Module 18 Study Guide Questions

Trace the path of light through the eye as it enters the cornea, is transducer into neural energy, and ends in the visual cortex of the occipital lobes.

1. Enters Cornea, which bends the light 2. Light passes freely through pupil in the iris 3. Light passes through victorious humor. 4. Retina captures light rays, processes them into impulses 5. Impulses sent to optic nerve via nerve fibers 6. Optic nerve transmits message to the brain. 1.Light enters and travels though the cornea 2.Goes through the aqueous humor behind the cornea to the pupil 3. Goes through the lens which is controlled in thickness by the muscles 4. Goes through vitreous humor and hits the retina 5. The rods and cone cells of the retina are stimulated sending the information out through the optic nerve. 6. The optic nerve sends the message to the optic chi as a to the optic tract 7. The optic tract delivers the message to the primary visual cortex of the occipital lobe.

Describe the function of each of the following parts of our visual system: Cornea, Pupil, Iris, Lens, Retina, Rods and Cones, Bipolar Cells, Ganglion Cells, Optic Nerve, Blind spot, Fovea

Cornea: Protects eye and bends light to provide focus Pupil: Adjustable opening in the center of the eye through which light enters Iris: Ring of muscle tissue forming the colored portion of the eye Lens: Transparent structure behind the pupil that changes shape to help focus images on the retina Retina: Light sensitive inner surface of the eye that begins the processing of visual information Rods: Retinal receptors that detect black, white, gray, and necessary information; necessary for peripheral and twilight vision when cones don't respond Cones: Retinal receptor cells that are concentrated near the center of the retina and that function in daylight or well-lit conditions; the cones detect fine detail and give rise to color sensations Bipolar Cells: Transmit the signals from the photoreceptors or horizontal cells, and pass it onto the ganglion cells Ganglion Cells: Process visual information that begins as light entering the eye and transmit it to the brain via their axons Optic Nerve: The nerve that carries neural impulses from the eye to the brain Blind Spot: The point at which the optic nerve leaves the eye creating a "blind" spot because there are no receptor cells located there Fovea: The central focus point in the retina, around which the eye's cones cluster

Explain the location and function of feature detectors.

Nerve cells in the brain that respond to specific features of the stimulus. They are neurons in the brain that respond to specific aspects of a stimulus: Edges, Lines, Angles, Movements. Feature detectors in the visual cortex send signals to other areas of the cortex for higher-level processing.

Define parallel processing and discuss its role in visual information processing.

Parallel processing is the brain's natural mode of information processing, in which it handles many aspects of a problem simultaneously. This multitasking ability lets the brain distribute subdimensions of vision (color, movement, depth, and form) to separate neural teams that work separately and simultaneously. Other neural teams collaborate in integrating the results, comparing them with stored information, and enabling perceptions. Our brains process multiple features of visual experience at once and integrate these features to create our experience of vision.

Explain why human vision has a blind spot.

The blind spot is a region on the retina where ganglion cells connect with the optic nerve, there are no receptors in this area so nothing can be translated into vision. We are often unaware of this spot because the two blind spots in each eye do not overlap (and our eyes in those spots with the surrounding environment/patterns) - Draw a cross and a circle side by side on a sheet of paper. Focus on the cross. Close one eye and slowly bring the paper towards your face, the circle will disappear at a certain point.

Describe the two characteristics of visible light and explain how they determine our awareness of hue and intensity.

Wavelength - determines hue (color) Amplitude - Intensity (amount of energy in light waves)=determines brightness

Compare and contrast the Young-Helmholtz trichromatic theory and the opponent-process theory on color vision.

Young-Helmholtz Trichromatic theory: We have 3 types of cones in our retina. They detect RED, BLUE, and GREEN. From a combination of those three colors we see everything. The issue is that it does not do a good job explaining color blindness or after images Opponent-Process Theory: We have 3 types of receptor cones and they each handle a par of colors (red/green, yellow/blue, and black/white). If one sensor/color is firing it slows the other from firing. Theory does a good job of explaining afterimages. Your cones, after firing red for awhile, will rest and fire the opposite green, when not being stimulated. It also explains color blindness well. Most people who have trouble seeing colors cannot see either tints or red/green or blue/yellow. Each theory describes physiological mechanisms in the visual system. Trichromatic theory explains the responses of the cones in the retina. Opponent-process theory explains neural response for cells connected to the cones further in visual pathway.