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).

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 situation with Angela is the best example of synesthesia—a phenomenon, in which stimulation of one sensory pathway triggers a response by a different, unrelated sensory pathway. People with synesthesia might see a certain color whenever they taste a certain food. The important thing to note is that in synesthetic perception, the person experiences the synesthetic connection as being projected outside the body, not just in the mind’s eye (e.g. Angela does not simply imagine the color red when she sees the letter A: she actually sees A as being colored red, even if it is printed in plain black font). The other situations described in the answer choices reflect other psychological phenomena. Ashley is experiencing amnesia; George, phantom limb syndrome; and Taylor, taste aversion.

The Gestalt laws of perception are a set of principles that govern the way humans tend to perceive visual stimuli as a collective whole, rather than discrete individual objects or events. Different names are given to the specific applications of this overarching principle. For example, the phi phenomenon refers to the tendency to perceive a series of lights blinking on and off down a line as a single light moving along, instead of a number of lights turning on and off for no apparent reason. The law of prägnanz (not the prägnanz effect that was listed as an answer choice) is the Gestalt law that suggests that people perceive visual stimuli in terms of the simplest explanation or form possible. Opponent-process theory is a concept of visual perception that explains why some colors seem to be incompatible (e.g. we might see a yellowish green, but we cannot really imagine a reddish green).

“Retinal disparity” is a binocular depth cue, not a monocular cue. The other answers—relative size cue, texture gradient, and linear perspective—are all monocular cues.

A big part of the way humans learn is by starting with a very general concept, and then organizing more detailed concepts within that general paradigm. This means that concepts we have learned before can influence new ideas and concepts that we are learning. When reading a sign, you use your previous knowledge of possible words and phrases, and put that together with the sensory knowledge you acquire from the sign.

Gestalt's principles do reference the phenomena of the mind making a whole based on small parts, but generally refers to visual construction as opposed to semantic meaning.

Binocular cues are depth cues that require the use of two eyes. For instance, trying to touch the tip of two pencils together in front of your face may be rather easy to do with both eyes open; however, attempting this task with one eye open is significantly challenging. Retinal disparity is a binocular cue used to perceive depth between two near objects. It does so by comparing the different images from both retinas. Each eye receives different images because they are usually around two and half inches apart. The greater the difference (disparity) there is between the images, then the closer the object will be. The other options would be incorrect because they are defined as monocular cues.

Sensation is best understood as simply the stimulation of sensory organs (in this case sight). Perception has to do with selecting, organizing, and interpreting sensory input in a meaningful way. One can sense the features of a stop sign; however, in order to perceive what a stop sign is, one must interpret what the sensory input means. The visual cortex is the portion of the brain that is most likely to process visual stimuli. Learning might be involved in perception; however, the best answer is "sensation. . . perception."

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.

The trichromatic theory is the oldest theory to explain why and how humans see color. It posits that there are three types of cone receptors in the retina, one type for each of the primary colors (e.g. red, blue, and yellow).