Muller Lyer Final Lab Report Essay

1684 Words Oct 10th, 2014 7 Pages
The impact of global and local processing on the perceived adjustment error in the Muller-Lyer illusion. A test of Day’s (1989) Conflicting Cues Theory.

Abstract
The nature of visual illusions is hotly debated in the scientific literature, in search of a theory to explain how perceptual distortions arise upon daily interactions with the world. The present study provides the first direct test of Day’s (1989) Conflicting Cues theory to account for the Muller-Lyer illusion. Perceptual compromise was investigated, by measuring the impact of global and local processing on perceptions of size, as modulated by Navon stimuli. Following exposure to global, local or neutral cues, participants adjusted
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However this notion of regression towards the mean, has not withstood experimental manipulation of the fins-out Muller-Lyer figure (Day, 1989). Confusion theory on the other hand (Sekuler & Erlebacher, 1971), stipulates that the illusion is determined by the inter-tip distance between the arrowheads, where the larger distance of the fins-out arrangement and the smaller distance of the fins-in arrangement results in perceptual expansion and contraction, respectively .Like Assimilation theory, Confusion theory fails to accurately predict the size of the constant error for the experimental manipulation of the fins-out arrangement (Sekuler & Erlebacher, 1971). The inability of a single theory to account for all forms of the illusion has led some researchers to conceptualize Muller-Lyer as two distinct illusions. Nevertheless, echoing the common theme of perceptual averaging, Day (1989) proposed the Conflicting Cues theory to account for Muller-Lyer as a unitary phenomenon. Herein, the conflict between two cues for size, namely the actual line length and overall length of the figure, is resolved via a compromise between local and global processing in the brain. The present study investigates the relevance of perceptual compromise to the Muller-Lyer illusion.

The role of global and local processing has previously been investigated with the use of Navon stimuli (Navon, 1977). Herein, large letters are comprised of smaller letter elements. Indeed, studies

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