Kuo-Chen Huang

Visual search performance on an lcd monitor: effects of color combination of figure and icon background, shape of icon, and line width of icon border.

This study investigated the effects of color combinations for the figure/icon background, icon shape, and line width of the icon border on visual search performance on a liquid crystal display screen. In a circular stimulus array, subjects had to search for a target item which had a diameter of 20 cm and included one target and 19 distractors. Analysis showed that the icon shape significantly affected search performance. The correct response time was significantly shorter for circular icons than for triangular icons, for icon borders with a line width of 3 pixels than for 1 or 2 pixels, and for 2 pixels than for 1 pixel. The color combination also significantly affected the visual search performance: white/yellow, white/blue, black-red, and black/yellow color combinations for the figure/icon background had shorter correct response times compared to yellow/blue, red/green, yellow/green, and blue/red. However, no effects were found for the line width of the icon border or the icon shape on the error rate. Results have implications for graphics-based design of interfaces, such as for mobile phones, Web sites, and PDAs, as well as complex industrial processes.

Effects of color combination and ambient illumination on visual perception time with TFT-LCD.

An empirical study was carried out to examine the effects of color combination and ambient illumination on visual perception time using TFT-LCD. The effect of color combination was broken down into two subfactors, luminance contrast ratio and chromaticity contrast. Analysis indicated that the luminance contrast ratio and ambient illumination had significant, though small effects on visual perception. Visual perception time was better at high luminance contrast ratio than at low luminance contrast ratio. Visual perception time under normal ambient illumination was better than at other ambient illumination levels, although the stimulus color had a confounding effect on visual perception time. In general, visual perception time was better for the primary colors than the middle-point colors. Based on the results, normal ambient illumination level and high luminance contrast ratio seemed to be the optimal choice for design of workplace with video display terminals TFT-LCD.

Effects of colored light, color of comparison stimulus, and illumination on error in perceived depth with binocular and monocular viewing.

Two experiments assessed the effects of colored light, color of a comparison stimulus, and illumination on error in perceived depth with binocular and monocular vision. Exp. 1 assessed effects of colored light, color of comparison stimulus, and source of depth cues on error in perceived depth. A total of 29 women and 19 men, Taiwanese college or graduate students ages 20 to 30 years (M = 24.0, SD = 2.5) participated; they were randomly divided into five groups, each being assigned to one of five possible colored light conditions. Analyses showed color of the comparison stimulus significantly affected the error in perceived depth, as this error was significantly greater for a red comparison stimulus than for blue and yellow comparison stimuli. Colored light significantly affected error in perceived depth since error under white and yellow light was significantly less than that under green light. Moreover, error in perceived depth under white light was significantly less than that under blue light but not sensitive to white, yellow, and red light. Error in perceived depth for binocular viewing was significantly less than that for monocular viewing but not sex. In Exp. 2, the effect of illumination on error in perceived depth was explored with 21 women and 15 men, Taiwanese college students with a mean age of 19.8 yr. (SD = 1.1). Analysis indicated that illumination significantly affected error in perceived depth, as error for a 40-W condition was significantly greater than under 20- and 60-W conditions, although the latter were not different.

Numeral Size, Spacing between Targets, and Exposure Time in Discrimination by Elderly People Using an LCD Monitor

The present study investigated the effects of numeral size, spacing between targets, and exposure time on the discrimination performance by elderly and younger people using a liquid crystal display screen. Analysis showed size of numerals significantly affected discrimination, which increased with increasing numeral size. Spacing between targets also had a significant effect on discrimination, i.e., the larger the space between numerals, the better their discrimination. When the spacing between numerals increased to 4 or 5 points, however, discrimination did not increase beyond that for 3-point spacing. Although performance increased with increasing exposure time, the difference in discrimination at an exposure time of 0.8 vs 1.0 sec. was not significant. The accuracy by the elderly group was less than that by younger subjects.

Effects of numbers of strokes on chinese character recognition during a normal reading condition

Two experiments investigated recognition during a normal reading condition of Chinese characters which had varied numbers of strokes. In Exp. 1 the minimal legible character size necessary for attaining 95% recognition accuracy for various Chinese characters was empirically determined. The number of strokes comprising the characters ranged from 3 to 27. The results of a normal reading condition indicated that characters with more strokes had to be larger. In Exp. 2, recognition error rate and reading time measured in seconds were investigated for one Chinese character string composed of characters of minimally legible size versus conventional equal-size characters presented in a normal reading condition. Recognition error rates for the minimally legible size conditions were lower than those for the conventional size conditions. The reading times for the former were shorter. These results should provide a valuable reference for designing informational formats, literacy teaching, and the study of simplifying Chinese characters.

Icon Flickering, Flicker Rate, and Color Combinations of an Icon's Symbol/Background in Visual Search Performance

The effects of color combinations of an icons symbol/background and components of flicker and flicker rate on visual search performance on a liquid crystal display screen were investigated with 39 subjects who searched for a target icon in a circular stimulus array (diameter = 20 cm) including one target and 19 distractors. Analysis showed that the icons symbol/background color significantly affected search time. The search times for icons with black/red and white/blue were significantly shorter than for white/yellow, black/yellow, and black/blue. Flickering of different components of the icon significantly affected the search time. Search time for an icons border flickering was shorter than for an icon symbol flickering; search for flicker rates of 3 and 5 Hz was shorter than that for 1 Hz. For icons symbol/background color combinations, search error rate for black/blue was greater than for black/red and white/blue combinations, and the error rate for an icons border flickering was lower than for an icons symbol flickering. Interactions affected search time and error rate. Results are applicable to design of graphic user interfaces.

Measurement of Discrimination of Separation in Elderly Persons Using a Liquid-Crystal Display and Grating Method

This study analyzed psychophysical data from younger and elderly people on the influence of spacing between vertical lines, exposure time, and number of vertical lines in a stimulus for visual performance. A total of 50 elderly people and 31 graduate students participated in the experiment. Nine levels of spacing between lines (3, 6, 9, 12, 15, 18, 21, 24, and 29 points), three exposure times (0.2, 0.6, and 1.0 sec.), and five sets of numbers of lines (4, 5, 6, 7, and 8) were manipulated. Analysis showed enhanced spacing between lines and exposure time improved discrimination of separation. However, although performance on discrimination of separation increased as spacing between lines increased up to 21 points, it was degraded at higher values. A positive effect of number of lines on discrimination of separation was also observed, and performance increased as the number of lines decreased. The effect of age group, i.e., elderly versus younger, on performance was significant. The accuracy of the younger was greater than that for the elderly group. Moreover, three interactive two-way effects were found: group × spacing between lines, number of lines × spacing between lines, and number of lines × exposure time. The present findings could be used as a practical reference in the design of instrument displays in which the operator has to consider the scale and markings on a dial, especially if the display is operated in an emergency or is manipulated by elderly people.

Effects of Cane Length and Diameter and Judgment Type on the Constant Error Ratio for Estimated Height in Blindfolded, Visually Impaired, and Sighted Participants

The purpose of this study was to assess the ability of blindfolded, visually impaired, and sighted individuals to estimate object height as a function of cane length, cane diameter, and judgment type. 48 undergraduate students (ages 20 to 23 years) were recruited to participate in the study. Participants were divided into low-vision, severely myopic, and normal-vision groups. Five stimulus heights were explored with three cane lengths, varying cane diameters, and judgment types. The participants were asked to estimate the stimulus height with or without reference to a standard block. Results showed that the constant error ratio for estimated height improved with decreasing cane length and comparative judgment. The findings were unclear regarding the effect of cane length on haptic perception of height. Implications were discussed for designing environments, such as stair heights, chairs, the magnitude of apertures, etc., for visually impaired individuals.

Effects of colored lights, spacing between stimuli, and viewing distance on error in a depth-matching task.

A previous study indicated that color of a comparison stimulus, colored light, and illumination significantly affected the error in perceived depth with binocular and monocular vision. Here, the effects of spacing between standard and comparison stimuli, viewing distance, and five colored lights were investigated. 32 Taiwanese university students in five groups were assigned to one of five colored light conditions. Spacing between comparison and standard stimuli significantly affected error in a depth-matching task. Errors increased with increased spacing. Colored light also had a significant effect; error rate in the depth-matching task under the green light condition was significantly greater than the rates under the white, yellow, and red light conditions, but the difference in error rates between blue and green and among the white, yellow, and red light conditions were not significant. The error rate at a viewing distance of 110 cm was significantly less than errors under 70- and 150-cm conditions. In addition, a two-way interaction effect was detected: viewing distance with spacing between standard and comparison stimuli.

Effects of luminance ratio in a liquid-crystal display on discrimination of separation by elderly people.

In a 2006 study the influence of spacing between vertical lines, exposure time, and number of vertical lines on visual performance was identified. The present study further explored the effects of luminance ratio on discrimination of separation. Analysis showed the luminance ratio of target vertical lines affected the visual performance of both younger and elderly people. The luminance ratio was greater, as was accuracy; however, accuracy might not become greater when the luminance ratio was too high. Further, the effect of the number of vertical lines on accuracy was significant, as was consistent with the 2006 study. Two interactive two-way effects were found, group × luminance ratio and luminance ratio × number of vertical lines.