Placebo Influence of Expectation and Time of Day on Human Cognitive Performance

Abstract

This study used quantitative survey methodology to determine how human circadian chronotype and attitudes and beliefs about potential time-of-day performance influences psychomotor vigilance. Individuals recruited via Amazon Mechanical Turk were surveyed about their sleep-wake behaviors and their beliefs about their psychological well-being and abilities. Respondents also were asked to take part in a psychomotor vigilance assessment during an early afternoon session, and an evening session, to assess time-of-day specific cognitive performance. It was expected there would be a main effect of expectation upon cognitive performance/vigilance. In the proposed study, we predict that the difference between people who expect to perform well, versus expect to perform poorly based on their chronotype-specific behavioral information, even if they are told they are the opposite of how they actually score, will significantly influence how they perform on a cognitive task. Finally, differences in their chronotype were examined based on perceived stress, age, and suggestibility. To date, no other studies have specifically evaluated the influence of expectation as placebo in chronotype cognitive performance. This study will build towards greater understanding of the impact of expectation upon subsequent performance. Individuals were recruited using a convenience sample (N=100) and self-reported their chronotype, perceived stress, suggestibility, and psychomotor vigilance (RT). Although more data is needed to draw significant conclusions based on these hypotheses, overall, this study was the first to attempt to demonstrate perceived benefits of priming expectation for cognitive performance may override chronotype patterns. Thus, the current work may inform the development of education materials to increase awareness of expectation as an intervention for cognitive flexibility, and advance further research about the malleability of circadian systems to psychological influence.