title: Is the effect of aerobic exercise on cognition a placebo effect?
abstract: A number of studies and meta-analyses conclude that aerobic fitness (walking) interventions improve cognition. Such interventions typically compare improvements from these interventions to an active control group in which participants engage in non-aerobic activities (typically stretching and toning) for an equivalent amount of time. However, in the absence of a double-blind design, the presence of an active control group does not necessarily control for placebo effects; participants might expect different amounts of improvement for the treatment and control interventions. We conducted a large survey to explore whether people expect greater cognitive benefits from an aerobic exercise intervention compared to a control intervention. If participants expect greater improvement following aerobic exercise, then the benefits of such interventions might be due in part to a placebo effect. In general, expectations did not differ between aerobic and non-aerobic interventions. If anything, some of the results suggest the opposite (e.g., respondents expected the control, non-aerobic intervention to yield bigger memory gains). These results provide the first evidence that cognitive improvements following aerobic fitness training are not due to differential expectations.
authors.affiliation: Department of Psychology, Florida State University, Tallahassee, Florida, United States of America.
authors.forename: Cary R
authors.initials: CR
authors.lastname: Stothart
authors.affiliation: Psychology Department, University of Illinois at Urbana-Champaign, Champaign, Illinois, United States of America.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Simons
authors.affiliation: Department of Psychology, Florida State University, Tallahassee, Florida, United States of America.
authors.forename: Walter R
authors.initials: WR
authors.lastname: Boot
authors.affiliation: Psychology Department, University of Illinois at Urbana-Champaign, Champaign, Illinois, United States of America.
authors.forename: Arthur F
authors.initials: AF
authors.lastname: Kramer
mesh_terms: D000328:Adult; D059031:Anticipation, Psychological / Q000502:physiology; D003071:Cognition / Q000502:physiology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007361:Intelligence Tests; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D010809:Physical Fitness / Q000502:physiology* / Q000523:psychology; D015990:Placebo Effect; D057185:Sedentary Behavior; D016138:Walking / Q000502:physiology* / Q000523:psychology