Kinsey’s research went beyond theory and interview to include observation of and participation in sexual activity, sometimes involving co-workers. Kinsey justified this sexual experimentation as being necessary to gain the confidence of his research subjects. He encouraged his staff to do likewise, and to engage in a wide range of sexual activity, to the extent that they felt comfortable; he argued that this would help his interviewers understand the participants’ responses. Kinsey filmed sexual acts which included co-workers in the attic of his home as part of his research; Biographer Jonathan Gathorne-Hardy explains that this was done to ensure the films’ secrecy, which would have caused a scandal had it become public knowledge. James H. Jones, author of Alfred C. Kinsey: A Public/Private Life, and British psychiatrist Theodore Dalrymple, among others, have speculated that Kinsey was driven by his own sexual needs.