The major effect on science in the Enlightenment was the insistence of verification of scientific observations through the scientific method. Before the enlightenment, scientific knowledge was considered to be based on what expert said, very much like saying "If the Bible said it was so, it was so". Doctors used the books of Galen and others to perform surgeries and for their knowledge of the human body, but their charts were often based upong dissections of animals and extrapolations to humans, so they were very inaccurate. That is why Michelangelo dug up recently dead bodies to learn musculature for his paintings. It was assumed that the objects in the heavens acted according to some ancient system, until Copernicus and Galileo determined how the solar system acted through observations and mathematics.
These feelings are what guided Wundt's attempts in the 1880s to found experimental psychology. Since the beginning of psychology, there has been an effort to make observations more objective so that results can be replicated and the scientific method could be followed.