THE INFLUENCE OFF MÜLLER-LYER ILLUSION ON LENGTH ASSESSMENT: THE ALTERNATIVE WAY OF MEASURING THE STRENGTH OF THE ILLUSION

Abstract

Two experiment were conducted in order to investigate whether a Muller–Lyer's two forms ("fork" and "arrowhead") influence on the length assessment of a given line if they are used as a standard for measuring that line. The first experiment was consisted of reproductive tasks in which respondent should asses the length of a given line using lines with three types of endings (fork, arrowhead, vertical) as a measuring tool. The assessment of the test line length was expected to be dependent on the type of the endings used on measuring lines. The result shoved that the same given test line was assessed as consisted of smaller number of lines ended with fork endings and as consisted of greater number of lines ended with arrowhead endings in comparison to the number of lines with vertical endings. The second experiment consisted of productive tasks in which participant should produce the line consisted of the given number of connected lines with endings, the same endings from first experiment were used. Results showed that participants produced the test line of the same given length as consisted of smaller number of lines ended with fork endings and as consisted of greater number of  lines ended with arrowhead endings in comparison to the same number of used lines with vertical endings.