In this article, the author adopted a lot of data from psychology studies into the discussion of effective visual design. This might be because visual design is deeply related to the study of psychology. When people see designs, they need a lot of steps such as perceiving objects, analyzing it, and understanding the meaning. In other words, visualizing design is a big mental activity, a main part of psychology study. Errey, Ginns and Pitts (2006, p. 7) also state that designers can work more effectively if they can understand the principles of cognitive psychology when designing user experiences. Therefore, it is necessary to take account of psychological theories in the discussion of visual design.
Errey, C., Gins, P., & Pitts, C. (2006). Cognitive load theory and user interface design: making software easy to use. Retrieved from http://www.ptg-global.com/PDFArticles/Cognitive%20load%20theory%20and%20user%20interface%20design%20Part%201%20v1.0.pdf