Better Than Soup: Chunking

"Sloth love Chunk!" --Sloth

In a previous post, we talked about the severe constraints on working memory. Early estimates of the capacity of working memory started out around seven (plus or minus two) items. That translates into looking up a phone number in the phonebook (remember those?), walking over to the phone, and dialing the number. Unfortunately, seven seems like a very low number. In fact, later estimates put working-memory capacity around four items. Four items?! But that seems crazy low. Fortunately, there is a way to expand your working-memory capacity through a process called Chunking.

Does chunking really work? If it does work, what are the limits? How far can we stretch this strategy? 

Does Chunking Work?

How do we know that the brain is able to aggregate or "chunk" information? What is the evidence? To generate some evidence, this interesting study asked a couple of "volunteers" to memorize the position of chess pieces on a chessboard [1]. There were three types of participants. The first was a world-renowned chess master. The second was an intermediate player, but wasn't anywhere near the ability of the first player. The third person knew how to play chess, but was not ranked in any official capacity. The scientists showed them the configuration of a couple of chessboards that were in mid-game. The twist was that some boards were actual games, while the other boards had the same number of pieces, but they were randomly placed across the board. Before I tell you the outcome, what do you think they found? 

As you probably guessed, the chess master's memory for the position of the chess pieces was vastly superior to the intermediate and novice player's memory. What wasn't totally obvious, however, was how well they did relative to each other on the random boards. It turns out that they were all equally the same. This suggests that the chess master wasn't looking at individual pieces on the actual mid-game boards. Instead, he was aggregating the pieces into groups (e.g., a "castling" position). I love this study because it's an elegant demonstration of the process of chunking.

"Take It To the Limit" --The Eagles

The best answer to the question of limits comes from a study that attempted to train someone to expand his working-memory capacity [2]. Going into the experience, the person that was selected to endure the rigorous training regimen was a runner. That means he was well versed in thinking about numbers in terms of running times. He was able to chunk digits into running times. For example, 4:32:8 is an average time for a men's marathon. The runner worked for many training sessions by adding more and more complex retrieval structures. At the conclusion of the study, the participant was able to correctly recall 79 numbers. Impossible!

What does that mean for us ordinary mortals? First, this person wasn't special in any obvious way. That means that any one of us could also learn to memorize 79 digits if we were willing to put in the time and effort. Second, learning to memorize digits of numbers seemed to apply only to digits. In other words, the participant wasn't able to apply what he learned to memorize state capitals or other forms of information (e.g., letters). Finally, it also means that, although we have severe limits to our cognitive capacities, they can be overcome either by cognitive strategies and/or good, old-fashioned hard work (i.e., "deliberate practice"). 

A STEM Example

I'll be honest. When I took Physics in college, it was brutally difficult. Not because of the math (it was a non-calc version), it was hard because it seemed like each new concept arrived from out of the blue. Rotational kinematics seemed to have nothing to do with linear kinematics  Sure, the form of the equations seemed to have something in common, but they were largely taught as disconnected facts. 

Fast forward several years to my post-doc. I was blessed to work with a real physicist who pointed out to me that Physics is easy because you only need to know a few "first principles." From there, you can derive many other facts That hit me like a bolt of lighting. Once someone took the time to sit down with me and demonstrate the inner-connections, Physics didn't seem so hard. I don't want to trivialize education, especially for difficult topics, but the whole process can be made more simple (and perhaps fun?) if the material is presented as a sequence of ever-expanding chunks of information. 

Let's take velocity as an example. To build up to this advanced topic, it helps to start with our intuitive understanding of speed. Most of us have ridden in cars and talked about the measurement of speed in terms of "miles per hour." Once that gets translated into a symbolical representation (s = d/t), you can then expand it to include the concept of change (i.e., delta). Now the equation becomes s = Δd/Δt. Not a lot has changed, and that's a good thing because the student needs to see the equation, not as something new, but slightly expanded. Then you can expand the notion of the delta: Δd = d_final - d_initial. Plug this back into the equation, and you get a slightly more detailed expression. Again, each step is small and needs to be seen as a single chunk of information. 

Share and Enjoy! 

Dr. Bob

For More Information

[1] The chess study was conducted by a pair of researchers at Carnegie Mellon University (CMU) in the early 70s. The first author, Bill Chase, was my graduate-student advisor's late husband. I never had a chance to meet him, but he is a legend in the field of cognitive psychology. On the other hand, I did have the good fortune to take a course from the second author, Herb Simon. It was a fascinating course, and he gave probably the hardest final exam I have ever taken in my life. It had a single question: "Describe a computationally plausible model of cognition." We then had about three hours to provide an answer. 

Chase, W. G., & Simon, H. A. (1973). Perception in chess. Cognitive Psychology, 4, 55–81.

[2] Training someone to expand his working-memory capacity took 230 hours of practice! His training was conducted  by K. Anders Ericsson, who we will hear more about in subsequent posts. The original article can be found here. 

Ericsson, K. A. (1980). Acquisition of a memory skill. Science, 208(4448), 1181–1182.