Working Memory – How it Works

Working memory (WM) is not a single process, nor is it controlled by a single structure in the brain. Instead, it can be thought of as a “component process” that is the result of, made up of, or sometimes hard to distinguish from, a number of other cognitive processes, such as attention, inhibition, and shifting (cognitive flexibility). ^​1,2​

Working Memory Capacity

Unlike the near-limitless capacity of long-term memory, working memory “is highly limited in how much information can be held active simultaneously.”​^​1​ ​Research shows that while most people can remember only 3-4 simple items accurately, if the information is complex, that number can be smaller, or if the items are “chunked” (the “pairing, clustering, or grouping of discrete items into larger units that are processed and remembered as a whole”​^​2​​), then one can  hold more overall information in mind simultaneously.​^​1​

Capacity limits of WM can greatly differ depending on the specific task. For example, if a task relies on information stored in long-term memory rather than requiring information to be held in working memory itself, then WM performance increases. And if “fine details of complex objects” needs to be reported, performance will decrease.^​1​ 

In addition, WM capacity varies substantially between individuals. It appears that these variations “are determined primarily by variability in consistently deploying attentional control over what is stored in working memory, rather than the absolute amount of storage space per se.”​^​1​​ Furthermore, “[t]hese differences are highly stable over time and appear to be a core cognitive trait of the individual,”​^​1​​

Attentional Control

The main reason that working memory has such a limited capacity is that it must share the process of attention between information storage and maintenance.

“Effective time sharing of attention involves rapid, back-and-forth switching of attention from processing to maintenance (rehearsal). Memory items are lost when the processing requirements are such that the switching cannot occur or cannot occur in time to prevent loss of information.”​^​2​

Problems with attentional control can lead to high distractability,^​1​ poor goal achievement,^​3​ forgetfulness, poor time management, “reduced hindsight and forethought,” and “a reduction in the creation of anticipatory action toward future events.”^​4​ Additionally, “diminished control of attention also makes switching and updating difficult, causing loss of information.”^​2​

As to distractibility, people with low WM capacity find it much more difficult to ignore distractions than those with high WM capacity. It is thought that this is due to it taking longer to “disengag[e] attention from irrelevant information that captures their attention,” Thus, the connection between WM capacity and performance on complex cognitive tasks may be “the ability to efficiently deploy attentional control in overloading situations.”^​1​

We are only fully conscious of what we are currently focusing our attention on, and it is then that our thoughts and information can be processed, elaborated on,^​5​ used by other executive functions,^​3​ and encoded into long-term memory.^​6​ Being the focus of attention also gives the “critical information an accessibility advantage in the competition for access to working memory,” causing fewer distracting intrusions to come to mind and thus need more WM processing to be siphoned off from the main task in order to suppress.^​5​

“Its effects are akin to the way a flashlight illuminates the particular objects at which it is pointed and at the same time leaving all other things in the dark. As a consequence of sustained attention, access to working memory may be directed toward highly goal-relevant information and divorced from possible distractions,” thus “a great deal of information remains in an active but unattended state at the fringe of consciousness.”^​3​

Rehearsal (Information Maintenance)

As working memory representations “are vulnerable to distraction and interference […] when the perceptual input no longer is present, sustained attention along with a rehearsal process is crucial for maintaining the information in working memory.”​^​1​​  Rehearsal can be the vocal or sub-vocal (the voice in your head), effortful or automatic “repetition of information the individual is attempting to preserve long enough to complete a process or obtain a goal.”^​2​  ​

For example, if someone tells you something you need to write down, you may repeat the information over and over either out loud or “in your head”, until you are able to write it down. That is conscious rehearsal. Our brains can engage in automatic rehearsal just outside of our consciousness as well.^​2​​

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