chapter summary from 6-11 and short answer questions with answers!

17 Pages
Unlock Document

Matthias Niemeier

Chapter summaries 6 1. Reconstructing a three-dimensional world from two, non-Euclidean, curved, two- dimensional retinal images is one basic problem faced by the brain. 2. Having two eyes has a number of advantages, some of which have to do with depth perception. However, it is important to remember that it is possible to reconstruct the three-dimensional world from a single two-dimensional image. Two eyes have other advantages over just one: expanding the visual field, permitting binocular summation, and providing redundancy if one eye is damaged. 3. A number of monocular cues provide information about three-dimensional space. These include occlusion, various size and position cues, aerial perspective, linear perspective, motion cues, and accommodation. 4. Having two laterally separated eyes connected to a single brain also provides us with important information about depth through the geometry of the small differences between the images in each eye. These differences, known as binocular disparities, give rise to stereoscopic depth perception. 5. Random dot stereograms show that you dont need to know what you are seeing before you see it in stereoscopic depth. Binocular disparity alone can support shape perception. 6. The difficulty of matching an image element in one eye with the correct element in the other eye is known as the correspondence problem. The brain uses several tricks to solve the problem. For example, it reduces the initial complexity of the problem by matching large blobs in the low-spatial-frequency information before trying to match every high-frequency detail. 7. Single neurons in primary visual cortex and beyond have receptivefields that cover a region in three-dimensional space, not just the two-dimensional image plane. Some neurons respond to a wide range of depths (e.g., stimuli beyond the current distance of fixation). Others have more precise receptive fields. 8. When the stimuli on corresponding loci in the two eyes are different, we experience a continuous perceptual competition between the two eyes known as binocular rivalry. 9. All of these various monocular and binocular depth cues are combined (unconsciously) according to what prior knowledge tells us about the probability of the current event. Making the wrong guess about the cause of visual input can lead to illusions. Study questions: What is the advantage in binocular summation? The advantage in binocular summation is that detecting a stimulus can be done with two eyes, as opposed to just one, and so this yields more information about the stimulus. Explain the difference between a monocular depth cue and a binocular depth cue. A monocular depth cue is available when the world is viewed with one eye alone. A binocular depth cue relies on information from both eyes. www.notesolution.comWhat is the idea behind positivism? Positivism is a philosophical position arguing that all you really have to go on is the evidence of your senses, so the world might be nothing more than an elaborate hallucination. Monocular Cues to Three-Dimensional Space Name three monocular cues. 1) Occlusion 2) Relative size cue 3) Texture gradient. Explain what is meant by texture gradient. Texture gradient is a depth cue based on the geometric fact that items of the same size form smaller images when they are farther away. Thus, an array of items that change in size across the image will appear to form a surface in depth. What kind of information does an aerial perspective provide about the stimulus? An aerial perspective is a depth cue that is based on the implicit understanding that light is scattered by the atmosphere. More light is scattered when you look through more atmosphere. Thus, more distant objects are subject to more scatter and appear fainter, bluer, and less distinct. An aerial perspective provides information about the relative distance of objects from the observer What is a vanishing point? A vanishing point is the apparent point at which parallel lines receding in depth converge. What kind of movement does the motion parallax depend on? Explain. Motion parallax depends on the viewers head movement. The geometric information obtained from an eye in two different positions at two different times is similar to the information from two eyes in two different positions in the head at the same time. What is a pictorial depth cue? A pictorial depth cue is a cue to distance or depth used by artists to depict three-dimensional depth in two-dimensional pictures. How are convergence and divergence important to depth perception? Convergence and divergence are important to depth perception because they are used to place the two images of a feature in the world on corresponding locations in the two retinal images (typically on the fovea of each eye). They both reduce the disparity of that feature to zero, or nearly zero. Binocular Vision and Stereopsis Explain the concept of corresponding retinal points. Corresponding retinal points are points on the retina of each eye where the monocular retinal images of a single object are formed at the same distance from the fovea in each eye. The two foveas are also corresponding points.
More Less

Related notes for PSYB51H3

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.