The response to the first edition of this book was gratifying. Reviewers seemed to agree that the need for such a source existed and that Measuring Behaviour satisfied that need. More than six years have slipped past since Measuring Behaviour first appeared, and the desirability of some changes became apparent. With the passage of time some sections of the first edition – notably those dealing with the technology for recording behaviour – had inevitably begun to show their age. In revising the book, we have taken the opportunity to make a number of changes to the order in which various topics are dealt with, thereby (we hope) making the ideas flow in a more cohesive manner. Some of the sections have been expanded and some entirely new ones added.

Despite our disclaimers in the introduction to the first edition, some reviewers said we should include detailed examples, both to illustrate the general points and to show in particular cases how research methods are selected and used. We have once again ignored their advice, because others – ourselves included – were pleased that we had kept the book concise. We remain convinced that a text book like this benefits from being as succinct as possible, and have therefore resisted the temptation to allow the new edition to burgeon in the cause of comprehensiveness.

We hope Measuring Behaviour will continue to be useful and that this new edition will help a new generation of scientists and students who wish to observe and measure the behaviour of animals and humans, both in the laboratory and in the field.