Transduction is the conversion of energy from one form to another. In the context of psychology and sensation, it refers to the conversion of information carrying energy from the environment into information carrying electrical energy within the nervous system. In vision, this involves the conversion of light into electrical energy. This occurs in the retina of the eye, when photopigments break down in the presence of light, and trigger responses in photoreceptor cells, that then transmit the electrical energy to the brain. Ganglion cells also lie within the retina, but these do not play a role in transduction. The pupil allows light to enter the eye and reach the retina, but is not the location of transduction. Neither is the cornea—the outer layer of the eye—nor the optic nerve, which carries information from the retina to the visual cortex.

The fovea is the location of the highest concentration of cones. The cones are the photopigment responsible for color vision, and are associated with high acuity vision. This is relative to rods, which are sensitive under low light conditions, but which do not produce highly accurate visual detail. As the fovea has the highest concentration of cones, it is also the area of greatest visual acuity on the retina. This area is centrally located on the retina, and corresponds to the focus of one's gaze. In other words, the light from any object one focuses on will be falling upon the fovea. This is why our visual acuity is greatest at the center of our visual field. Although the fovea is located on the retina, it would be redundant to describe 'the retina' as the location of the greatest visual acuity, as the retina is the only body organ capable of transducing visual information. The optic nerve exits the eye through an area devoid of photoreceptors, known as the blindspot. This area in fact processes no visual information, and is an incorrect choice. The ciliary muscles are responsible for changing the shape of the lens. These do not contribute to transduction. Last, the cornea is the outer layer of the eye. It does not contribute to transduction.

Blindsight is a phenomenon wherein an individual is unable to consciously perceive visual stimuli due to cortical blindness, but nonetheless possesses healthy eyes. Individuals evidencing blindsight will be able to correctly guess about basic visual conditions in their environment (i.e. in a laboratory setting) at a higher success rate than could be accounted for by chance alone. These individuals will not report any conscious experience or awareness of the visual details they are 'guessing', and will believe they are simply guessing blindly. It is believed that in these cases, an older component of the visual system, dating back to the reptilian brain and not available to consciousness, is contributing to these "guesses." Anton-Babinski syndrome is a condition in which an individual with cortical blindness will report confabulated visual experiences, and deny their lack of vision. The remaining two answer choices are fictitious and incorrect.

Abnormalities in the shape of the eye are the cause of all of nearsightedness, farsightedness, and astigmatism. Typically nearsightedness and farsightedness are caused by irregularities in the lens of the eye. This causes light to improperly be focused relative to the retina. As a result, either near or far images will appear out of focus, due to the improper adjustment of the lens. In the case of astigmatism, the cornea as well as the lens may be implicated, in which case the an abnormality in the curvature of this front portion of the eye contributes to blurry vision. All of these defects may be corrected by LASIK, or corrective lenses. Damage to the nervous system or the visual cortex would lead to partial or total cortical blindness, not to these conditions. Though some psychological disorders are implicated in visual deficits, they do not play a role in these three.

The Ishihara test is a diagnostic tool for assessing deficiencies in color vision. It presents tester takers with numbers formed out of colored circles. These numbers are set against a background formed of further colored circles, in hues paired to assess color blindness. If the tester is unable to distinguish the number from the background, then they likely suffer color blindness. The test examines red-green color blindness. The test does not determine auditory acuity. Likewise it does not assess attention to stimuli, nor the ability to discriminate between changes in a stimulus.

Saccades can occur voluntarily or involuntarily. The voluntary saccades allow you to rapidly change fixation from one object to another. This action allows you to read by rapidly changing your fixation on different words and locations on the page. Vergence is when two eyes move in the opposite direction, this would not allow you to focus on the words on the page, making reading impossible (trying to read while "crossing" your eyes). Smooth pursuit is when the eyes smoothly follow a moving object, words on a page are stationary in most situations. Reflexive eye movements are involuntary whereas reading is a voluntary action. 

The magnocellular system is colorblind and it carries low spatial frequency information and high temporal frequency information in the more dorsal regions of the posterior half of the brain. This means the visual information it carries is about large, fast things leading to the processing of information about location. The other answer options pertain to the parvocellular system.

Glaucoma is caused by pressure due to the blockage of flow of aqueous liquid. Therefore, detection of pressure build-up before it damages the optic nerve head is the correct prevention method. Injection of anti-vascular drugs is used for Macular degeneration that is detected early enough. Control of your diet and blood pressure may delay peripheral degeneration and diabetic retinopathy. Antibiotics and hygiene can prevent blindness caused by Trachoma.

Gestalt principles are common sense principles for explaining why we see what we see. Simplicity is the common sense principle that the simplest shape is usually the right explanation for an image. Synchrony is the principle defined as features that appear and disappear at the same time belong together. Connectedness is the term for the principle that connected feature belong together. Proximity is the Gestalt principle for things that are close together belong together, and similarity is the principle that things that look alike probably come from the same source.

The Opponent/Process Theory is defined as three types of receptor cones in the retina for color processing, each handling a different pair of colors, when only one can fire at a given time. This is used to explain color blindness—only one color in a pair fires appropriately—and afterimages.