Effects of Shape, Size, and Chromaticity of Stimuli on Estimated Size in Normally Sighted, Severely Myopic, and Visually Impaired Students

Abstract

Effects of shape, size, and chromaticity of stimuli on participants' errors when estimating the size of simultaneously presented standard and comparison stimuli were examined. 48 Taiwanese college students ages 20 to 24 years old (M = 22.3, SD = 1.3) participated. Analysis showed that the error for estimated size was significantly greater for those in the low-vision group than for those in the normal-vision and severe-myopia groups. The errors were significantly greater with green and blue stimuli than with red stimuli. Circular stimuli produced smaller mean errors than did square stimuli. The actual size of the standard stimulus significantly affected the error for estimated size. Errors for estimations using smaller sizes were significantly higher than when the sizes were larger. Implications of the results for graphics-based interface design, particularly when taking account of visually impaired users, are discussed.

The perceptual organization of space is preserved even if based on a different (quantity of) visual input

“…Subjects can estimate surface properties using measurements such as textures, the average brightness, and contrast between light and shadow parts of the image [9]. In our daily life, the perceived size of objects plays an important role in helping people to move in the natural environment through ongoing evaluation of the sizes of objects and spaces [10]. When an object is presented in a visual angle of about 2° or less we tend to overestimate the size of objects at angles greater than 2° we have a slight tendency to underestimate the size.…”

Object distance scaling in real space is preserved in low vision subjects

“…In our daily life, the perceived size of objects plays an important role in helping people to move in the natural environment through ongoing evaluation of the sizes of objects and spaces [10]. When an object is presented in a visual angle of about 2° or less we tend to overestimate the size of objects at angles greater than 2° we have a slight tendency to underestimate the size.…”

“…According to those authors, subjects with low vision have increased wrong judgments on the estimated size than people with normal vision. The chromaticity is a factor that also affects the estimated sizes, in which the more saturated the color, the closer it seems while more neutral colors seem more distant [10].…”