Most of the problems for psychological science dealt with in this book have arisen from fundamental philosophical objections. However, there is also a body of experimental evidence - namely, research on research - to be considered in this chapter, which has contributed to the debate on the appropriateness of the application of scientific methods as used in the physical sciences to psychology. Starting from the assumption of the experiment as itself a social situation, it has cast doubt on the traditional picture of an objective experimenter investigating an inert subject. Following similar discoveries in physics, it has demonstrated that non-interference and independence of the observer and observed are scientific myths. (It is perhaps worth noting in passing that the models of the physical sciences which psychologists have studiedly aped have usually been outdated.) Westland (1978) has drawn an important distinction between objections to psychological science which are of a fundamental, philosophical nature, suggesting that the whole enterprise is misconceived, and those which are merely tactical, implying deficiencies in its actual practice. It is with the latter that this chapter will be primarily concerned. Much of the work has been carried out and reviewed by Rosenthal (see Rosenthal, 1966; Rosenthal, 1967; Rosenthal and Rosnow, 1969), using such methods as reports of experimenters' behaviour by subjects and films of experimenter-subject interactions. We shall begin by considering some of the least plausible candidates for factors influencing the experimental situation.