What is wrong with imagery questionnaires?

Research evidence is reviewed which shows that the questionnaire method represents a deviant case in imagery research: Whereas experimental techniques consistently produce strong effects for the imagery variable in a large specter of cognitive tasks, research based on imagery questionnaires yields ambiguous and most frequently negative results. Existing explanations of the discrepant findings are critically examined and found to be inadequate. An alternative interpretation is offered, where it is hypothesized that the questionnaire approach to the study of imagery is infected by a serious methodological flaw, due to differences in subjective conceptions of the rating scale employed in imagery questionnaires. Experimental evidence is reported which supports this interpretation.