This is a guest post by Joe Wilding, the CTO and Co-Founder of Boom Supersonic.
I was asked by someone recently: “How do you know so much about your field?” My short answer was, “I read a lot.” To that he replied: “Yeah, but how do you retain all of that knowledge?” I didn’t have a crisp answer at the time. But, as I have thought about that question since, I have come to realize I have developed a pattern over the years which has allowed me to retain much of the knowledge I have read.
While I have to admit this method requires additional effort, I’m personally convinced it’s required for long-term retention.
The method consists of two elements. The first is ensuring that you deeply understand the content when you first read the material. The second element is making the content sticky by refreshing your memory of it in a deliberate recurring process.
Deeply learning the topic
There are many ways to fully understand a topic when first exposed to it. If the topic is simple enough, the act of reading it, watching a video, or hearing it explained may be sufficient. For more complex topics, other tactics may be required. For me, they all come down to forming some sort of a model of the concept that makes sense to me. This model can be mental, or something that you actually sketch or turn into a diagram. Good books or other sources will do this for you, but not always.
I prefer to understand how the concept works based on the fundamental governing principles, whether that be physics, math, psychology, economics, etc. If math is involved, I do not gloss over the formulas. I pay attention to the inputs, the units, and the exponents on each variable. I try to deduce why each variable is there, and why others are not. I try to get a feel for how the answer would change based on different values of the inputs. If it is a topic i really want to understand I will enter the formula into a spreadsheet, plot it, and watch how the results change with different inputs. This “live feedback” method can increase your understanding tremendously and very quickly.
I also tend to formulate an understanding of the topic such that I can explain it to someone else. Often, I will literally do that: either out of necessity, or because I am typically surrounded by others who love to learn. It is very powerful to express a concept in your own words and to be prepared to answer questions or explain the parts that are not obvious.
Making it stick
A very unfortunate drawback of the human brain is that the knowledge it contains tends to fade over time. This is particularly true for concepts that are learned and then not accessed again before it is evolved into long-term memory. This means that all of the time and effort you put into learning a new topic could be lost if you don’t take action to make it stick.
This is less of an issue if the learned topic is something you will be using frequently for an extended period of time (such as in your daily job). However, much of what I read is a little more obscure, or something I will need only on infrequent occasions. To ensure this knowledge is not lost, I employ a method I read about many years ago called the Super-Memo Model, developed by the Polish researcher Piotr Woźniak.
The following graph shows how this works:
The graph shows that as a new topic is learned, but then not used again, the brain starts to lose that information on a decaying curve called the “curve of forgetting”. Nearly all of the knowledge on a topic can be lost in a few months. For example, try to remember something you might have heard on the news or read in a paper from a few months ago. If you didn’t have a direct connection to it, you probably can’t.
The happy side of this story is that if you refresh your memory of the topic, not only do you quickly get back to the 100% status, the rate of decay on the curve also decreases. If you can remember to do this three or four times, the decay curve becomes very flat and the information will be accessible nearly forever.
At this point you might be saying: “Great, I have to read everything four times if I really am going to learn it?!” Not at all. If you fully understand the topic the first time—in the way I talk about above—the refresh effort can be very quick. You just have to have a method of making the information quickly available and developing the discipline to actually go back and review it.
My favorite method for easy future accessibility is to take notes when I am first learning the topic. I summarize the key concepts, keep the sketch or diagram if there is one, hang onto the spreadsheet, and list all the references on where the knowledge came from. After that, it is just going back and rereading it a few times in the future. You could schedule these in your calendar, but I usually just keep the notes file on my desktop and then go back and reread it from time to time until I feel like it is fully committed to long term memory. At that point, I usually file it away in a folder for future reference.
There are other methods for reviewing material, including: reading other sources on the same topic, teaching it to others, or using the knowledge on a recurring basis. It doesn’t really matter what the method is. It is just important to refresh your memory routinely until you’ve really mastered it..
I’ll admit that this method requires effort, and I certainly don’t use it for everything I read. But if I have a topic that I really want to master long term, I have found that this method works every time.