A particular retinal image, no matter how static does not evince uniform interpretations among different individuals and even to an individual. This particular phenomenon is called visual ambiguity. Carpentier and Mainguenaud (2004) define it as such representations that correspond to various interpretations. These various interpretations, however, do not occur simultaneously to an individual. At a certain time, an individual’s perception corresponds only to one of all the possible interpretations.
This limitation is the brain’s attempt to organize information so as to prevent chaos as well as to minimize uncertainties (Purves and Andrews, 1997) Visual ambiguities are resolved when viewers tend to analyze the elements by attempting to establish a balance (Graphic Design 2—Visual Perception, n. d. ) using available information such as concurrent objects in the scene, interpretive cues and even past experiences (Wade and Stanton, 2001). An individual accumulates through experience different associations elicited by retinal images and eventually forms assumptions based on these associations (Purves and Andrews, 1997).
Future available information and experiences are usually dependent on these existing assumptions which would provide a context that can be used to transform an ambiguous scene into a meaningful perception (Payne, Shimizu and Jacoby, 2005). How the mind resolves visual ambiguities is revealed using the Mueller-Lyer illusion. This illusion shows two parallel lines, with arrowheads at all four endpoints. One line has both of its arrowheads pointing towards it (line 1), while the arrowheads of the other point away from it (line 2).
What is curious about this is that although both lines have exactly the same length, line 1 is usually perceived to be longer than the other. Payne, Shimizu and Jacoby (2005) explain this as the visual system’s way of compensating for the difference in apparent sizes of objects depending on their distance from the viewer. According to them, because line 1 had concave angles at the top, it has an effect of receding away from the viewer while line 2 when viewed in isolation appears to be nearer.
This last sentence is almost general knowledge and as such, it is a general assumption. These assumptions or expected differences in size trigger the mind to compensate by interpreting line 1 as longer than line 2 (Payne, Shimizu and Jacoby, 2005).
References
Carpenter, C. and Mainguenaud, M. (2004). Classifying Ambiguities ina Visual Spatial Language. GeoInformatica, 6(3): 285-316. Graphic Design 2—Visual Perception. (n. d. ) CSUSM. Retrieved 03 December 2008 from http://www2. csusm.edu/iits/trc/training/lessons/graphicDesign/d2Perception/2_design_perception. htm. Payne, B. , Shimizu, Y. and Jacoby, L. (2005). Mental control and visual illusions: Toward explaining race-biased weapon misidentifications. Journal of Experimental and Social Psychology, 41, 36-47. Purves, D. and Andrews, T. (1997). The perception of transparent three-dimensional objects. Proc. Natl. Acad. Sci, 94, 6517-6522. Wade, N. and Swantson, M. (2001). Visual Perception: An Introduction. USA: Psychology Press.