This report supports the guidance on the use of behavioural markers to support non- technical skills in oil and gas operations contained in IOGP Report 503. It is aimed at personnel in IOGP member companies who have a need for a deeper understanding of the scientific and technical background to the guidance published in Report 503. It summarizes a number of considerations behind the content of Report 503, including learnings from the scientific literature and existing industry guidance on the use of behavioural markers in Crew Resource Management applications. It also draws on experience gained during the preparation of IOGP Reports 501 and 502. It was been prepared and released separately from Report 503 to keep the recommendations in 503 as clear and simple as practical.