Several popes attempted to improve navigation on the Tiber in the 17th and 18th century, with extensive dredging continuing into the 19th century. Trade was boosted for a while but by the 20th century silting had resulted in the river only being navigable as far as Rome itself. The Tiber was once known for its floods â the Campus Martius is a flood plain and would regularly flood to a depth of 2 metres (6 ft 7 in).
Franz Mesmer started the idea that there is a state similar to sleep that people can experience in more controlled settings. Mesmerism was named after him, and psychologists like James Braid and Freud expanded on his ideas with some more closer to legitimate scientific evidence to develop his ideas into hypnosis.
zoom_in. Martin E.P. Seligman, the psychologist who conceptualized and developed the theory of learned â¦Dutch HeightâKlaas Fopma/Redux. The theory of learned helplessness was conceptualized and developed by American psychologist Martin E.P. Seligman at the University of Pennsylvania in the late 1960s and â70s.