It is a well known fact within pilot circles that the human brain cannot process data while engaging the use of primary focus. as soon as a pilot begins to process complicated data his primary focus switches off leaving his safety detection system to peripheral focus. This affect is not dissimilar to a very competent vehicle driver who can travel for many miles, thinking about a subject and finding himself unable to remember any part of the preceeding journey. Although he manages to navigate the roads in apparent safety, he has done so only by processing data which has entered his brain via his peripheral vision.
A simple test of the hypothesis is to ask any person to focus on your eyes and then ask the subject a modestly complex question such as, "What's the square root of 96." The subjects eyes will immediately break focus with your eyes as their brain attempts to process the data.
I hope this snippet of info will prove of interest.
Kind regards. David Peppiatt.