This volume surveys the way that understanding of the minds of animals and ideas about the relationship between animal and human behaviour developed from around 1870 to 1930. In describing the research and theories which contributed to these developments, this book looks at the people who undertook such studies and the reasons why they did so. Its main purpose is to examine the different ways in which the outcome of this work affected their ideas about the human mind and exerted such a formative influence on psychology in general.