The visual cortex automatically merges the two images

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The visual cortex automatically merges the two images into one, enabling us to perceivedepth-Convergenceis the inward turning of our eyes that is required to focus on objects that areless than 50 feet away from us, this is important binocular depth cue that requires botheyes to work-The visual cortex uses the size of the convergence angle between the eyes to judge theobjects distance-Accommodationhelps determine depth and is only effective at short viewing distances-Best cues to depth occur when both eyes work together, we are able to see depth evenwhen one eye is closed-Monocular depth cuesare depth cues that helps us perceive depth using only one eye
The Visual WorldPerceiving Motion-The brain perceives motion partly from the changing size of an image on the retina and inpart from the relative brightness of objects-Beta effectrefers to the perception of motion that occurs when different images arepresented next to each other in succession (In the beta effect, our eyes detect motion froma series of still images, each with the object in a different place. This is the fundamentalmechanism of motion pictures (movies). In the phi phenomenon, the perception of motionis based on the momentary hiding of an image)-Phi phenomenonis when we perceive a sensation of motion that is caused by theappearance and disappearance of objects that are near each other-The beta effect and phi phenomenon are examples of the importance of the gestalt —which our tendency to see more than the sum of the partsKey Take Aways-Vision is the process of detecting the electromagnetic energy that surrounds us. Only asmall fraction of the electromagnetic spectrum is visible to humans-The visual receptor cells on the retina detect shape, colour, motion, and depth-Light enters the eye through the transparent cornea and passes through the pupil at thecentre of the iris. The lens adjusts to focus the light on the retina, where it appears upsidedown and backward. Receptor cells on the retina are excited or inhibited by the light andsend information to the visual cortex through the optic nerve-The retina has two types of photoreceptor cells: rods, which detect brightness and respondto black and white, and cones, which respond to red, green, and blue. Colour blindnessoccurs when people lack function in the red- or green-sensitive cones-Feature detector neurons in the visual cortex help us recognize objects, and some neuronsrespond selectively to faces and other body parts-The Young-Helmholtz trichromatic colour theory proposes that colour perception is theresult of the signals sent by the three types of cones, whereas the opponent-process colourtheory proposes that we perceive colour as three sets of opponent colours: red-green,yellow-blue, and white-black-The ability to perceive depth occurs as the result of binocular and monocular depth cues-Motion is perceived as a function of the size and brightness of objects. The beta effect andthe phi phenomenon are examples of perceived motion

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Term
Winter
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Photoreceptor cell

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