Thank you!
So I thought, the problem was just dexterity, but no, another problem was within the brain. Read on

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I have an unusual intelligence profile. My verbal intelligence is a whole lot higher than non-verbal intelligence. Only 3% of the population exhibit such a difference - usually, people's intelligences are bulked up together more. They are not so spread out.
So every once in a while my conditioner stays in my hair. It is embarrassing. It happened again last week - I noticed it at work, to my severe embarrassment. Yet, I spend a long time washing the conditioner out of the hair.
Finally, I debugged the problem. My shower head is really low (as if for a child) and the water hits my neck. Standing for a long time does not help because the water keeps hitting my neck, without washing the conditioner off the top of my head. I have to squeeze myself under the shower head (in a very uncomfortable position, but what can I do?) for the water to hit the top of the head.
You'd think I have lived in this apartment for a month and have not figured out all its ins and outs. No... since Feb 2010!
I am clearly challenged when it comes to non-verbal intelligence.