My mother, at age 60+ was confined to an electric wheelchair for some
years, though her disability was purely physical. Her chair was of the
tricycle type with handlebars for steering, which had a lever under the
handles to switch the motor. letting go of the lever put the brakes on.
One day she reported having turned the chair over and falling in the
road (not a pleasant experience for an old lady). The cause was
difficult to find, until I realised that she had attempted to brake for
some small reason, and instinctively grabbed the "go" lever, which made
the chair go faster until she lost control. the cause of this action
became clear when I noticed the similarity with a bicycle handlebar,
where the under-levers are brakes (or at least, they were in the 30's
when mother last rode a bike!).
In effect this action lay dormant for about 40 years, re-appearing only
under pressure.
They say that "you never forget how to ride a bike"!
My mother was not stupid. You have been warned.
Keep up the good work
Mark Brunt
mb_at_cae.co.uk