Digital Display Preference of Electronic Gadgets for Visual Comfort: A Systematic Review

Background

Digital devices such as smartphones, tablets, computers, and laptops are used for various purposes. The digital display quality has been improved, making it less tiring and more favoured among users. This study aimed to review the visual comfort of digital devices and the preferences of digital display settings that enhance the visual comfort experienced by digital device users.

Methods

A search of PubMed, EBSCO host MEDLINE Complete, Scopus database, Google Scholar, and manual citation review was conducted, covering the period between 2010 and 2022. The criteria were selected based on the PRISMA statements. The search mainly focused on finding the existing literature on digital devices that contribute to visual discomfort and digital device settings that provide better visual comfort.

Results

The database search resulted in 533 references via the application of Microsoft Excel. There were 28 studies included in the final assessment. Twelve studies accounted for digital devices that contributed to visual discomfort, while another sixteen studies for digital device settings provided better visual comfort.

Conclusion

Digital displays with high luminance contrast, positive polarity and adequate colour were preferred for better visual comfort. Meanwhile, smaller fonts were preferred for desktops and laptops, while larger fonts were favoured for smartphones. This study provides insights for digital display developers to learn and improve their display technology to fit the preferences expressed.

Is there magnocellular facilitation of early neural processes underlying visual word recognition? Evidence from masked repetition priming with ERPs

An influential theory in the field of visual object recognition proposes that it is the fast magnocellular (M) system that facilitates neural processing of spatially more fine-grained information rather the slower parvocellular (P) system. While written words can be considered as a special type of visual objects, it is unknown whether magnocellular facilitation also plays a role in reading. We used a masked priming paradigm that has been shown to result in neural facilitation in visual word processing and tested whether these facilitating effects are mediated by the magnocellular system. In two experiments, we manipulated the influence of magnocellular and parvocellular systems on visual processing of a contextually predictable target character by contrasting high versus low spatial frequency and luminance versus color contrast, respectively. In addition, unchanged (normal) primes were included in both experiments as a manipulation check. As expected, unchanged primes elicited typical repetition effects in the N1, N250 and P3 components of the ERP in both experiments. In the experiment manipulating spatial contrast, we obtained repetition effects only for the N1 component for both M- and P-biased primes. In the luminance versus color contrast experiment, repetition effects were found in N1 and N250 for both M- and P- biased primes. Furthermore, no interactions were found between M-vs. P-biased prime types and repetition. Together these results indicate that M- and P- information contributes jointly to early neural processes underlying visual word recognition.

Motion extrapolation in the flash-lag effect depends on perceived, rather than physical speed

In the flash-lag effect (FLE), a flash in spatiotemporal alignment with a moving object is misperceived as lagging behind the moving object. One proposed explanation for this illusion is based on predictive motion extrapolation of trajectories. In this interpretation, the diverging effects of velocity on the perceived position of the moving object suggest that FLE might be based on the neural representation of perceived, rather than physical, velocity. By contrast, alternative explanations based on differential latency or temporal averaging would predict that the FLE does not rely on such a representation of perceived velocity. Here we examined whether the FLE is sensitive to illusory changes in perceived speed that result in changes to perceived velocity, while physical speed is constant. The perceived speed of the moving object was manipulated using revolving wedge stimuli with variable pattern textures (Experiment 1) and luminance contrast (Experiment 2). The motion extrapolation interpretation would predict that the changes in FLE magnitude should correspond to the changes in the perceived speed of the moving object. In the current study, two experiments demonstrated that perceived speed and FLE magnitude increased in the dynamic pattern relative to the static pattern conditions, and that the same effect was found in the low contrast compared to the high contrast conditions. These results showed that manipulations of texture and contrast that are known to alter judgments of perceived speed also modulate perceived position. We interpret this as a consequence of motion extrapolation mechanisms and discuss possible explanations for why we observed no cross-effect correlation.

Effects of luminance contrast, averaged luminance and spatial frequency on vection

Changing the speed, size and material properties of optic flow can significantly alter the experience of vection (i.e. visually induced illusions of self-motion). Until now, there has not been a systematic investigation of the effects of luminance contrast, averaged luminance and stimulus spatial frequency on vection. This study examined the vection induced by horizontally oriented gratings that continuously drifted downwards at either 20° or 60°/s. Each of the visual motion stimuli tested had one of: (a) six different levels of luminance contrast; (b) four different levels of averaged luminance; and (c) four different spatial frequencies. Our experiments showed that vection could be significantly altered by manipulating each of these visual properties. Vection strength increased with the grating's luminance contrast (in Experiment 1), its averaged luminance (in Experiment 2), and its spatial frequency (in Experiment 3). Importantly, interactions between these three factors were also found for the vection induced in Experiment 4. While simulations showed that these vection results could have been caused by effects on stimulus motion energy, differences in perceived grating visibility, brightness or speed may have also contributed to our findings.

A gain-control disparity energy model for perceived depth from disparity

Luminance contrast is one of the key factors in the visibility of objects in the world around us. Previous work has shown that the perceived depth from binocular disparity depends profoundly on the luminance contrast of the image. This dependence cannot be explained by existing disparity models, such as the well-established disparity energy model, because they predict no effect of luminance contrast on depth perception. Here, we develop a model for disparity processing that incorporates contrast normalization of the neural response into the disparity energy model to account for the contrast dependence of perceived depth from disparity. Our model contains an array of disparity channels, each with a different disparity selectivity. The binocular images are first processed by the left- and right-eye receptive fields of each channel. The outputs of the two receptive fields are combined linearly as the excitatory disparity sensitivity and then fed into a nonlinear contrast gain control mechanism. The perceived depth is determined by the weighted average of all the disparity channels that respond to the binocular images. This model provides the first analytic account of how luminance contrast affects perceived depth from disparity.

Color for the perceptual organization of the pictorial plane: Victor Vasarely's legacy to Gestalt psychology

Victor Vasarely's (1906-1997) important legacy to the study of human perception is brought to the forefront and discussed. A large part of his impressive work conveys the appearance of striking three-dimensional shapes and structures in a large-scale pictorial plane. Current perception science explains such effects by invoking brain mechanisms for the processing of monocular (2D) depth cues. Here in this study, we illustrate and explain local effects of 2D color and contrast cues on the perceptual organization in terms of figure-ground assignments, i.e. which local surfaces are likely to be seen as "nearer" or "bigger" in the image plane. Paired configurations are embedded in a larger, structurally ambivalent pictorial context inspired by some of Vasarely's creations. The figure-ground effects these configurations produce reveal a significant correlation between perceptual solutions for "nearer" and "bigger" when other geometric depth cues are missing. In consistency with previous findings on similar, albeit simpler visual displays, a specific color may compete with luminance contrast to resolve the planar ambiguity of a complex pattern context at a critical point in the hierarchical resolution of figure-ground uncertainty. The potential role of color temperature in this process is brought forward here. Vasarely intuitively understood and successfully exploited the subtle context effects accounted for in this paper, well before empirical investigation had set out to study and explain them in terms of information processing by the visual brain.

Effects of luminance contrast and character size on reading speed

Both luminance contrast and character size are critical factors affecting reading performance. Previous studies reported on the effect of luminance contrast on the reading-speed function, that is, the relationship between reading speed and character size. In particular, when contrast was reduced, the critical print size (CPS) was found to shift to a larger character size even though the maximum reading speed and function shape did not change [Japanese Journal of Ophthalmology 52(1) (2008) 44-47]. In the present study, the effect of luminance contrast on the reading function was quantitatively examined. Japanese phrases with a luminance contrast of 0.03-0.99 were prepared as stimuli. Observers with normal vision were asked to read aloud phrases with several character sizes. Then, the reading functions were obtained for each luminance contrast. CPS was found to increase as the luminance contrast decreased. The relationship between contrast and CPS was linear in log-log coordinates, that is, log-CPS increased as the log-contrast of the characters decreased. It was found that the contrast of the stimulus systematically affects the location of the reading function.

Discrimination of colors by red-green color vision-deficient observers through digitally generated red filter

Previous studies have shown that with the use of tinted lenses (or colored filters), individuals with red-green color vision deficiency (CVD) report an improvement in their performance on certain color vision tests. In this context, this study examines the effects of a digitally generated red-colored filter and identifies the mechanism mainly responsible for the changes in red-green CVD observers' performance on a D-15 arrangement test performed using the filter. We simulate the red filter digitally with the spectral transmittance similar to that of the X-Chrom, which is a red-tinted lens. Fourteen red-green CVD subjects are subjected to the D-15 test on a computer monitor under four filter conditions, consisting of one condition without the filter and three conditions with the filter, corresponding to the opacity of the red filter. The results show that while the simulated red filter improves the performance of deutans to arrange the caps in the D-15 test, this is not the case for protans. In addition, considerations based on the human cone-contrast model enable us to identify that the improvement in deutan observers largely results from the increase in the luminance contrast between stimuli and a background. To summarize, the red filter simulated in this study induces different changes in the red-green CVD observer luminance contrast between the protan and deutan types, with the result that the performance of deuteranopes improves while that of protanopes deteriorates.

The effects of luminance contrast, colour combinations, font, and search time on brand icon legibility

This study explored and identified the effects of luminance contrast, colour combinations, font, and search time on brand icon legibility. A total of 108 participants took part in the experiment. As designed, legibility was measured as a function of the following independent variables: four levels of luminance contrast, sixteen target/background colour combinations, two fonts, and three search times. The results showed that a luminance contrast of 18:1 provided readers with the best legibility. Yellow on black, yellow on blue, and white on blue were the three most legible colour combinations. One of this study's unique findings was that colour combinations may play an even more important role than luminance contrast in the overall legibility of brand icon design. The 12-s search time corresponded with the highest legibility. Arial font was more legible than Times New Roman. These results provide some guidance for brand icon and product advertisement design.

A second-order orientation-contrast stimulus for population-receptive-field-based retinotopic mapping

Visual field or retinotopic mapping is one of the most frequently used paradigms in fMRI. It uses activity evoked by position-varying high luminance contrast visual patterns presented throughout the visual field for determining the spatial organization of cortical visual areas. While the advantage of using high luminance contrast is that it tends to drive a wide range of neural populations - thus resulting in high signal-to-noise BOLD responses - this may also be a limitation, especially for approaches that attempt to squeeze more information out of the BOLD response, such as population receptive field (pRF) mapping. In that case, more selective stimulation of a subset of neurons - despite reduced signals - could result in better characterization of pRF properties. Here, we used a second-order stimulus based on local differences in orientation texture - to which we refer as orientation contrast - to perform retinotopic mapping. Participants in our experiment viewed arrays of Gabor patches composed of a foreground (a bar) and a background. These could only be distinguished on the basis of a difference in patch orientation. In our analyses, we compare the pRF properties obtained using this new orientation contrast-based retinotopy (OCR) to those obtained using classic luminance contrast-based retinotopy (LCR). Specifically, in higher order cortical visual areas such as LO, our novel approach resulted in non-trivial reductions in estimated population receptive field size of around 30%. A set of control experiments confirms that the most plausible cause for this reduction is that OCR mainly drives neurons sensitive to orientation contrast. We discuss how OCR - by limiting receptive field scatter and reducing BOLD displacement - may result in more accurate pRF localization as well. Estimation of neuronal properties is crucial for interpreting cortical function. Therefore, we conclude that using our approach, it is possible to selectively target particular neuronal populations, opening the way to use pRF modeling to dissect the response properties of more clearly-defined neuronal populations in different visual areas.

An evaluation of different measures of color saturation

We investigated how well seven saturation measures defined in CIECAM02, HSV, DKL, LAB, LUV, and CIE 1931 xyY color spaces correspond to human perception of saturation. We used a paradigm that allowed us to measure the perceived saturation of several standard color stimuli in many different directions of color space. We implemented this paradigm at different levels of luminance and varied background luminance relative to the luminance of our color stimuli in order to ensure the generality of our approach. We found that varying background luminance changed the relative saturation of the standard colors. Raising the overall luminance level did not have such an effect. We compared the results of our measurements to the predictions of the seven saturation measures. All of the measures could predict our observers' judgments of saturation reasonably well. The measures that are based on measurements of discrimination thresholds (LUV, LAB, CIECAM02) performed best on average. However, some of the perceptual effects induced by changing background luminance could not be predicted by any measure.