Design, construction and validity and reliability Digital device Müller-Lyer Illusion

The purpose of this study was to design and build a device to measure and record the function of visual error and its adaptation time as well as to obtain the reliability of this tool.

By carrying out numerous investigations and according to articles and research, the prototype of the device was built by performing repeated tests. Due to the lack of a similar device in the country, the electrical circuit, the program, and the appearance of the device were changed several times during the manufacturing and measurement stages. Finally, based on the parts inside, the original sample was produced. The device includes a hardware section for performing various movement patterns by the subject and a software section for collecting and analyzing the obtained information.

To obtain the reliability of the device and to ensure its stability in repeated measurements, 50 students (35 males and 15 females) from Ferdowsi University were selected as available samples and tested in two stages with a 20-minutes interval.

The results were calculated using Pearson's correlation coefficient and Cronbach's alpha by SPSS20. The validity of the device is equal to 0.88 and its reliabilities in recording visual error and  the time of movement are 0/86 and 0/70, respectively.