ABSTRACT

In the mid 1950s I nearly ruined the results of my doctoral dissertation at UCLA. The sordid details are available elsewhere (Rosenthal, 1985) but briefly, it appeared that I might have treated my research participants in such a way as to lead them to respond in accordance with my experimental hypothesis or expectancy. All of this was quite unwitting, of course, but it did raise a sobering question about the possibility of interpersonal expectancy effects in the psychological laboratory. If it were my unintentional interpersonal expectancy effect that had led to the puzzling and disconcerting results of my dissertation, then presumably we could produce the phenomenon in our own laboratory and with several experimenters rather that just one. Producing the phenomenon in this way would yield not only the scientific benefit of demonstrating an interesting and important concept; it would also yield the very considerable personal benefit of showing that I was not alone in having unintentionally affected the results of my research by virtue of my bias or expectancy.