On Shames' Experimenter Expectancy Paradox

Extract

Shames' article (1979) ingeniously attempts to impeach arguments which support the view that a psychologist's experimental results are significantly influenced by the experimenter expectancy effect. This attack is a powerful one in which Shames unveils his “expectancy paradox”: the scientist investigating the influence of the expectancy effect in psychology remains himself subject to any such expectancy effect. Therefore, he argues, “The more substantial is the evidence for the veridicality of experimenter expectancy ... the more suspect it becomes ...” (1979, p. 384). Shames maintains that this paradox is inescapable only if the experimenter expectancy effect is inexorable in any particular research program and is pervasive through the broad spectrum of psychological research. A review of the literature leads him to hold that this effect is neither inexorable nor unquestionably pervasive. “Thus,” Shames concludes, “the expectancy paradox is less pernicious than may have been feared; however, since it is so intimately tied to the experimenter expectancy effect, the spectre of doubt as to the compass of this effect is cast” (1979, p. 387).