People studying perception could begin with theories on how the human mind organizes stimuli, as seen in the Gestalt Laws of Perceptual Organization. These laws explain that elements close together and similar will be grouped together, that they are usually grouped to form complete figures in their simplest interpretation and that "regions bound by symmetrical borders tend to be perceived as coherent figures."
One topic that is both sensory and perceptual is the evolution of organic vision. Components of this discussion include analyzing single- and multi-lens eyes, determining how they function and differ, along with how the shape and color of objects help us classify and group them, and exploring the two types of visual systems found within human eyes: scotopic and photopic vision. You can learn about the 10 layers of the retina, how the eyes and brain communicate and correlate to produce vision and the visual projection and association areas.
Illusions are a cornerstone of many extensive explorations of scenes and perception. As explained by G. Scott Owen, professor emeritus at George State University, "Illusions are produced when we are presented with an impoverished visual environment that eliminates the normal redundancy and overloads or deliberately misinforms a single functional system." This results in a person's perception that contradicts the physical facts of what she perceives. Topics on illusions include explaining linear perspective, interposition, height in the plane, light and shadow, relative size, textural gradients and relative motion parallax.
There are two dominate theories on how humans process and see color. The trichromatic theory of color vision states there are three classes of cone receptors in the eye and each is more likely to be sensitive to a different primary color. The opponent processing theory states that color perception is led by dueling mechanisms: the red-green and the blue-yellow. Under this theory, each mechanism has a color that excited it and one that inhibits it; opponent neurons interpret these mechanisms and wavelengths to show different color combinations at different times. Color psychology is a topic in discussions of perception that refers to how different colors are thought to have shared meanings among most people without them realizing it. Exposing people to particular colors and color combinations at particular times is used as therapy, as a marketing strategy and in the creation of visual art.