engleski

The negative Müller-Lyer illusion

Various theories have attempted to explain the cause of the ML illusion ; meanwhile, it seems that no theory has been able to grasp all aspects of this illusion. This research will prove the interesting phenomenon of the negative ML illusion, which may contribute to a new understanding of this illusion. Most geometric-optical illusions consist of a context which deforms the size or the shape of the middle portion of a stimulus. In the case of the ML illusion, fins create the context, and the central stimulus is the line in between them. In order to achieve a negative ML illusion it was necessary to temporarily disassociate the context from the central horizontal line. Exposure to fins was of a duration of 10 seconds, and exposure to lines was 100 milliseconds. In this instance a surprising phenomenon appeared, in which the effect of the illusion manifested itself in the opposite direction: The line which follow the convergent fins, and spatially was located between them, appeared longer ; and contrariwise, the line which followed the divergent fins appeared shorter. This is an effect opposite to what one receives in a case of classic ML illusion. An experiment with three conditions was carried out on a group of psychology students. The effect of the illusion was measured by the method of constant stimuli. The observed effect showed a significance in comparison to two control conditions – when compared to the assessment of line length without fins and when compared to the classic effect of the ML illusion. The effect may be explained by figural after-effect. This might mean that the negative ML illusion is conditioned by fatigue in angle selective cells. It is possible that the activation mechanism in normal conditions of sight also causes the classic ML illusion.

Müller-Lyer illusion; negative Müller-Lyer illusion; temporally disassociated presentation; figural after effect; angle selective cells

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