Final answer:
Psychologists have used the process of habituation to test whether newborns can visually discriminate between shapes and colors.
Step-by-step explanation:
In order to test whether newborns can visually discriminate between various shapes and colors, psychologists have made use of the process of habituation. Habituation is a simple form of learning in which an animal stops responding to a stimulus after a period of repeated exposure. In this case, newborns are repeatedly exposed to different shapes and colors, and if they stop responding to certain stimuli, it indicates that they are unable to visually discriminate between them.