Mental imagery:

"In 1883 [Galton] published a book, Inquiries into Human Faculty and Its Development[.] Among [other] things, the book contained a long section on "mental imagery," the first study of this kind anybody had ever done. What Galton was after was very simple. He wanted to know what kind of pictures people carried in their heads, and so he wrote to a number of his scientific friends and asked what they saw when they thought of an object. ("Suppose it is your breakfast table as you sat down to it this morning.") The result of this survey flabbergasted Galton. Most of his friends wrote back that they didn't see anything and asked what in the world he was talking about. After this complete letdown by his fellow scientists, the bewildered Galton turned to "persons whom I met in general society." They made him feel much better.

...

After some more research, Galton found that pictures in the mind's eye are quite common among most people, but highly uncommon among scientists and abstract thinkers in general. He concluded that deep thinkers consider mental pictures a nuisance and get rid of all this imagery by disuse."

Rudolf Flesch