The first 5 seconds

So for the past few days one of the experiments I have been performing on myself is trying to see if it is possible to teach myself to think of two different things at the same time. Sounds crazy huh? We can teach our bodies and minds so many different things what makes it impossible to think that we cannot follow two different trains of thought at the same time? Wasn't there a time when you thought that algebra was impossible? Or maybe learning to juggle a ball with your foot like Ronaldinho. I have spent about 10 -15 minutes each day practicing for the past week. I have tried a few techniques such as trying to write from 1 to 10 with one hand and A-Z with the other, read and write at the same time, focus my attention on something such as a memory task (I use Memory Trainer which by the way also shows me how badly my brain functions the next day after a late night at the bar). So I video recorded myself using my laptop to see if I could find reasons why my brain quit focusing on both tasks. The interesting thing... I always lost my concentration after ~3-5 seconds repeatedly. When I was reading a book and writing the alphabet always around the letter F. Sometimes I would write the letter 'F' twice or sometimes I would skip 'E' or 'G' but the initial lose of focus always happened around this time. But for the first three seconds I could read coherently and write coherently. I wonder if the brain takes ~3 seconds to initially begin focusing on a task? or it is just the nature of the experiment? I wonder if other people experience the same thing. Try it and let me know!