Monocular versus Binocular Vision of the
Distorted Ames Room Illusion

Anthony Cuttitta, Aaron Destadio, and Dustin Gary, Alma College, 06aacutt@alma.edu, 06amdest@alma.edu, 09dcgary@alma.edu

Prior studies have concluded differences in monocular and binocular vision. Gehringer and Engel(1986) and Pilewski and Martin(1991) found that both binocular and monocular vision created an Ames room illusory effect. The purpose of this study was to observe monocular and binocular differences when viewing the Ames room illusion.

METHODS
The Ames room illusion was re-created using luminous paint; the paint outlined the trapezoidal far wall of the Ames room re-creating the illusory effect. The smaller end of the trapezoidal wall was tilted toward the observer to a point at which the trapezoid was viewed as a rectangle. There were two circles, 200 mm in diameter, also outlined in luminous paint. The circles were placed on the far left of the wall and the far right of the wall. Subjects viewed this in darkness to ensure that this wall was the only visual stimulus. Initially, subjects estimated the diameter in mm of the right(closer) circle when given the true diameter of the left circle with one eye. Next, subjects performed the same estimation using binocular vision.

RESULTS
Results showed the Ames room effect to be statistically significant (p<.001) with both monocular and binocular vision, though the effect was markedly stronger with monocular vision. This is shown in the graph below.


Figure 1. Size Estimation vs. Vision Type. This graph represents mean estimation values for the two vision types and also gives the actual size of the circles. Mean values and Y-axis values are in millimeters.

DISCUSSION
The results show that viewing the Ames room with binocular vision does maintain the Ames room illusion; however the illusion effect is weaker than that with monocular vision. Results also proved the trapezoidal far wall of the Ames room to be the only necessary wall for an Ames room effect; the other walls function as restrictions for visual cues. Darkness was used as a restriction of visual cues in this experiment.

REFERENCES
Gehringer, Engel. (1986) Effect of ecological viewing condtions on the ames' distorted room illusion. Journal of Experimental Psychology, 12, 181-185.

Pilewski, Martin. (1991) Effects of monocular versus binocular viewing in the ames distorted-room illusion. Perceptual and Motor Skills, 72, 306.

Beagley, W, (2006) Personal Communication. Alma College.

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