A longitudinal study of the effects of experimenter bias on the operant learning of laboratory rats

Training schedules and the E-effect on the acquisition of a two-turn task in a temporal circular maze

“…At the conclusion of this experiment, it was noted that there existed a very strong E effect on the rate of acquisition. A similar E-effect phenomenon has been reported by Rosenthal et al (1963Rosenthal et al ( , 1964, in both discrirnination learning and operant learning situations, and by Brogden (1960), in an avoidance learning situation. SUBJECTS Eighteen male and 18 female experimentally naive hooded rats from the Monash University colony, aged 60-70 days at the commencement of the experiment, were housed individually, with ad lib water, and maintained at approxirnately 80% estimated growth weight throughout the experiment.…”

Teachers' Expectancies: Determinants of Pupils' IQ Gains

“…In studies employing animals, for example, E's led to believe that their rat Ss had been bred for superior learning ability obtained performance superior to that obtained by Es led to believe their rats had been bred for inferior learning ability (Rosenthal & Fode, 1963;Rosenthal & Lawson, 1964). The present study was designed to extend the generality of this finding from Es to teachers and from animal Ss to school children.…”

Reproducibility in Science

“…18 Observer bias has long been recognized to be a problem in preclinical studies and beyond, so this result should not be surprising. 19 Confirmation bias in scientific investigation unavoidably makes even the best scientists prone to try to find results or interpretations that fit their preconceived ideas and theories. 20,21 In addition, empirical assessments of preclinical studies showed an array of problems, including, but not limited to, the fact that there was a failure to repeat experiments, to use legitimate controls, to validate reagents, and use appropriate statistical tests.…”

“…For example, despite the improvements in Guidelines to Authors, and despite the decades-long recognition of the need for investigator blinding, 19 there seems to still be a general reluctance to demand blinding of investigators even when subjective end points are assessed. As with this journal, even the journals that have reworked their Guidelines to Authors still do not demand blinding of investigators in the evaluation of subjective preclinical data.…”