The monkey as a psychological subject.

Many species in long-term captivity have tried to kill time by playing friendly games with their warders. In the end, only rhesus monkeys (Macaca mulatta) could tolerate the tedious hide-and-seek games that their human jailers prefer to play. In this article, written many years before the Stockholm syndrome was first described, the author relates how it was eventually discovered which species is most willing to contribute to the development of a genuinely scientific human psychology.