streams of data, line up the facts, and then quickly resolve such issues so we can move on to the next concern, our minds would become cluttered and confused due to a catastrophic logjam. 

Fortunately, our brains are equipped with a working memory function (formerly known as 'short term memory'), which serves as a cognitive conveyor belt system that organizes information to be effectively targeted, resolved, and dispensed with efficiently.  Even when we're in the zone and at the top of our game mentally, we can still experience a sense of overwhelm that brings with it anxiety and stress, which can lead to costly mistakes or even procrastination, feeling we have too much on our plate.
 
A 2008 scientific study conducted by University of Missouri-Columbia and published in the Proceedings of the National Academy of Sciences asserts that every person has a limited number of things they can deal with at any given moment, mentally.  Jeff Rouder, an Associate Professor of Psychology stated, "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."

The number of slots possessed by the average person had been estimated to be around seven (plus or minus two); a proposition popularized by professor George Miller of Princeton, in the 1950's.  More recently, studies contend that the number ranges from as high as five slots to as few as one, with any impressive ability to deal with more items than available slots being attributed to a phenomenon called 'Chunking', which is combining several bits of information into one perceptually cohesive item so that it can fit into a single slot.  An example of chunking would be to take the letters C, I, A, F, B, I, F, D, and A (a total of nine items, exceeding the slot allotment) and chunk them into three slots by combining them into CIA, FBI, and FDA.

Working memory is closely related to attention because it requires controlled attention in order to hold numerous items in mind simultaneously or for an extended time. Without attention to feed the process, the targets can fade, become interrupted by other data, or be entirely replaced by more information.

People with high working memory capacity have stronger attention control. On the whole, higher capacity consists mainly of higher endurance, that is, the ability to hold the data for use rather than let the data slip away.

Those with a weaker control over their attention are more easily distracted.  Distraction interferes with one's ability to maintain items in working memory.  Consequently, when you improve your power of concentration, you simultaneously strengthen your working memory.

A 2005 report in the Journal of the American Academy of Child & Adolescent Psychiatry says that parents of children diagnosed with ADHD who had those kids undergo working memory training reported a reduction in their children's hyperactivity and inattention three months after the intervention, while parents of another group of ADHD children who received no working memory training reported no improvements.

The use of working memory to accomplish a task requires exertion and control of the faculty of attention, especially when the task involves holding several items in mind simultaneously.  If a person's working memory capacity is five slots (meaning they can hold five items, such as five randomly spoken numbers which they can then repeat back), they must use controlled attention in order to maintain those five items in memory long enough to be able to perform the objective.  If attention wanders away from the target, then the target itself risks being displaced by whatever new item the attention 'lands on'.

This indicates that there are two forms of cognitive exertion involved, one form of exertion in targeting attention and holding it in place; and a second form of mental effort in maintaining the clarity and integrity of the working memory target(s).  As an example, the numbers 3, 8, 2, and 5, held in memory, require willful effort in order to forestall the entirely natural process of disintegration or 'fading away' of the memory item within the slot.

When working memory is 'improved', that improvement is comprised mainly of enhancing its duration (endurance) - maintaining clarity and integrity of a target for longer periods of time - rather than increasing the number of targets, since most scientific studies on the topic declare that the number of working memory slots are fixed.

A second characteristic involved in working memory training is that of practiced effort ('the practice effect), the result of which brings increased skill at using and applying working memory for improved attention control, creativity, accuracy, and productivity. 

Third, working memory training improves mental flexibility through rigorous rehearsal at manipulating the items held within the limited number of cognitive slots, thereby putting them to some form of practical work.  If you the reader can imagine a sharp pencil, a piece of paper, the word "dog", and then animate the pencil so that, in your imagination, you can move it so that it presses its tip against the surface of the paper and actually writes out the word "dog", then you understand how items occupying the working memory slots can be pressed into service, mentally.

So, we now know that working memory is the brain function that allows us to operate better academically, shine brighter in a career or business, and impress others, socially.  We know that there is a natural limit for each of us, but that working memory training can maximize our natural allotment for improved mental power and better performance in any area of life.  Finally, we know that improved mental concentration and working memory training go hand in hand (can't have one without the other), resulting in increased attention control and stronger mental focus.