How did the behaviourist approach to psychology achieve this dominance and why was the approach eventually supplanted by the information processing / cognitive approach?

Full title: The behaviourist approach to psychology was dominant for much of the first half of the twentieth century. How did it achieve this dominance and why was the approach eventually supplanted by the information processing / cognitive approach? 3000 word essay excluding references, based on the attached PDF file that provided the main points which will have to be expanded. Short reading list is also included, as the starting point