Examining the contributions of placebo effects in cognitive training

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Project Summary/Abstract This project addresses fundamental controversies regarding the extent to which benefits of cognitive training may reflect, at least in part, placebo effects. Cognitive training is increasingly studied and applied as a potential approach to enhance cognitive capabilities in healthy young-to-middle-age adults as well to ameliorate and/or prevent age-related cognitive decline in individuals that may be at risk for developing ADRD. While extant data suggest that well-designed cognitive training paradigms can produce positive real-world change in cognitive functions, some researchers have suggested that the positive effects attributed to cognitive training may, in fact, reflect placebo effects. This criticism stems from the fact that, in even the best designed cognitive training studies, participants cannot be truly blinded to condition. While many cognitive training studies attempt to blind participants to the intent or purpose of the training (e.g., using an inert control training that participants might find plausible as an active intervention), because such control training experiences necessarily differ in key ways from the active training experiences, it has nevertheless been suggested that participants in cognitive training studies are able to intuit their condition and associated expectations and then show outcomes that are rooted purely in these expectations. Despite this suggestion appearing frequently in commentaries over the past several years, there exists little empirical work that directly addresses whether placebo effects may be at play in cognitive training and whether such effects can be of a magnitude that explains previous results in the field. Here we propose to overcome this fundamental gap in the field with a large-scale research study designed to explicitly examine placebo effects in cognitive training. In particular, taking lessons from outside domains that have more rigorously examined the induction of placebo effects, we utilize both “pure expectation” methods (i.e., verbally telling participants that an inert training protocol will enhance their cognitive functions) and “associative learning” methods (i.e., pairing training with subjectively experienced improved performance) in the attempt to purposefully drive maximal amplitude placebo effects. This will not only serve to resolve the proximal controversy regarding whether placebo effects in the domain, but if such effects are found, it will serve as a benchmark for future research (e.g., to potentially harness such effects). We will examine how the size of such effects may differ across age groups (younger and older adults), across cognitive domains (e.g., fluid intelligence, working memory, selective attention), and across testing contexts (in-lab versus remote). Finally, as outside domains have shown that there can be individual differences in the extent of placebo-responsiveness, we will also examine a set of individual difference variables (e.g., personality) as possible moderators for these differences. This research will provide a unique and foundational dataset that addresses directly and in a rigorous manner the extent to which cognitive training effects can be explained by, and/or augmented by, placebos, and inform future interventions addressing ADRD.