Design, Fabrication, and Standardization of Visual Perception Error Measurement Test (Understanding the Size of the Length)

Visual perception error (VPE), especially in the measurement of physical quantities, is the most important aspect of perception error that has a significant impact on the dimensions of human life. This study aimed to design, fabricate, and standardize the visual perception error test (VPEMT) based on the domains of its distribution in Iranian society, in order to compare different individuals and groups in terms of their scores and means in this domain.

This descriptive-survey study was conducted using a number of cards with a two-part image of unequal lines, except for one case as a criterion, and was designed in (T) shape and tested on individuals. Finally, VPEMT consisted of 14 cards (Ta, Tb…Tn) with a difference of half a centimeter in the vertical line. A three-choice question was answered and implemented on 90 people of both genders (16-65 years), and the result was considered the base of the study. The statistical population included 15-45-year cases (mean age: 26 years) who lived in Ilam for 9 months. Eventually, a sample of 900 cases of both genders was randomly selected using the block-cluster sampling method and tested with VPEMT. (Ethic code: 1398.041.CER.B.UAI.RI)

The validity and reliability of the VPEMT were estimated by halving, within and between experts, and repeated tests (r=0.92 to r=0.98; and r=0.97, respectively). VPE has an almost normal distribution (mean=7.97, median=8, mode=9, dispersion=9, and range between 3 and 12) and diagnostic cut (Td/10) at 80% level, as well as the minimum and maximum error (1.5-6) cm in every 12 centimeters. Estimation of standard error showed the confidence intervals of the mean of the population from the mean of the group at the level of 0.05 (40±1 mm) (41> µ> 39).

Based on the research findings, it can be concluded that VPEMT, in showing the amount of VPE, in the population aged 15-45 years, based on two criteria (mean and reality) had very high validity and reliability. It can also be used diagnostically-selectively in different groups in this age range and research. Moreover, it has the potential to be upgraded to an accurate and automated electronic system or software for this purpose in such a way that the subject receives the amount of his/her perception error by pressing the desired key.