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Essay / Contrast, Color and Size and Their Effects on Visual Perception and Signal Strength world around us through the light that enters our eyes. Throughout evolution, processing signals and distinguishing them from surrounding noise has allowed humans to take necessary actions in response to environmental changes. These signals processed by the retina and visual cortex are essential aspects of cognition, because knowing how to differentiate target signals from background noise is what allows humans to survive. This review examines theories and concepts focused on visual perception and analyzes the most important aspects for signal processing: contrast, color and size. When applied strictly to user experience, these concepts have significant implications, as this understanding helps distinguish an interface that is usable and effective from one that is not. By examining a real-world design example, Boston's iconic Citgo sign, we can begin to recognize how a critical understanding of visual perception, the biology of the human eye, and bottom-up design has broad implications for user experience. plagiarism. Get a tailor-made essay on “Why violent video games should not be banned”?Get the original essayDiscussionVisual perception and bottom-up processingVisual perception is the way humans process signals through visible light and its interaction with stimuli environmental. Sensing signals from our environment allows humans to take necessary precautions and actions in response to environmental changes. Although the nervous system is very adept at recognizing and interpreting signals, they are not always clear. Signals are most often ambiguous, so determining signal strength will allow better discrimination between a signal and its noise. The stronger the signal, the easier it is to process compared to its background noise. Bottom-up processing. The human eye, due to its many connections with the optic nerve, is very sensitive to signals. Light enters the eye through the cornea, then the lens focuses it on the photoreceptors (i.e. cones and rods) located in the retina. The cones are "densely packed within the fovea" to help produce high resolution and color vision, and the rods are located at the periphery of the retina to help process light and movement in various environmental conditions. Through a series of rapid eye movements, humans can process multiple signals at once. In a single glance, the eye detects contrast, color, contour, movement, and size, all of which will be covered in the following sections. Contrast, edge and color contrast are one of the most important factors in determining the strength of a signal. Contrast is the degree to which a stimulus is different from other stimuli around it. It detects the change between foreground and background. Just like how our brain processes signals, the higher the contrast, the more the stimulus is perceived by the brain. When it comes to design, it is essential to find a balance between maximum (strongest) contrast and threshold (lowest) contrast in order to produce the optimal signal. Over-design or design to the limit of barely perceptible differences (JND)is a delicate balance and must be weighed heavily, as visual perception varies greatly depending on the viewer and viewing conditions. Luminance and contour. Luminance is considered to have the greatest influence on contrast. Luminance is defined as the reflection or emission of visible light from a surface, and is also described as the measure of perceived brightness (although luminance and brightness are not the same in practice). Due to the greater number of light-processing rods in the retina, humans are therefore more sensitive to luminance. This sensitivity to luminance allows humans to easily detect changes and adapt to various lighting conditions. Throughout evolution, humans have evolved to identify changes in the environment through enhancements of contours (edges) or variations in luminance levels. Edges are created when the luminance of an object changes rapidly, creating high contrast between the stimulus and its background. Once an edge is detected, the nerves in the eye exaggerate and amplify it, allowing the visual cortex to process the object in our field of vision. This edge detection allows humans to recognize objects in our environment and assign value and meaning to them based on their appearance, hue, and saturation. Tints allow humans to distinguish one spectral color from another on the visible light spectrum. Saturation, or purity of a hue, is the intensity of a hue at its dominant wavelength. When a hue is in its purest form, it is the most saturated and therefore has a great influence on contrast and signal intensity. Conversely, an unsaturated hue would have “contributions from many other wavelengths” and much lower contrast. It's common to avoid using highly saturated hues in designs, or at least use them sparingly, as pure hues can tire the eye due to strong contrast. In general, humans find pleasure and appeal in higher saturated hues, but it's important to keep in mind the downsides of using a hue with maximum saturation. Motion and SizeMotion. Motion detection is one of the most important functions of visual perception, as it has a significant impact on contrast, depth and luminance sensitivity. The human eye is very sensitive to movement, as it is processed and calculated by nerve endings located at the periphery of the retina. Movement "reflects a change in a person's visual environment" and has a direct impact on understanding how real-world stimuli form and facilitate behavioral responses and actions. Because movement is design-related, overuse can cause overstimulation because humans can't block it. Designers must use change and movement deliberately and strategically in order to create meaning. The size of a stimulus, along with luminance and contour, are equally important for signal processing. The size of a stimulus has a direct relationship with the signal. As the size of a stimulus increases, the strength of the signal also increases. Size can be greatly affected by other influencing factors and complex factors, such as viewing distance, viewing angle and environmental conditions. When comparing viewing distance and size, there is an inverse relationship; as the distance increases, the perceived size appears smaller. In contrast, viewing angle and size have a direct relationship: as the angleview increases, the size of the stimulus also increases. Design Case Although each signal processing concept has been described separately in the sections above, in reality they all influence one. each other. By examining a real-world design case, looking at the Boston Citgo sign while driving at night, an analysis will be conducted to determine whether its design adheres to or goes against bottom-up visual perception. Luminance and edges. The sharp horizontal and vertical edges that form the panel boundaries are one of the first signals the driver will process. These abrupt changes in luminance along the edges add a stark contrast against its dark background, only making the panel more visible and the signal more intense. Likewise, the red triangle also presents a strong contrast against its white background due to its shape and sharp edges. Since humans are neurologically tuned to detect contoured edges, the nerves in the eye amplify the edges both on the sides of the panel and around the triangle, and enhance the perceived contrast. At night, the luminance emitted by the LED lights inside the sign is incredibly intense, sending an equally strong signal to the visual cortex. Because the Citgo sign is located in the driver's line of sight while traveling west on Storrow Drive, perceived high light levels may be hazardous to the driver's safety. Particularly in poor weather conditions, the glare of bright lights can increase the risk of an accident, because the perceived brightness can temporarily blind the driver or cause an "afterimage", which results in momentarily blurred and spotted vision . Given that humans are generally more sensitive to changes in luminance, it is not surprising that looking at the Citgo sign while driving could interfere with drivers' safety. Saturation and hue. The Citgo panel LEDs not only contain strong luminance contrast, but also possess high saturation. The red and blue hues used in the Citgo logo have the highest intensity, as they are both at their dominant wavelengths in the visible light spectrum. It's common to use saturation sparingly in interface design because pure hues can strain the eye due to high contrast. Red generally has good visibility due to the high number of red-sensitive cones in the fovea, but has poor visibility in low light conditions. The retina is less sensitive to blue than to red, but despite having fewer blue-sensitive cones, the human eye tends to shift toward the blue end of the color spectrum at low levels. lighting, which makes it appear as if it has a higher luminance value. . Although red and blue hues are at either end of the visible light spectrum, placing them close to each other, especially at full saturation, is a poor design decision. Red hues generally push toward the foreground of a stimulus and blue fades into the background. Because of this proximity, in addition to the strong luminance of the white background, the red and blue lights create a quivering effect, resembling movement at the periphery of the eye. While the Citgo sign already uses movement through different blinking and high contrast patterns, the excessive movement created by saturated hues will only cause more distraction. Boston's Citgo sign is visible from many areas of the city, as the large sixty-foot sign sits above the buildings surrounding it. Due to the size and location of the panel,drivers heading west on Storrow Drive get a particularly good view of it. To a motorist at night, the sign stands out even more among the surrounding buildings, displaying a strong contrast with the night sky and nearby buildings. Regardless of the viewing angle or distance, the contrast of the panel is so strong that even from a distance the panel sends a powerful signal to the driver. Especially while driving, this high contrast can be incredibly dangerous, as the appearance of these strong signals can quickly fatigue the sensory system due to rapid eye movements. LEDs, with their higher luminance and saturation levels, generally have much abrupt onset times than other light sources. Design Recommendations The Citgo sign's use of strong contrast, while still meeting the visibility goal, may present dangerous driving conditions for drivers, especially at night. Creating such powerful signals through the combination of intense luminance, large size, moving patterns, and highly saturated hues will eventually fatigue the sensory system. For interface designers, the overarching goal of interaction design as it relates to visual perception is to find the optimal contrast. One suggestion is to use split complement theory to reduce the saturation of the red and blue hues of the Citgo logo. Alternatively, mixing darker shades with existing red and blue can also help reduce intensity. Additionally, reducing luminance, especially at night, will reduce the strength of the signal sent to passers-by. This reduction can reduce perceived brightness and minimize glare caused by bright lights. Both suggested contrast changes will achieve a more controlled and predictable result. Keep in mind: this is just a sample. Get a personalized article from our expert writers now. Get a Custom Essay Conclusion Visual perception is how humans understand and process our environment through the light that enters our eyes. Through understanding signals and noise, the biology of the eye, and how visual contrast relates to the psychology and behavior of signal processing, designers will be able to apply these principles to 'exercising greater control over user response to design. Designers strive to produce predictable results, and to achieve this they apply psychological and perceptual concepts related to signal strength and contrast. While each of these factors plays its respective role in determining signal strength and contrast, the question is how the combination of these concepts affects visual perception and design. Looking at Boston's iconic Citgo sign, we can see how this combination of influencers can have a very strong negative effect on the human eye. Understanding how each factor comes into play will only make a designer more effective. By understanding how each factor comes into play, designers should work to reduce the burden we place on users by making designs even more effective and visually appealing. ReferencesAbdi, H. (1966). Signal_detection_theory[1].pdf (pp. 1 to 9). pp. 1–9. Albers, J. (1975). Interaction of Color (revised edition). Retrieved from http://www.amazon.co.uk/dp/0300018460Anderson, B.L. (2003). The role of occlusion in the perception of depth, lightness and opacity. Psychological Review, Vol. 110, pp. 785-801. https://doi.org/10.1037/0033-295X.110.4.785 Aydin, T., Čadík, M., Myszkowski, K. and Seidel, HP, 1(212), 69-76./10.1145/2072298.2071997
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