In the US, clinical psychologists were working as assistants to psychiatrists even before the start of the Second World War, helping them with psychological testing of patients, as well as assisting them in understanding the patient's personality and mental state.
在第二次世界大戰之前，美國開始發展出臨床心理師來扮演輔助精神科醫師的角色，主要是提供他們實施測驗、了解病人病情、性格等的服務。