2 The breadth of psychological research
2.1 An evidence-based enterprise
We have seen that psychology is an evidence-based enterprise and we have also seen that disputes about what should count as evidence have had an important impact on the development of psychology as a discipline. For example, the rise of behaviourism was driven by the idea that only observable behaviour is legitimate data for psychology because only data that can be observed by others, and agreed upon, can be objective. Many other disciplines have had less trouble with this issue, partly because they have fewer choices about which methods to use, what kinds of data to collect and what kinds of evidence to accept. Think, for example, of mechanical engineering, chemistry or geology and compare these with psychology. The range of choices open to psychologists arises from the complexity of their subject matter – understanding and explaining humans and, to a lesser extent, other species.
Psychology is unusual because its subject matter (ourselves) is not only extremely complex but also reactive, and because we are inevitably involved in it, personally, socially and politically. This involvement is part of what fuels debates about how to do psychology and what counts as legitimate data.
This section will give some examples of how the unusual nature of psychology as a subject influences the practice of research. We shall look at the impact of our ‘involvement’ on how research questions are formulated, at the various kinds of evidence that could be used, and at the range of methods that are available to collect the evidence and to evaluate findings.