The general aims of physiological psychology research are set out. It is argued that theoretical accounts of behavioural mechanisms that ignore physiological findings may be in danger of being irrelevant. There are inherent methodological difficulties in conducting brain and behaviour research, but these are not insuperable and are sometimes misinterpreted. Progress is made generally when a number of different technical approaches can converge on the same question. Aside from the advantages of pursuing brain and behaviour work for the understanding of basic mechanisms, some possible practical benefits are discussed, especially in the context of scientific financial policy. Two broad classes of possible therapeutic procedures for treatment of brain damage are discussed.