@Walter Hinteler,
Yes the reason for this is the visual input activates sensory inputs in the brain that cause blood-flow to be redirected to other areas of the body that become aroused and this shortage of blood flow decreases the necessary oxygen vital for cognitive functions and decision making. Therefore the female has the most advantage when the male is in this state of arousal, for negotiating her desires, since this state is the one that males are the most vulnerable. If you go back to read in the bible a whole city of men were killed because they had agreed to be circumcised, and because they were in this weakened state they were unable to defend themselves.
So men should take this as a warning an never do all of their critical thinking with their smaller head. Use the one between your shoulders for all important decision making and do not allow yourself to be confused between the function and use of each one.
some have called this error "thinking with your D_ _ _! There is a time and a place for each, do not get confused.