One of the hallmarks of this illness is the fact that we can NOT multitask. One of Dr. Bell's tests was asking his patients random questions while clicking a pen. That pen clicking was just enough to distract the patient and make them unable to answer questions. It was one of his low tech tests for CFS/ME as no other patients would be affected by pen clicking as severely as PWME. So from his unscientific country doctor test we go to the scientific study that show this to be true:
Jan b Eyskens, MSc PT, DO, Pr Ph; Jo Nijs, PhD; Kristien Wouters; Greta Moorkens, MD, PhD
That paper basically says that when you distract a PWME while they are walking they stop walking as they can't walk and pay attention to something else at the same time. Personally I've known this since my illness started. On my severe days where I have trouble walking at all, the least little thing distracts me and I freeze in place until I can refocus on walking again. It is like the pen clicking test. The least little distraction causes me to stop walking and stand like a statue. My brain can't handle processing that much information at the same time. Walking is one of the more difficult tasks we do as humans which means that it takes a lot of brain power to perform the act of walking. PWME just don't have the processing capability to walk, talk and chew gum at the same time.