The Term: Desirable Difficulties
During strenuous exercise, such as weightlifting, micro-tears occur in your muscles. Like a coastal town building stronger sea defences after a flood, the body recognises that these muscles may be subject to damage again, and rebuilds the fibres with additional strength. In my lessons I say “The brain is like a muscle” quite often. Of course it’s not actually a muscle but it does need to be fed, watered and rested. Also like a muscle: by making it work harder it will get stronger. The psychologists Elizabeth and Robert Bjork have termed this phenomenon “desirable difficulty”.
If someone asked you to choose between reading a page of text in a clear font, or a slightly out of focus one, it’s obvious what you would pick. Strangely enough though, research has shown that readers retain information better when it’s a little difficult to decipher. Similarly, when some letters are removed from words, thus reducing reading speed, people recall the content better when tested later on. What is going on here? Well, as the brain is forced to focus and engage more with the content, more robust memories are created.
Of course, if the text were nearly illegible, then the difficulty would be undesirable. Like a weightlifter trying to lift a bus: if there is no movement, there is no exercise. So as tutors we have to make sure the tasks we set are tough but doable, with some effort.
So, should we supply all of students with blurry texts?
There are many ways to make them work harder for the information we want them to retain: We can get them to probe more deeply into the content through appropriate questions, get them to teach it to us, or ask them questions on a topic before we’ve taught it. The key thing is to make sure they are stretched – to put them in the stretch zone.