Binocular vision is used to perceive depth. When Brandon looks out into the forest, he uses binocular vision to determine how far away objects are in the forest. He uses the concept of the figure-ground relationship to identify trees and other figures in the forrest as separate from the background. The act of seeing or looking itself requires transduction. Light that hits his eyes undergoes a process called phototransduction in which light is converted to electrical signals which then move through different types of cells. Ultimately these signals are sent to a part of the brain called the occipital lobe where they are converted into an image in the brain.
Brandon's dog begins to growl as a result of natural selection. Dogs who growled at potential predators were more likely to scare away the predator and survive. As a result, the dog growls when it sees a potential predator. When Brandon's dog starts growling, Brandon becomes fearful that there might be something in the forest. As a result of this fear, his body initiates a sympathetic response, releasing epinephrine into the body. This epinephrine acts on the heart and causes his pulse to increase. He also utilizes his peripheral nervous system to increase the strength of his grip on the leash
