That’s the advice from a blogger/writer who has been studying and writing about how to achieve excellence. It’s mainly advice passed on from an expert piano player, but it has a certain intuitive appeal to it.
I think the idea comes from the perspective of “deliberate practice” and the idea that practicing that which is too easy (and therefore you experience a flow state during practice) does not lead to improvement.
Can we reconcile this with our idea that practice should maximize dopamine release by successfully overcoming challenges? I have described that idea previously as training so that you have as much success as possible while also realistically expecting that you might fail.
Perhaps we’d say that the flow state described by the pianist reflects a state of euphoria associated with performing so successfully that you cannot fail? That would separate the idea of a “flow state” from our idea of dopamine reward release — which is just a rough hypothesis anyway. Or perhaps the experience of the truly skilled expert is that they need to be challenged with more difficult training tasks to hit the maximal training reward level. That would account for the pianist’s experience seeing the “mediocre” practicing things that seem too easy as just reflecting the fact that they are less skilled and simpler training tasks are optimal for them. I wonder if anybody at the Music School here would have any insight on this kind of phenomenon.
In theory, we could test this with the SISL task by comparing sequence learning in conditions where we set the task speed to adaptively keep people at 75% correct or at ~100% correct (then test them under identical conditions).