Color Perception: Mental processing of chromatic signals (COLOR VISION) from the eye by the VISUAL CORTEX where they are converted into symbolic representations. Color perception involves numerous neurons, and is influenced not only by the distribution of wavelengths from the viewed object, but also by its background color and brightness contrast at its boundary.Color Perception Tests: Type of vision test used to determine COLOR VISION DEFECTS.Color: The visually perceived property of objects created by absorption or reflection of specific wavelengths of light.Color Vision: Function of the human eye that is used in bright illumination or in daylight (at photopic intensities). Photopic vision is performed by the three types of RETINAL CONE PHOTORECEPTORS with varied peak absorption wavelengths in the color spectrum (from violet to red, 400 - 700 nm).Lighting: The illumination of an environment and the arrangement of lights to achieve an effect or optimal visibility. Its application is in domestic or in public settings and in medical and non-medical environments.Color Vision Defects: Defects of color vision are mainly hereditary traits but can be secondary to acquired or developmental abnormalities in the CONES (RETINA). Severity of hereditary defects of color vision depends on the degree of mutation of the ROD OPSINS genes (on X CHROMOSOME and CHROMOSOME 3) that code the photopigments for red, green and blue.Rod-Cone Interaction: Reciprocal action of two vertebrate photoreceptor cells (RODS AND CONES). Rod-cone interaction occurs during MESOPIC VISION in which both rods and cones are active in light transduction to the VISUAL CORTEX. Such interaction can influence visual sensitivity and luminous efficiency.Perception: The process by which the nature and meaning of sensory stimuli are recognized and interpreted.Contrast Sensitivity: The ability to detect sharp boundaries (stimuli) and to detect slight changes in luminance at regions without distinct contours. Psychophysical measurements of this visual function are used to evaluate visual acuity and to detect eye disease.Photic Stimulation: Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.Psychophysics: The science dealing with the correlation of the physical characteristics of a stimulus, e.g., frequency or intensity, with the response to the stimulus, in order to assess the psychologic factors involved in the relationship.Retinal Cone Photoreceptor Cells: Photosensitive afferent neurons located primarily within the FOVEA CENTRALIS of the MACULA LUTEA. There are three major types of cone cells (red, blue, and green) whose photopigments have different spectral sensitivity curves. Retinal cone cells operate in daylight vision (at photopic intensities) providing color recognition and central visual acuity.Form Perception: The sensory discrimination of a pattern shape or outline.Sensory Thresholds: The minimum amount of stimulus energy necessary to elicit a sensory response.Discrimination (Psychology): Differential response to different stimuli.Light: That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.Visual Cortex: Area of the OCCIPITAL LOBE concerned with the processing of visual information relayed via VISUAL PATHWAYS.Visual Fields: The total area or space visible in a person's peripheral vision with the eye looking straightforward.Ultrasonography, Doppler, Color: Ultrasonography applying the Doppler effect, with the superposition of flow information as colors on a gray scale in a real-time image. This type of ultrasonography is well-suited to identifying the location of high-velocity flow (such as in a stenosis) or of mapping the extent of flow in a certain region.Visual Perception: The selecting and organizing of visual stimuli based on the individual's past experience.Hair Color: Color of hair or fur.Motion Perception: The real or apparent movement of objects through the visual field.Social Perception: The perceiving of attributes, characteristics, and behaviors of one's associates or social groups.Speech Perception: The process whereby an utterance is decoded into a representation in terms of linguistic units (sequences of phonetic segments which combine to form lexical and grammatical morphemes).Depth Perception: Perception of three-dimensionality.Eye Color: Color of the iris.Pigmentation: Coloration or discoloration of a part by a pigment.Auditory Perception: The process whereby auditory stimuli are selected, organized, and interpreted by the organism.Pain Perception: The process by which PAIN is recognized and interpreted by the brain.Time Perception: The ability to estimate periods of time lapsed or duration of time.Space Perception: The awareness of the spatial properties of objects; includes physical space.Pitch Perception: A dimension of auditory sensation varying with cycles per second of the sound stimulus.Size Perception: The sensory interpretation of the dimensions of objects.Taste Perception: The process by which the nature and meaning of gustatory stimuli are recognized and interpreted by the brain. The four basic classes of taste perception are salty, sweet, bitter, and sour.Touch Perception: The process by which the nature and meaning of tactile stimuli are recognized and interpreted by the brain, such as realizing the characteristics or name of an object being touched.Nature: The system of all phenomena in space and time; the totality of physical reality. It is both a scientific and philosophic concept appearing in all historic eras. (Webster 2d; Dr. James H. Cassedy, NLM History of Medicine Division)Internet: A loose confederation of computer communication networks around the world. The networks that make up the Internet are connected through several backbone networks. The Internet grew out of the US Government ARPAnet project and was designed to facilitate information exchange.Portal Vein: A short thick vein formed by union of the superior mesenteric vein and the splenic vein.Hair: A filament-like structure consisting of a shaft which projects to the surface of the SKIN from a root which is softer than the shaft and lodges in the cavity of a HAIR FOLLICLE. It is found on most surfaces of the body.Software: Sequential operating programs and data which instruct the functioning of a digital computer.Tablets: Solid dosage forms, of varying weight, size, and shape, which may be molded or compressed, and which contain a medicinal substance in pure or diluted form. (Dorland, 28th ed)User-Computer Interface: The portion of an interactive computer program that issues messages to and receives commands from a user.Blogging: Using an INTERNET based personal journal which may consist of reflections, comments, and often hyperlinks.Colorimetry: Any technique by which an unknown color is evaluated in terms of standard colors. The technique may be visual, photoelectric, or indirect by means of spectrophotometry. It is used in chemistry and physics. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Algorithms: A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.Image Processing, Computer-Assisted: A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.Computer Graphics: The process of pictorial communication, between human and computers, in which the computer input and output have the form of charts, drawings, or other appropriate pictorial representation.Physics: The study of those aspects of energy and matter in terms of elementary principles and laws. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Gilbert Disease: A benign familial disorder, transmitted as an autosomal dominant trait. It is characterized by low-grade chronic hyperbilirubinemia with considerable daily fluctuations of the bilirubin level.BooksPrintingInkPupil Disorders: Conditions which affect the structure or function of the pupil of the eye, including disorders of innervation to the pupillary constrictor or dilator muscles, and disorders of pupillary reflexes.