Psychology

The Mller-Lyer illusion was invented--by German psychologist and sociologist Franz Carl Mller-Lyer in 1889. He published fifteen different versions of his namesake in the German magazine Zeitschrift fr Psychologie. This research exhibits how lines can seem to be indistinct due to their background. It examined the consequence of line orientation and arrowhead angle on a subjects capability to distinguish line length, thereby testing the Mller-Lyer illusion.

Methods
The subjects were 10 random people all of them females aged 18-22. We used a magnitude estimation procedure to methodically display the Muller-Lyer illusion along with pit the Size- and Shape-constancy-based accounts of the illusion against each other. The two lines are attached to obtuse and acute angles so that they are lengthened and shortened. They may not be lengthened and shortened as much as with the standard Muller-Lyer stimuli because there are only two tabs per line. It needs to be lengthened and shortened at least to some extent. Method of constant stimuli was used where Muller-Lyer stimuli were presented with half of their tabs missing to the participants.

Results
Trial 1 included keeping the stimuli at length 3. A single line was observed with a value of 2.98, where as a Double ML acute having 8 tabs with acute angleswas observed with a value of 2.9, also Double ML obtuse having 8 tabs with obtuse angleswas seen with a value of 3.14. We measured Double Exp-Acute having 2 tabs one at each end which were acute, that gave a value of 2.93, where as Double Exp-Obtuse having 2 tabs one at each end which were obtuse, gave a value of 3.08.

The second trial i.e. Trial 2 had the stimuli kept at a different length which was 4. Here the values varied to a great extent. Single showed 4.06, Double ML acute had 3.98, Double ML-Obtuse displayed 4.22, Double Exp-Acute had 4.01 and Double Exp-Obtuse 4.16.

For the next trial we shifted the stimuli kept to a length of 6. The variations that we saw are listed as follows, Single 6.05, Double ML acute had 5.97, Double ML-Obtuse displayed 6.21, Double Exp-Acute had 6 and Double Exp-Obtuse 6.15.

The last trial had the stimuli kept at a length of 7. Survey showed Single having 6.97, Double ML acute had 6.89, Double ML-Obtuse displayed 7.13, Double Exp-Acute had 6.92 and Double Exp-Obtuse 7.07.

The mean averages were 5.015, 4.935, 5.175, 4.965 and 5.115. The differences of (Single and Double ML Acute) a, (Single and Double ML Obtuse) b, (Single and Double Exp-Acute) c, (Single and Double Exp-Obtuse) d, yielded 0.08, -0.16, 0.05 and -0.8 respectively.

We then went ahead and found differences between a and b, c and d which gave us 0.24 and 0.15.

Discussions
The illusion did not occur for the lines and hence the Size-constancy-based explanation is correct and the illusion occurred proving that the Shape-constancy-based explanation is correct. The Mller-Lyer illusion is the natural corollary of the edifice of the vertebrate eye, retina and visual processing system. Due to flaws in the vertebrate eye and retina combined with subsequent processing in the system by ever growing amenable fields, the visual information becomes less and less precise with respect to exact location and size.

Causes for Shape-constancy-based explanation When the brain compares lines from these two situations to each other, it reduces the size of the line with the inward sloping tails (the corner of the building) because it thinks this line is closer to us. It increases the size of the line with the outward sloping tails (the corner of the room) because it thinks this line is further away. This makes the line with the outward facing tails look longer.

Causes for Size-constancy-based explanation The viewer unconsciously invokes the relationship Perceived Size  Retinal Image Size X Perceived Distance and thinks reflexively that these two lines are causing retinal images of the same size, yet the obtuse-tabbed line appears farther away leading to the illusion that the obtuse-tabbed line must be longer.