Neuroeconomics is still a relatively young field of research and connects the concepts of neuroscience, economics and psychology in order to better understand how people actually make decisions. It seeks to understand the neurological mechanisms behind economic behaviour and how they influence consumer purchasing decisions. Neuroeconomics provides useful insights into a number of disciplines such as marketing, finance, and public policy by exploring the complex connections between the brain and economic decision-making. The assumption that normative economic models do not fully represent the complexity of human decision-making is at the heart of neuroeconomics. Neuroeconomics scientists use a number of tools such as magnetic resonance imaging (MRI) and positron emission tomography (PET) to observe blood flow and activity in different areas of the brain, and they use blood or saliva tests to measure neurotransmitter and hormone levels.