The Muller-lyer liiusion is suppose to trick your brain by thinking that the line is bigger or longer than the one in front. This what is really happening, Your brain sees the liiusion and thinks that the back is longer because it looks farther away.It really is the same height or length and to show this we would have to able to turn it see this at an different angle.
Gibson Vs. Gregory - Perception." Bryony Sheppard Psychology. N.p., 22 Sept. 2013. Web. 17 Mar. 2015.