 Cretien van Campen graphed the number of publications in the period 1780 - 2000 and noticed a revival of synesthesia studies from the 1980s.In the 1980s, as the cognitive revolution had begun to make discussion of internal states and even the study of consciousness respectable again, scientists began to once again examine this fascinating phenomenon.Led by Lawrence E. Marks and Richard Cytowic in the United States, and by Simon Baron-Cohen and Jeffrey Gray in England, research into synesthesia began by exploring the reality, consistency and frequency of synesthetic experiences.