Despite the vertical appearing longer, the two lines are the
same length. This visual illusion is common to most humans. This
illusion happens in the real world, with a telephone pole or
tree appearing taller when vertical than when laying flat on
There are cultures where perpendicular lines are rare, such
as desert tribes who live in rounded huts without perpendicularly
angled tables and boxes and television sets. The people of these
societies are less likely to be fooled by the above illusion.
This illustrates that culture does influence one's visual
perceptions, even of such 'objective' things as lines and angles.
It is interesting that it is those experienced with perpendicular
lines that fall for this illusion. Most would assume it would
be the inexperienced that are more likely to be tricked.
(c) david rudd cycleback, cycleback.com
all rights reserved