Prosopagnosia can be either congenital or acquired. Congenital cases are more rare, and the most difficult to treat. Acquired prosopagnosia usually results from damage to the occipito-temporal lobe. The fusiform gyrus has been shown to activate in response to faces in several different neuro-psychological studies. This disorder is famously chronicled in the novel "The Man Who Mistook His Wife for a Hat" by Oliver Sacks.

Our brains use the differences in the location of an object on our retinas in order to judge their relative distance from one another. This requires two eyes, and thus is binocular. The other cues listed require only one eye (monocular).

Gate-control theory posits that the spinal cord contains a "gate" that controls whether pain signals get sent to the brain or not. This "gate" is opened based on the strength of the pain signals from the body. 

Figure-ground is a perception used to distinguish a figure from its background, whether that be black words on a white page or distinguishing a particular voice from a crowd. There are many cues that enable us to distinguish a figure from its background, like color, shapes, edges, movements, or sounds. Figure-ground perception is a part of “Gestalt principles," or the prcoess of evaluating the bigger picture.   

Justin can physically speak, so we can rule out Broca's area, which is in the frontal lobe. However, he is unable to understand language, which is handled by Wernicke’s area. Wernicke’s area is located in the temporal lobe.

Retinal disparity is a binocular cue that involves observing the difference between the two images the retinas receive of a single object. The greater the difference, the closer the object is to the viewer.

The retina captures external light and converts it into visual images that are sent to the brain. The retina contains rods, which detect black and white, and cones, which detect color.

Transduction occurs when sensations are perceived. In the case of touch, our fingers detect pressure which is translated into a neural impulse, causing our brain to perceive that we have made contact with a surface.

Proximity, closure, similarity, and continuity are four of the Gesalt rules for perception, whereas difference (the opposite of similarity) is not. Proximity states that groups of objects close together are likely to be grouped together, closure is the tendency to fill in the gaps in a visual scene, similarity describes how objects that look similar are likely to be grouped together, and continuity states that objects with similar orientations are likely to be grouped together.

Figure-ground is one tool our brains use to form perception. This is the organization of the visual field by separating an object (figure) from its surroundings (ground). In this scenario, the apple stands out from the grapes it's surrounded by; therefore, this would make the apple the figure and the grapes the ground. Another example would be a lead singer versus the rest of a band. The lead singer stands out as a separate object, making this individual the figure. The rest of the band would be considered the ground relative to the lead singer.