The essay proposes to reconstruct the main orientations of the methodological debate on pre-test questionnaire strategies and on the analysis of interview processes. In particular, the focus is on two techniques that have been recently getting more attention during conventions of international scientific associations: the cognitive interview and the monitoring of the interviews. A restrictive conception of the interviewer emerges from this reconstruction. In this scenario, although researchers look to improve their questionnaires through evaluations of subjects outside the research (interviewees, panels of experts), the interviewers are mainly controlled, instead of being considered as privileged witnesses of survey issues.