This chapter focuses on two schools of thought within psychology that offer explanations for the interaction between humans and their environments: information-processing theory and social judgment theory. It also focuses on theories of aesthetic preferences toward natural environments. The book examines a variety of perceived environmental quality indicators for measuring values, and discusses their validity, reliability, and susceptibility to biases. Psychology yields some insight into how people experience and understand scenic environments and how they form and express their values. Social judgment theory is less global in its attempt to explain perception and evaluation than information-processing theory. The evaluation elements in the system are form, color, line, and texture, and the relative weights for each element may be equal or variable. Perceived environmental quality indicators can help governments avoid losing sight of the overall public interest due to the tunnel vision of experts.