There is also some confusion 
because the scene appeared 
increasingly "normal" to 
Stratton. By "normal," I mean 
that Stratton became 
accustomed to the optical 
reinversion. He no longer paid 
much attention to its 
"peculiar" character. But 
"becoming accustomed" to 
something should not be 
confused with coming to 
perceive it differently. More 
telling tests of how an observer 
perceives things are possible, 
but Stratton did not attempt 
them. For example, suppose 
figures are flashed on a screen 
and the observer has to identify 
them. What would be the 
spontaneous response to a "W"? 
At the outset, it will look like 
an "M," but how will it look 
after prolonged wearing of the 
inverting lens device? If true 
egocentric adaptation occurs, 
the observer will report "W." In 
order to be sure that it is 
egocentric orientation that is 
being tested, one can have the 
observer lie in a supine 
position and view the letters 
overhead. Another test is to
require the supine observer 
to view an overhead spot 
moving in a horizontal plane. 
(The horizontal plane would
eliminate confusion about
gravity-based or 
environmentally defined 
orientation.) When the spot 
moves in the foot-to-head 
direction, will the observer see 
it move head-to-foot, as occurs 
at the outset of the experiment, 
or will he or she see it move 
veridically in the foot-to-head 
direction?