Sensation can be described as the process of how our nervous system and sensory receptors receive and translate stimuli from our environment. Perception is the process by which our brains organize and interpret sensory stimuli, which allows us to recognize significant events and objects. Sensation functions as a bottom-up process because it starts at a smaller level and works its way up (i.e. from sensory receptors to processing centers). Perception functions as a top-down process because it starts at a larger level and gets smaller as it continues (i.e. from the sensory input down to our expectations and experiences).

Rods (which detect black and white) and cones (which detect colors) are both located in the retina, which lines the back of the eye. After the rods and cones detect visual stimuli the information is relayed to the brain via the optic nerve, which exits the eye via the optic disc. There are no photoreceptors on the optic disc, resulting in our blind spot.

EEG (electroencephalogram) involves the placement of electrodes on a person's scalp to detect brain waves, specifically when the subject is asleep.

Rods and cones are the light-sensitive receptor cells that are responsible for transducing light waves into neural impulses.

Sensory adaptation is a gradual decline in sensitivity to prolonged stimulation. Senses—in this case taste—will automatically adapt to decline their sensitivity to stimulation over time. Habituation is a closely related concept that involves less sensitivity over time; however, habituation has to do more with physiological, cognitive, and perceptual processes rather than basic sensory processes. Taste bud cell death does not occur after prolonged stimulation.

Autokinetic illusion is when a single unmoving light in a dark room appears to move when stared at for several seconds. It is not a monocular depth clue.

Interposition refers to the monocular depth clue indicating an objects relative closeness by seeing whether that object is stacked on top of an object, or whether an object is stacked on it.

Relative size refers to objects farther away appearing smaller.

Shadow (or shading) refers to closer objects reflecting more light, and thus appearing less dark, than objects further away.

Action potentials are caused when different ions cross the neuron's membrane. The inside of the neuron becomes more positive due to the rush of sodium into the cell during depolarization. This raises the membrane potential from resting (roughly ) to the threshold level of about , which triggers the action potential and raises the membrane potential to roughly .

Following the action potential, potassium exits the neuron to reduce the membrane potential before the sodium-potassium pump restores the resting potential.

Top-down processing uses larger context to assume smaller bits of missing information. Bottom-up processing is the opposite - using small bits of information to understand a bigger picture. Signal detection theory is the ability to choose between and identify stimuli. Perceptual constancy refers to the tendency in humans to see familiar things as having similar shapes, colors, and sizes, in spite of changes that may have occurred in that object.

The periphery of the retina contains many more rods than cones. Rods allow people to easily detect changes in light, and cones allow us to see in color and are located in the center—fovea—of the retina where visual acuity is best. Rods might not help us with seeing things super accurately, but they do help us with detecting motion because of the changes in light. The blind spot is where the bundle of nerves at the rear of the eye chamber block incoming light to hit the retina; thus, creating a "hole" in our vision. Nearsightedness has to do with visual acuity based on distance from the object, not peripheral vision.

Olfactory neurons come in direct contact with the stimuli. They also are directly in the brain. Other sensory receptors transmit information to a separate neuron that relays the information to the brain.