This chapter considers how functional imaging methods work, focusing in particular on functional magnetic resonance imaging (fMRI). Whereas structural imaging measures the permanent characteristics of the brain, functional imaging is designed to measure the moment-to-moment variable characteristics of the brain that may be associated with changes in cognitive processing. Electrical and chemical activity of neurons leads to changes in the blood flow, termed the haemodynamic response. This is detected by fMRI and related techniques (e.g., fNIRS, functional near-infrared spectroscopy). The chapter focuses on methodological factors that are important in ensuring that the results obtained can indeed be meaningfully linked to cognitive theory. It discusses how functional imaging data are analyzed to find regions of activation and considers some of the pitfalls in their interpretation. It also discusses multi-voxel pattern analysis which does not rely on overall activation levels but on a pattern of activity in a given region.
