Experimenter Effects on Pain Reporting in Women Vary across the Menstrual Cycle
Background . Separate lines of research have shown that menstrual cycling and contextual factors such as the gender of research personnel influence experimental pain reporting. Objectives . This study examines how brief, procedural interactions with female and male experimenters can affect experimentally reported pain (cold pressor task, CPT) across the menstrual cycle. Methods . Based on the menstrual calendars 94 naturally cycling women and 38 women using hormonal contraceptives (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:msub><mml:mrow><mml:mi>M</mml:mi></mml:mrow><mml:mrow><mml:mtext>age</mml:mtext></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mn>19.83,</mml:mn></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mtext>SD</mml:mtext><mml:mo>=</mml:mo><mml:mn>3.09</mml:mn></mml:math>) were assigned to low and high fertility groups. This assignment was based on estimates of their probability of conception given their current cycle day. Experimenters (12 males, 7 females) engaged in minimal procedural interactions with participants before the CPT was performed in solitude. Results . Naturally cycling women in the high fertility group showed significantly higher pain tolerance (81 sec,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mi>d</mml:mi><mml:mo>=</mml:mo><mml:mn>.79</mml:mn></mml:math>) following interactions with a male but not a female experimenter. Differences were not found for women in the low fertility or contraceptive groups. Discussion . The findings illustrate that menstrual functioning moderates the effect that experimenter gender has on pain reporting in women. Conclusion . These findings have implications for standardizing pain measurement protocols and understanding how basic biopsychosocial mechanisms (e.g., person-perception systems) can modulate pain experiences.