摘要：The Müller-Lyer illusion is one of the most prominent geometrical-optical illusions that have been the subjectof experimental investigation throughout a century. Like most optical illusions the Müller-Lyer illusion is causedby an appropriate context - inward or outward fins that act in a specific manner. These fins either prolong or shortenthe central line placed between the fins. In this study, we manipulated the context by varying the presentation ofthe illusion parts, which led to the negative effect of Müller-Lyer illusion. Here we disassociated the context, i.e.,the fins that create the illusion, from the lines the length of which needed to be assessed. Firstly, the fins were presentedalone for 10 seconds, than the line would appear alone for 100 ms. In such situations the phenomenon ofillusion emerges in an opposite direction: the line that temporally succeeded the inward fins seemed longer, whilethe line succeeding the outward fins seemed shorter. An experiment with three experimental situations was carriedout. Twenty participants took part in the experiment, in three different experimental situations. The size of the illusionwas measured using the method of constant stimuli, which was also used to determine the point of subjectiveequality. The analysis confirmed the described effect which was found to be significant when compared to two othersituations: the control situation and the standard Müller-Lyer illusion situation. The negative Müller-Lyer illusionis possibly caused by a kind of after effect, which occurred by prolonged gazing at the fins and/or by fatigue of theappropriate selective angle sensitive cells. Such findings implicate that angle sensitive cells might be active in theemergence of the standard Müller-Lyer illusion.
