First, for many decades, ‘behaviour’ has provided the most dominant kind of evidence – what people and animals can be seen to do. Behaviour can cover a very wide range of activities. Think about examples such as a rat finding its way through a maze to a pellet of food, a participant in a memory experiment writing down words five minutes after having done a memorising task, a small group of children who are observed whilst they, jointly, use a computer to solve a problem, a teenager admitting to frequent truancy on a questionnaire. Some of these examples are behaviours that are very precisely defined and involve measurements – how fast the rat runs, how many words are remembered. This would be classed as quantitative research (i.e. with measurements and probably a statistical analysis). Other behaviours, such as the children learning to solve a problem using a computer, are less well defined but can be observed and described in detail, qualitatively (i.e. not measured and subjected to statistical analysis), or sometimes quantitatively (for example, when the frequency of particular actions can be counted up). The truancy example involves a self-report about behaviour that is not actually seen by the researcher. These particular examples of behaviours as data come from quite different psychological research traditions which you will learn about in the chapters that follow. The important point here is that behaviour is, in principle, observable – and often measurable in relatively objective ways – from the outside.