We all use what I call a “focus pool”. This concept is quite evident in particular to beginners. Say for example you are a beginner (maybe you are!). When first learning a scale, the thing you are focusing on the most is where the notes are. This more than likely requires 100% or your focus pool. That is what I consider to be a reading task and a left hand task. You’re using all of your focus pool just to find the proper notes. Maybe you’re not even using the proper fingering. After you get familiar with where the notes are, you only require around 70% of your focus pool to find the notes. Now, you can use the extra focus energy to think about the proper fingering. What about the right hand? Well, chances are in the beginning, you’re using all down picks and not really paying attention to the placement of your right hand. Once you get comfortable with the left hand details, you have more reserve in your focus pool to draw from again. You can add a new task such as a quicker tempo, alternate picking and palm muting.
These principles indeed apply to those of you that like to sing and play guitar. Once you are able to play all of your guitar parts as though you are on “auto-pilot”, that means you require only a small amount of your focus pool. Therefore you can use the remaining portion of your focus energy to sing your heart out.
So, consider your focus pool when practicing and use it wisely by adding one thing at a time. Once you get the basic idea on something new, sharpen up the details!