Information enters the brain through the senses—primarily, in most educational settings, through the eyes and ears. Where attention is directed, the information that's perceived moves into the working memory of the brain. To be learned, the information must be moved from working memory into long-term memory. This process is probably familiar to you. For example, when you hear someone's name for the first time, you probably remember the name as long as you're talking to the person. But unless you make a conscious effort to really learn the name—for example, by associating the person and the name with a particular image—you're likely to forget it later on.
Working memory is the main work area for thought, the conscious center of the brain. But its storage capacity is limited. Think of working memory as a small chalkboard. You start writing information on it, and it quickly fills up. Soon, you have to erase the board in order to put more information on it. In order to save the information you're erasing, you need to write it somewhere else—say, on a piece of paper, which is long-term memory. But you're working against time, so not everything on the chalkboard will be captured on the paper—some of it will be erased before you have time to copy it down.
Because of its limited capacity, working memory is the bottleneck in human information processing.
Most importantly, the limited capacity of working memory defines one key goal of effective teaching and training: to move knowledge and skills through working memory into permanent storage in long-term memory.
While in working memory, information must be used or practiced in some way or it will be lost. In cognitive psychology, the technical term used for this process is rehearsal. Rehearsal is what you do when you form a visual image or reorganize information in your mind so that you'll remember it later. When rehearsal is effective, it succeeds in capturing, or encoding, information in long-term memory. Unlike working memory, long-term memory has a large capacity and long duration. Once information is stored there, it will probably always be there. It becomes knowledge.
But storage in long-term memory isn't enough. When knowledge is needed, it must be retrieved from long-term memory and brought back into working memory for processing. So enabling people to retrieve information from long-term memory when it's needed is the final goal of teaching and training. This is called positive transfer.
The following illustration summarizes the flow of information from the senses through working memory into long-term memory and back into working memory through the processes of attention, encoding, rehearsal, and retrieval.
When teaching or training fails to take these processes into account, learning is disrupted. The amount of information people can process is essential to effective teaching or training. Indeed, bombarding learners with too much information at once, called cognitive overload, is one of the chief obstacles to learning. Creating instructional materials that overwhelm the learner's processing capacity will easily sabotage the training effort.
Imagine studying a chessboard where 24 pieces are arranged in a game in progress. Could you replicate the arrangement of the pieces after looking at the board for 10 seconds? How many times would you need to look at it, for a few seconds each time, before you could reproduce it from memory? A researcher named Herbert Simon asked groups of chess masters and chess novices to perform this task. Not surprisingly, the chess masters needed fewer exposures to the board—about four, on average—to reproduce the arrangement of pieces. The novices, on the other hand, needed several more exposures—as many as ten. What accounted for such differences between the abilities of the experts and the novices? Did the experts have better memory powers, or did their superior performance simply reflect their greater experience in the game of chess?
To distinguish between these alternatives, Simon repeated the experiment, but with the pieces placed randomly on the board rather than arranged in the form of a game in progress.
Had the masters indeed enjoyed superior powers of memory, their ability to reconstruct the board would have surpassed that of the novices in both phases of the experiment. Interestingly, however, the random arrangement of the pieces in the second phase significantly disrupted the masters in their attempts to reconstruct what they had seen, while the novices, for whom the arrangement of pieces had little or no meaning, were better off.
When challenged to "learn" the chessboards they were shown in Simon's experiment, the masters engaged in what's called a top-down analysis of each one: they looked for meaningful patterns in the arrangement of the pieces, to match the many such patterns they had stored in long-term memory. But when presented with meaningless information, in the form of randomly arranged pieces, their learning process was radically disrupted.
What does this tell us about working memory?
In a widely accepted formula for the capacity of working memory, researcher George Miller wrote that it can hold "seven plus or minus two chunks" of information.
But a chunk is a relative concept. In the first phase of Simon's chessboard experiment, the novices looking at the board saw 24 separate pieces of information—that is, 24 chunks. The masters saw patterns in the arrangement of the pieces, which enabled them to process what they saw in larger, but fewer, chunks. Clearly, the more expertise one has, the larger the chunks of information one can manage in working memory.
In some ways, this can work against the Lean Learner. Consider an experienced shop worker who has many years of experience in the old traditional batch process ways and in fact is considered to be quite the expert. When placed into a Lean Principles training exercise, the “expert” really does "think differently" from the way the novices think. They group chunks of the training information differently – and sometimes wrongly – trying to chunk the new information with cognitive associations. That's why experts in the traditional Batch ‘n Queue production methods sometimes become frustrated and tend to reject the Lean Principles. The new concepts just don’t feel right – they go against historical learned reason. Because they've been immersed in their area of expertise for years, they suddenly feel like the chess experts faced with random board patterns. Nothing makes sense. That is why the presentation of Lean Principles information must be made in small chunks that are simple for both expert and novices to grasp, and given time to digest the small chunks. Training developed by inexperienced trainers often produces cognitive overload in learners because the experts have failed to put themselves in the psychological shoes of the trainee.
To avoid cognitive overload, keep your training sessions simple and consistent.