Copyright ©2001-2017 Marshall Rendina. All rights reserved.
1. Vision is Electrochemical
Color receptors may be effected depending on the angle of a photon hitting them, and wavelength, with shorter waves causing more stimulation in a shorter time. The molecular structures of different cones are affected as they absorb different wavelengths of light. Cones are sensitive to a range of frequencies of green, blue, and red light. Light as it is received by the eyes in different wavelengths and added together differs from light reflected by objects that absorb or subtract light, and this is counterintuitive to primary colors that are mixed to form others through the absorption of light. Rods are sensitive to a single photon and responsible for night vision. Cones require more photons or stimulation to signal the photochemical process by which a cell is polarized electrically and a neural signal is inhibited or sent to the brain through the optic nerve, in most cases the signal must be inhibited to produce the effect of color and the receptor cells continually send signals. A given cone may produce the same response from different frequencies of light at different intensities – each frequency produces a given amount of energy and a single cone may be fooled by an equal amount of energy being absorbed in a different color. Color is determined by many responses within an area of the cones with three sensitivities. There are fewer blue photoreceptor cells in the fovea, and area of densely distributed cones. The fovea is located in the macula, which is part of the retina. The retina contains around 120 million rod cells and 6 million cone cells.
2. Vision is Spatial
The eyeball is relatively spherical, with a hemispherical retina, and a circular pupil. Visual perception is relatively circular with one eye open, with the field of vision being blocked by the nose, face, and forehead. The field may be slightly wider horizontally. The lens will focus light from across the pupil that has been refracted through the cornea into the retina in either eye.
Cones do not extend to the periphery of vision, and color is most accurately perceived in the central two thirds of the field. The rods and cones closer to the edges of the field of vision are less sensitive and require more stimuli to activate. Most of the photoreceptor cells are in the center of the retina, sensitive to what the eye is viewing directly. The eye has a blind spot slightly off center center where the optic nerve is, and is ignored by the brain.
With both eyes open the field of vision is widened both horizontally and vertically in the center. The combined overall field is 130-135 degrees vertically and up to 200 degrees horizontally. The combined field results from the shapes of the other fields being superimposed over a circular area with shared information in the middle. When viewing directly ahead, the two fields of vision are more or less the combination of two circular fields. Around 120 degrees of the field is covered by both eyes, with the two eyes covering around 40 degrees of unique outer area. The different positions of the eyes gives us depth perception. The angles of sight differ because of the distance between the eyes, and gives us additional perspective cues and the ability to see around objects. Either eye may dominate, providing preferred visual information, and both hemispheres control both eyes.
When the fields of view are combined, they become a single image, each eye filling in what the other eye cannot see in the direction of the opposite eye, and away from the opposite eye because of its position. Opposite eyes will be able to perceive the area in the top center where the eye socket and nose block vision for a single eye, and in the bottom center where the face has blocked the field of vision. Information from both eyes is recombined into a single image after it has been picked up by the photoreceptors. It is unclear whether duplicate information is disregarded or combined. Many experiments exist to test the process by which duplicate information is recognized.
Vision is more precise than sound as the photons have relatively uniform amplitudes and the intensity of light is caused by their quantity. Receptors in vision are distributed two dimensionally, whereas in sound they are relatively one dimensional, though additional dimensionality may be perceived by the spiral nature of the cochlear, overlapping of adjacent nerves, and time-based cues. A single eye can perceive depth, though less accurately, and especially if the eye moves or the observer moves.
3. Color and Intensity Allow us to Distinguish Unique Objects
Adjacent objects of similar colors are more difficult to distinguish. The angle of light, its intensity, and dilation of the pupil also affects the ability to distinguish colors. Colors may be perceived as either black or white if there is intense enough light or if there is too little, and when both a very light color and very dark color are present, one may disappear.
When two images of equal light intensity are overlaid with each other, the mind will have to choose which image will be in the foreground and which image will be in the background.
Objects of the same color set against backgrounds of different colors or intensities will appear light or darker.
White objects or areas appear larger than black objects of the same size. The light spreads or effects receptors less selectively than with less stimulation from a darker object.
Color channels may be divided for each eye, which is the basis of stereoscopic images.
The same color will be received by both eyes from a source and it is the spacing of the eyes that allows for distance-perception. It is unclear whether color is associated with spatial information. Because sound is spatial and vision is spatial they are associated in this sense.
4. Vision is Time-Based
Motion blur often results from fast moving objects.
When images are presented in succession rapidly enough they will appear to move, which is the basis of film and video.
Rapid flashes of light may induce seizures in certain individuals.
CNS depressants may cause flickering at normal frame rates when watching television or movies as each frame can be perceived independently.
Psychedelics can cause motion blurs to be present for longer intervals of time.
A rotating fan or helicopter blades may be perceived as rotating in either direction depending on their speed and the location of the viewer.
5. Many Effects are Possible Using Repetitions and Geometric Forms
Retinal fatigue will result as grey dots in spaces between geometric grids where the eye has not been focused. This results in negative afterimages for other shapes when viewed for a prolonged period, and opposite colors will appear on a white background.
Certain types of objects may appear to rotate depending on position and moment of the head.
Vertically symmetrical objects may appear top heavy.
Directional perspective is affected by surrounding stimuli – straight lines may bend with those it passes through or past, the same pair of eyes may look in opposite directions depending on the position of the head. This may also cause figure-ground relationships to shift, or those of concavity and convexity.
Moiré patterns may result from superimposed repeating geometric forms in which a third geometric form appears.
Repeating similar objects such as circles are grouped into shapes. Variations of repetitions can cause other shapes to appear, or shapes may appear at the endpoints of repeating lines.
Missing information can be replaced or identified with only outlines or partial information present.
Vertical lines generally appear to be longer than horizontals of the same length.
Objects may appear to be longer or shorter depending on horizontal and vertical relationships of divided spaces, geometric shapes between equally distanced points, differing surrounding geometric stimuli with shapes or lines of same sizes, positions of similar shapes or lines at different angles, interior and exterior shapes and lines, positions relative to other objects, and objects of the same size at different points in cues establishing perspective.
6. Many Illusions Can be Caused by Depth Perception
The use of irrational geometry in two dimensions that is processed differently three dimensionally, with relative sizes and placement of objects in an image.
Reversible figures such as cubes and cylinders.
Figure and ground may alternate with similar negative spaces or symmetrical geometric objects with conflicting perception of sides.
Endless spaces may be created through repeating geometric forms within one another.
7. Vision is Focus-Oriented
Objects in the center of the field of vision will have the most precise and accurate perceptions of color and distance as they are directly in alignment with the fovea, the area with the most photoreceptor cells. The eye can focus on objects directly ahead depending on their distance with the lens. The cornea covers the iris, pupil, and lens, and refracts light through the pupil, though it does not focus. The iris is responsible for the aperture of the pupil. The point of focus will be the center of attention, and this is in contrast to attention in hearing, in which the stimuli that is the center of attention is selected after it is processed. In vision, the stimuli may be selected before it comes into contact with the retina or sent to the optic nerve. One can still process information that is not in the center of the eye, although its effect will be lesser. More movement or intensity of light is then required in the edges of the field of vision to produce the same perceptual effect as being in the center of the field of vision.
Overlapping text or objects in a video that change in size while moving on x and y axes will appear to travel both forward and backward simultaneously when getting smaller.
8. Vision Induces Cognitive Responses
The responses from visual information are perhaps cognitive at first, and after being processed may cause emotions to arise based on the imagery and associations with them. It is unclear whether light and color alone in juxtapositions and abstract forms illicit emotional responses from viewers in the way that music does prior to being associated with memories or processed as cues, producing the effect of being frightening, beautiful, depressing, happy, and so forth.
The artist who created the images may have definitely expressed some form of emotion in producing the image, though the emotion is felt after the cognitive impression of the image by the viewer. In music, emotion may be felt before cognitive judgments are made about the piece or song, though in many instances pieces may lack emotional qualities that one may immediately identify and it will be processed as an attempt to organize sound cognitively. Likewise, in art emotion may be minimal or not be felt at all, and only an attempt to organize geometrically the objects presented is made. It would be unusual for a piece of visual art to bypass any conscious judgments and directly effect one’s emotions, as even the most indistinguishable expressions of feeling arouse attempts to identify objects in the paintings.
Text and letters activate the part of the mind that uses language. It is understood that words are read as whole visual symbols based on the content of letters and their first and last letters alone. This makes sense as words in Chinese and other languages are each a single image themselves. This is in contrast to sound, in which words are identified by the progression of phonemes in a definite order from start to finish. Visual identification of words only requires content and boundaries of start and finish.
Subconscious cues may be encountered without one’s knowing, without them recognizing the image, and an association with an image from memory is made depending on one’s surroundings. Related material will then be conjured up in consciousness or in conversation though in a different context, and the object or idea will appear in reality – thus giving the impression of precognition.
9. Vision is Stored and Recalled in Memory
Images may cause memories to be recalled similarly to how sound and music cause memories to arise, though this likely takes place within or closer to consciousness itself, requiring a cognitive identification and association with the image, unless the visual stimuli is hypnotic in nature or induces an altered state, or is abstract and the mind produces an association with a symbol.
How vividly and how long images are stored in memory is likely related to the importance or emotional effect they have on an individual – the paths used to access the images are more deeply rooted in the mind’s more essential functions related to survival, fear, desire, and so forth.
10. Vision is Related to Movement by Spatial Perception
Vision does not illicit movement responses in the way that music does, unless there is first a cognitive reason that is rationally processed, such as moving out of the way of a passing object. Thus vision is not a kinesthetic sense in the way that sound requires nerves to be activated through the movement of matter, but that the nerves are activated by a more fine state of energy similar to that already present within the body – being distinguished from matter coming into contact with the body.
One may close their eyes and visualize where parts of their body are and see within the mind the positions of their hands, feet, and so forth, though less accurately than with the eyes open, and perhaps more so when they move them.
As with the localization of sound and perception of pitch within a spatial area, visualizations of locations of objects likely use the same parts of the brain when they are integrated. This spatial sense is independent of external stimuli – locations may be visualized. Thus, a network of pitches arranged into geometric spaces will produce some sense of space and localization, though as stimuli, have none and are all panned in the center. Because sight and sound both require this spatial sense, there must be a degree of overlap, however, notions of exactness are inconsistent, especially those of color-pitch correspondences and shapes associated with certain timbres or phrases in music.
The spatial sense in the mind is not as precise as the part of the mind that involves exact calculations and logic. This part of the mind is much more related to cognition and accessible through consciousness only. The spatial parts of the mind are accessible by a wide array of mental functions, especially those related to vision, sound, movement, and are more interrelated to other states of consciousness, perhaps providing an empty “stage” or space in which sensory information can be processed, imagined, projected, and so forth, both in dreaming, consciousness, imagining, and in meditation.
Images and color may be visualized at the point between both eyes in meditation.
Visual Perception Exercise
Cut a circle and a square or rectangle into opposite sides of a cardboard strip. Focus on what is in the circle far away, and then the whole scene outside the circle. Move the paper closer or further away. Pay attention to the focus of the eyes inside and outside the circle. Try this with the square or rectangle. Try this using your thumb and index finger to make a circle. Focus on your hand, then what is inside the circle. Try this with a display and outdoors.