Term
| Inverse projection problem |
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Definition
| An image projected on the retina (2-D) could have been caused by an infinite number of different (3-D) objects; thus, a retinal image cannot unambiguously specify a stimulus |
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Term
| Other reasons object perception is difficult for computers |
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Definition
| 1) objects need to be separated; 2) objects can be hidden or blurred; 3) changes in brightness caused by different things |
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Term
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Definition
| Objects look different (have same properties) from different angles; geons are view invariant, according to recognition-by-components theory |
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Term
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Definition
| Process of combining individual features (small parts) to yield percepts of larger, whole objects |
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Term
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Definition
| Series of laws of perceptual organization explaining how we perceptually combine parts of objects into whole objects |
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Term
| Law of simplicity (AKA law of good figure, AKA Pragnanz) |
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Definition
| Gestalt law stating that every stimulus pattern is seen in such a way that the resulting structure is as simple as possible (ex: Olympic rings) |
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Term
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Definition
| Gestalt law stating that similar things appear to be grouped together (ex: grouping people wearing similar clothes) |
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Term
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Definition
| Gestalt law stating that points resulting in straight or smoothly curved lines are seen as belonging together; lines tend to be seen in such a way as to follow the smoothest path or interpretation (ex: flow of pipes) |
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Term
| Law of proximity (AKA law of nearness) |
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Definition
| Gestalt law stating that things that are near to each other appear to be grouped together; can override law of similarity (ex: people standing in lines) |
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Term
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Definition
| Gestalt law stating that things that are moving in the same direction appear to be grouped together (ex: flock of birds flying together) |
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Term
| Law of familiarity (AKA law of meaningfulness) |
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Definition
| Gestalt law stating that things are more likely to form groups when the groups appear familiar or meaningful |
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Term
| Principle of common regions |
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Definition
| Gestalt principle stating that elements that are within the same region of space appear to be grouped together |
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Term
| Principle of connectedness |
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Definition
| Gestalt principle stating that connected regions of a visual stimulus are perceived as a single unit |
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Term
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Definition
| Gestalt principle stating that visual events that occur at the same time will be perceived as belonging together (similar to law of common fate) |
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Term
| Perceptual (figure-ground) segregation |
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Definition
| Process of separating the visual scene into objects and background |
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Term
| Figure-ground distinction (4) |
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Definition
| 1) figure is "thing"-lie; 2) figure is in front of ground; 3) ground is some uniformed material, behind figure; 4) contour separating the two belongs to the figure |
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Term
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Definition
| A figure-ground pattern that perceptually reverses as it is viewed (i.e., figure becomes ground and vice versa) Ex: face-vase pattern |
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Term
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Definition
| Enhanced sensitivity to vertically and horizontally visual stimuli (more H & V indoors, less in nature) |
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Term
| Modern approaches to object perception (2) |
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Definition
| 1) obtain measurements; 2) determine underlying mechanisms responsible for object perception |
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Term
| Evolutionary explanation of perception |
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Definition
| Perceptual systems have evolved to match characteristics of the environment (Ex: detecting bright colors for ripeness) |
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Term
| Recognition by components theory |
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Definition
| Ability to recognize objects based on 3D volumes (geons) that can be combined to create the overall shape of an object |
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Term
| Light from above heuristic |
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Definition
| The assumption that light is usually coming from above, which influences our perception of form in some situations |
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Term
| Functions of color vision (5) |
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Definition
| 1) perceptual organization & segregation; 2) object ID and localization; 3) determining ripeness; 4) visual coding & signage; 5) aesthetics |
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Term
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Definition
| Electromagnetic spectrum b/t 400nm (blue-violet) and 700 (red) |
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Term
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Definition
| Hue (color naming), saturation (vividness or purity), and brightness (amplitude); 200 discriminable hues, 1 million "colors" |
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Term
| Reflected & Absorbed wavelengths |
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Definition
| Reflected wavelengths enter our eyes, absorbed wavelengths don't (Ex: pink object reflects pink light, reflects all others; black = all wavelengths absorbed), white = all wavelengths reflected |
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Term
| Reflection (color of object) |
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Definition
| Amount of each wavelength that is reflected off an object in white light; determined by pigment of object material |
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Term
| Achromatic and chromatic colors |
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Definition
| Achromatic = equal amounts of all wavelengths reflected (white, black, gray); chromatic = some wavelengths reflected more than others (red, green, etc.) |
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Term
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Definition
| Color of light on object (sunlight relatively stable across wavelengths; indoor lighting varies according to wavelength) |
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Term
| Neural mechanisms of color perception |
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Definition
| Three different types of cones (red, green, and blue); blue cones less prevalent |
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Term
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Definition
| Color vision is based on the activity of three different receptor mechanisms, each sensitive to different ranges of light wavelength (L = red, M = green, S = blue); pattern of responses to the three receptors is coded as color |
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Term
| Color matching experiments |
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Definition
| Adjust proportions of blue, green, and/or red wavelengths to perceptually match the color of the test stimulus; normals need 3 or more to match |
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Term
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Definition
| Lights that are physically different (i.e., wavelength distributions) but perceptually identical |
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Term
| Cone spectral sensitivity functions |
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Definition
| Peaks: S (419 nm), M (531 nm); L (558 nm) |
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Term
| # of required cone types (trichromatic theory) |
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Definition
| Two receptor types need to see colors; three needed to see colors accurately |
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Term
| Neural response (absorption) determined by... |
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Definition
| wavelength and intensity; changing intensity of a particular stimulus can result in equal responses (Ex: 550 nm @ 1000 photons identical to 590 nm @ 2000 photons) |
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Term
| Phenomena not accounted for by trichromacy (3) |
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Definition
| 1) color afterimages; 2) simultaneous color contrast; and 3) color scaling (judging percentages of RGBY) |
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Term
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Definition
| Color vision is based on three mechanisms that respond in opposing ways: R/G, B/Y, L/D |
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Term
| How does opponent-process theory explain color afterimages? |
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Definition
| Red light fatigues R+G- mechanisms, leaving G+R- more sensitive; thus, adapting to red will cause subsequently presented test to appear green |
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Term
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Definition
| Parvocellular ganglian cells (in retina) and parvocellular cells (in LGN) |
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Term
| Physiological support for both theories? |
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Definition
| Trichromatic works at receptors (i.e., cones in retina); opponent-process works at parvo ganglion and LGN cells |
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Term
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Definition
| Completely color-blind (black/white/gray world); only requires one wavelength to color match; have only one type of functioning cone (or rods only) |
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Term
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Definition
| Can see colors, but certain colors are confused; only requires 2 wavelengths to make a color match; lacking one cone type |
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Term
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Definition
| Missing L (red) cone; perceives red as yellow/orange |
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Term
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Definition
| Missing M (green) cone; perceives red as yellow/orange |
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Term
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Definition
| Missing S (blue) cone; perceives blue as green |
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Term
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Definition
| Requires 3 wavelengths to make a color match, but sets at different proportions than normals; has all 3 cone types |
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Term
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Definition
| Stability of color perception under varying illuminations; discounting color of light |
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Term
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Definition
| Prolonged exposure to light in a specific part of the visible spectrum, adapting receptors firing to these wavelengths by selectively bleaching a specific pigment (i.e., adapt to light so that bright red becomes neutral) |
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Term
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Definition
| Idea that an object's characteristic color influences our perception (i.e., previous experience) |
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Term
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Definition
| 1) oculomotor - position/movement of eyes; 2) monocular; 3) binocular |
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Term
| Oculomotor & monocular cues |
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Definition
| Oculomotor cues = absolute distance; monocular cues = relative distance (i.e., order of objects, not distance values) |
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Term
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Definition
| Extent to which the two eyes are turned inward during fixation of an object (Ex: more inward = larger angle = closer object); only useful for close objects; also a binocular cue |
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Term
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Definition
| Process by which the eye muscles change the focusing power of the lens by temporarily changing its shape (Ex: thick lens = close = higher focusing power); also a monocular cue |
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Term
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Definition
| Pictorial cue in which one object hides or partially covers another object from view, causing the hidden object to be perceived as being farther away |
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Term
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Definition
| Pictorial cue in which objects that have bases below the horizon appear to be farther away when they are higher in the field of view (i.e., lower the base of object, the closer you perceive the object) |
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Term
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Definition
| Pictorial cue in which the shadow of an object is treated as its base; can influence/override relative height cue (see slides) |
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Term
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Definition
| Pictorial cue in which, when two objects are known to be of equal size, the one that is farther away will take up less of the field of view, and vice versa |
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Term
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Definition
| Pictorial cue in which our knowledge of an object's actual size sometimes influences our perception of its distance (Ex: different sized coins) |
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Term
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Definition
| Pictorial cue in which objects that are farther away look more blurred (and bluer) than objects that are closer because we must look through more air and particles to see them |
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Term
| Perspective convergence (vanishing point) |
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Definition
| Pictorial cue in which parallel lines in the distance converge as distance increases (Ex: railroad tracks) |
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Term
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Definition
| Pictorial cue involving the visual pattern formed by a regularly textured surface that extends away from the observer; provides info about distance b/c elements in the gradient appear smaller and more dense as distance from observer increases (and vice versa) |
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Term
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Definition
| Pictorial cue based on the fact that as an observer moves, nearby objects appear to move rapidly whereas far objects appear to move slowly |
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Term
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Definition
| Farther object is covered/uncovered by a nearer object due to sideways movement of the observer related to objects |
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Term
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Definition
| Difference between the retinal images projected on the two eyes (i.e., objects fall on disparate points of the two retinas) |
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Term
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Definition
| Device that presents pictures to the left and right eyes so that the binocular disparity experienced results in a convincing illusion of depth (e.g., 3D glasses, ViewMaster) |
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Term
| Corresponding retinal points |
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Definition
| Points on each retina that would overlap if one retina were slid on top of the other; receptors at corresponding points send signals to the same location in the brain |
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Term
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Definition
| Imaginary circle that passes through the point of fixation (on fovea); images caused by a visual stimulus on this surface fall on corresponding points on the two reintas |
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Term
| Non-corresponding (disparate) points |
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Definition
| Objects that do not fall on the horopter and would not overlap if the retinas were slide onto each other |
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Term
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Definition
| Visual angle between the images of an object on the two retinas; zero for corresponding points; with images that fall on non-corresponding points, the angle of disparity = the degree of non-correspondence; closer objects have larger angle of disparity, and vice versa |
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Term
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Definition
| Object is closer than horopter; images fall outward towards the sides (ears) |
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Term
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Definition
| Object is beyond the horopter; images fall inward towards nose |
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Term
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Definition
| Perception of relative distance (depth) of objects from binocular disparity |
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Term
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Definition
| Pair of stereoscopic images made of random dots; ability to perceive depth provides evidence that we use binocular disparity to perceive depth, even in the absence of monocular cues |
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Term
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Definition
| Perceived size influenced by perceived depth (distance); objects can take up the same amount of space in visual field (same retinal size), so monocular and bipolar cues are needed |
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Term
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Definition
| Quantified in degrees of visual angle and influenced by size of object and distance at which the object is viewed |
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Term
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Definition
| Size and distance of test stimulus varied together such that retinal size always equals 1 degree (same retinal size, but different physical sizes & distances); size of comparison matched to test size |
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Term
| Holway-Boring implications |
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Definition
| The fewer depth cues available to us, the less accurate we are at judging physical sizes of objects; in the absence of depth info, perceived size is based on retinal size (i.e., sun and moon) |
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Term
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Definition
| We generally perceive sizes of objects correctly, despite changes in viewing distance (and thus retinal size) |
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Term
| Size-distance scaling equation |
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Definition
| S=RxD; S = perceived size, R = size of retinal image, D = perceived distance to object |
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Term
| Size-distance scaling illusions (4) |
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Definition
| Muller-Lyre, Ponzo (railroad), Ames' room, moon illusion |
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Term
| Functions of motion perception (5) |
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Definition
| 1) surviving predators & catching prey; 2) exploring 3D-ality; 3) separating objects/background; 4) provides info about distance (motion parallax) and direction of heading; 5) postural control |
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Term
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Definition
| Patterns of retinal motion generated as one moves through the world; forward/backward movement causes expanding/contracting optic flow |
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Term
| Postural control & vestibular sense |
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Definition
| Visual info can override vestibular cues (feel movement in IMAX movies) or conflict with them (motion sickness) |
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Term
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Definition
| Effect of brain damage (in MT) in which the ability to perceive motion is disrupted; can result in deficits in self-locomotion, pouring liquids, social interaction, etc. |
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