After-effects of TFT-LCD display polarity and display colour on the detection of low-contrast objects

Effects of background colour, polarity, and saturation on digital icon status recognition and visual search performance

Visual design form is an important factor affecting users' cognition of icons, which plays an important role in visual search and the perception of the status shown by icons. In the graphical user interface, the icon colour is regularly used to indicate the running state of a function. The aim of this study was to investigate the effects of icon colour features on user perception and visual search performance under different background colours. There were three independent variables in the study, including background colour (white and black), icon polarity (positive and negative), and icon saturation (60, 80, and 100%). Thirty-one participants were recruited for the experiment. Task performance and eye movement results indicated that white background as well as positive polarity and 80% saturation icons brought the best performances. The findings of this study provide useful guidelines for designing more efficient and user-friendly icons and interfaces in the future.Practitioner summary: This study was to investigate the effects of icon colour features (polarity and saturation) on user perception and visual search performance under different colour backgrounds. Task performance and eye movement results indicated that white background as well as positive polarity and 80% saturation icons brought the best performances.

Dark mode vogue: Do light-on-dark displays have measurable benefits to users?

This work investigates the effect of display polarity on cognitive load, using eye-tracking and subjective measures, and emotional reactions to assess whether the popularity of negative polarity displays is related to affective qualities or true physiological benefits. Younger and older adults tested positive and negative polarities under bright and dim environments for writing and search tasks. Eye-tracking results showed higher cognitive load using negative polarity, reflected in increased search time and pupil diameter for older adults in a bright environment and younger adults in a dim environment. For older adults, mental effort scores were higher using negative polarity for the search task in a bright environment. This group reported more positive emotions using positive polarity, while younger adults expressed more interest in negative polarity. These results suggest that older adults use positive polarity to avoid mental fatigue, while younger adults use negative polarity in a dim environment for aesthetic reasons. Practitioner summary: The effects of negative polarity on cognitive load and users' preferences are often unclear. Eye-tracking and subjective data reveals that negative polarity displays elicit higher cognitive load for older adults in a bright environment and younger adults in a dim environment, suggesting older adults prioritise reduced fatigue while younger adults prioritise the feel of the interface.

The influence of brightness combinations and background colour on legibility and subjective preference under negative polarity

This study explores the influence of colour combinations on legibility and aesthetic feelings for the currently popular negative polarity interface design. Legibility was measured in two different ways in two tasks: time threshold (Task I) and a 9-point subjective rating (Task II). In Task I, we combined an adaptive program to measure 37 participants' recognition thresholds and online pseudo-word recognition tasks; in Task II, 44 participants' subjective preferences were measured using a scale. We found that higher brightness contrasts led to better legibility; different background colours with identical brightness and saturation did not cause significant differences; brighter texts produced better subjective preference for aesthetic appearance, legibility, and visual comfort; and different background colours had no significant effect on subjective preference. These findings have implications for digital interface design. Practitioner summary: In display design under negative polarity, experimental results show that higher brightness contrast leads to higher legibility, while background colour has no such significant effect; background brightness and hue have no significant effect on subjective preference, but text brightness and background colour have significant interaction effect on subjective preference. Abbreviations: OLED: organic light-emitting diode; LCD: liquid crystal display; ANOVA: analysis of variance; VDT: visual displsy terminal; CET-4: college english test band 4; ISO: International Organization for Standardization; HSB: hues saturation brightness.

Effects of ambient illumination, contrast polarity, and letter size on text legibility under glance-like reading

Recent research on the legibility of digital displays has demonstrated a "positive polarity advantage", in which black-on-white text configurations are more legible than their negative polarity, white-on-black counterparts. Existing research in this area suggests that the positive polarity advantage stems from the brighter illumination emitted by positive polarity displays, as opposed to the darker backgrounds of negative polarity displays. In the present study, legibility thresholds were measured under glance-like reading conditions using a lexical decision paradigm, testing two type sizes, display polarities, and ambient illuminations (near-dark and daylight-like). Results indicate that legibility thresholds, quantified as the amount of time needed to read a word accurately, were highest for the negative polarity configurations under dark ambient illumination, indicated worse performance. Conversely, the positive polarity conditions under dark ambient illumination and all conditions under bright illumination demonstrated significantly reduced thresholds, indicating greater legibility. These results are consistent with the hypothesis that the "positive polarity advantage" arises because brighter illumination produces pupillary contraction that reduces optical aberrations as light enters the eye. These results have implications for the design of automotive interfaces and other scenarios in which an interface must be optimized for glance-like reading under variations in ambient lighting conditions.

Reading from computer screen versus reading from paper: does it still make a difference?

Four experiments were conducted to test whether recent developments in display technology would suffice to eliminate the well-known disadvantages in reading from screen as compared with paper. Proofreading speed and performance were equal for a TFT-LCD and a paper display, but there were more symptoms of eyestrain in the screen condition accompanied by a strong preference for paper (Experiment 1). These results were replicated using a longer reading duration (Experiment 2). Additional experiments were conducted to test hypotheses about the reasons for the higher amount of eyestrain associated with reading from screen. Reduced screen luminance did not change the pattern of results (Experiment 3), but positioning both displays in equal inclination angles eliminated the differences in eyestrain symptoms and increased proofreading speed in the screen condition (Experiment 4). A paper-like positioning of TFT-LCDs seems to enable unimpaired reading without evidence of increased physical strain. Practitioner Summary: Given the developments in screen technology, a re-assessment of the differences in proofreading speed and performance, well-being, and preference between computer screen and paper was conducted. State-of-the-art TFT-LCDs enable unimpaired reading, but a book-like positioning of screens seems necessary to minimise eyestrain symptoms.

Smaller pupil size and better proofreading performance with positive than with negative polarity displays

The 'positive polarity advantage' describes the fact that reading performance is better for dark text on light background (positive polarity) than for light text on dark background (negative polarity). We investigated the underlying mechanism by assessing pupil size and proofreading performance when reading positive and negative polarity texts. In particular, we tested the display luminance hypothesis which postulates that the typically greater brightness of positive compared to negative polarity displays leads to smaller pupil sizes and, hence, a sharper retinal image and better perception of detail. Indeed, pupil sizes were smaller and proofreading performance was better with positive than with negative polarity displays. The results are compatible with the hypothesis that the positive polarity advantage is an effect of display luminance. Limitations of the study are being discussed.

Positive display polarity is particularly advantageous for small character sizes: implications for display design

OBJECTIVE

To test the display luminance hypothesis of the positive polarity advantage and gain insights for display design, the joint effects of display polarity and character size were assessed with a proofreading task

BACKGROUND

Studies have shown that dark characters on light background (positive polarity) lead to better legibility than do light characters on dark background (negative polarity), presumably due to the typically higher display luminance of positive polarity presentations.

METHOD

Participants performed a proofreading task with black text on white background or white text on black background. Texts were presented in four character sizes (8, 10, 12, and 14 pt; corresponding to 0.22 degrees, 0.25 degrees, 0.31 degrees, and 0.34 degrees of vertical visual angle).

RESULTS

A positive polarity advantage was observed in proofreading performance. Importantly, the positive polarity advantage linearly increased with decreasing character size.

CONCLUSION

The findings are in line with the assumption that the typically higher luminance of positive polarity displays leads to an improved perception of detail. Application: The implications seem important for the design of text on such displays as those of computers, automotive control and entertainment systems, and smartphones that are increasingly used for the consumption of text-based media and communication. The sizes of these displays are limited, and it is tempting to use small font sizes to convey as much information as possible. Especially with small font sizes, negative polarity displays should be avoided.

Effect of display polarity and luminance contrast on visual lobe shape characteristics

The effect of display polarity and luminance contrast on visual lobe (effective visual field) shape characteristics was studied using three levels of luminance contrast with combinations of positive and negative polarities. The binocular effective visual field for a detection task, with a peripherally presented target (V) embedded in a homogeneous competing background (Xs), was mapped on 24 imaginary axes passing through the fixation point. The results showed that visual lobes mapped using positive polarity were statistically larger in area, rounder and more regular in shape than those for negative polarity. The medium contrast condition lobes were more symmetric and regular than low contrast condition lobes, and lobe area and perimeter increased with increasing luminance contrast ratio. Under the interaction of positive polarity and high luminance contrast, visual lobes were found to be larger, smoother and rounder. The high level of luminance and contrast however resulted in a higher degree of visual discomfort. The results indicated that positive polarity and contrast of medium (26:1) to high (41:1) levels are possible display settings for better visual lobe characteristics and better anticipated search performance. Practitioner Summary: The effect of display polarity and luminance contrast on visual lobe shape characteristics was examined with uniform stimulus materials in this study. The results help to identify the optimum display settings for luminance contrast and display polarity to enhance lobe shape characteristics and hence search performance in industrial inspection tasks.