Quiz 4 Vision Study Guide Sensation Perception EXP3202C Lab Class Know qualities of light i e that it is measured according to wavelength that opsins absorb a photon photon A quantum of visible light or other form of electromagnetic radiation demonstrating both particle and wave properties Know the parts of the eye and their function Vision begins in the retina when light is absorbed by rods or cones The retina is like a minicomputer that energy into neural energy The retina sends information to the brain via ganglion cells neurons whose axons make up the optic nerves Retinal ganglion cells have center surround transduces light receptive fields and are concerned with changes in contrast the difference in intensity between adjacent bits of the scene The retina is a light sensitive membrane in the back of the eye that contains rods and cones which receive an image from the lens and send it to the brain through the optic nerve Terms o iris The colored part of the eye consisting of a muscular diaphragm The transparent window into the eyeball A small pit near the center of the macula that contains the The central part of the retina that has a high concentration of surrounding the pupil and regulating the light entering the eye by expanding and contracting the pupil o macula cones o fovea highest concentration of cones and no rods It is the portion of the retina that produces the highest visual acuity and serves as the point of fixation The lens inside the eye that enables the changing of focus The dark circular opening at the center of the iris in the eye where light enters the eye A light sensitive membrane in the back of the eye that contains rods and cones which receive an image from the lens and send it to the brain through the optic nerve The transparent fluid that fills the vitreous chamber in the posterior part of the eye o cornea o lens o aqueous humor o pupil o retina The watery fluid in the anterior chamber of the eye o vitreous humor Know the components of a photoreceptor Know how different opsins are distributed and how they determine what type of light each photoreceptor detects opsin rhodopsin melanopsin chromophore The visual pigment found in rods A photopigment that is sensitive to ambient light Protein that detects the wavelength of light The light catching part of the visual pigments of the retina What are rods and cones and in what type of conditions are they most effective Know the three types of cones and the wavelengths colors they respond to along with how they are distributed across the retina cone color rod A photoreceptor specialized for daylight vision fine visual acuity and A photoreceptor specialized for night vision Rods cannot signal differences in color because they only have one type of photopigment Cones on the other hand have three types of photopigments which help them differentiate between colors Know the different functions of the inner VS the outer segments of photoreceptors Be able to label a graph of the cells in the retina Change Blindness Powerpoint Slide 4 Photoreceptors connect to horizontal cells and bipolar cells Bipolar cells connect to amacrine cells and ganglion cells Synapses within layer via horizontal cells and amacrine cells Know the pathway optic information travels from the retina to the brain You should know the brain structures that receive optic information as well as where information crosses to the other hemisphere The axons of the ganglion cells converge and leave the eye via the optic nerve After the optic chaism visual information is carried via the optic tract The first About half the fibers in the optic nerve cross to the contralateral side of the brain at the optic chiasm synapse the optic tract makes is in the lateral geniculate nucleus of the thalamus which acts as a relay station to project visual information to the occipital lobe aka striate cortex primary visual cortex and area 17 and V1 The striate cortex is made of 6 layers each receiving a different type of information Cells in the striate cortex respond to several different things some respond to lines or edges some to particular angles some to movement and some to faces What is the blind spot optic disc and what is a unique feature of this area Axons of ganglion cells join to form the optic nerve Optic nerve leaves medial to fovea red so blind spot appears lateral to center of vision Be able to answer questions regarding the flicker technique Know how we typically detect change and why the flicker technique results in change blindness For change blindness to occur the change in the scene typically has to coincide with some visual disruption such as a saccade eye movement or a brief obscuration of the observed scene or image When looking at still images change blindness can be achieved by changing a part of the image Flicker Technique o Why does this cause change blindness Typically a change is detected by local motion signals it s easy to notice movement superior colliculus the disturbance e g a flicker overloads this means of change detection the brain is forced to search the scene item by item until the change is detected o Changes to objects that are more important to the picture will be noticed more quickly than changes to objects less important to the scene you re more likely to scan the important objects first What are the monocular and binocular cues involved in depth perception Be able to define at least one example of each Monocular Depth Cues Relative Size of a retinal image A distance cue making the larger of two objects appear closer to the observer However if we know how big an object really is our brains can solve the distance equals object size divided by relative size relationship to determine absolute distances Refers to clearness of distant details under different atmospheric Aerial Perspective conditions If part of object A is covering part of object B A is almost certainly closer to you than B aka Interposition Occlusion The decrease in size and separation of objects as they become Linear Perspective more distant Binocular Depth Cues Convergence Retinal Disparity The eyes rotate inward to focus on closer objects The retinas have two different pictures of the world because they are in different locations in the head
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