Expectation effects in working memory training

Abstract

There is a growing body of research focused on developing and evaluating behavioral training paradigms meant to induce enhancements in cognitive function. It has recently been proposed that one mechanism through which such performance gains could be induced involves participants' expectations of improvement. However, no work to date has evaluated whether it is possible to cause changes in cognitive function in a long-term behavioral training study by manipulating expectations. In this study, positive or negative expectations about cognitive training were both explicitly and associatively induced before either a working memory training intervention or a control intervention. Consistent with previous work, a main effect of the training condition was found, with individuals trained on the working memory task showing larger gains in cognitive function than those trained on the control task. Interestingly, a main effect of expectation was also found, with individuals given positive expectations showing larger cognitive gains than those who were given negative expectations (regardless of training condition). No interaction effect between training and expectations was found. Exploratory analyses suggest that certain individual characteristics (e.g., personality, motivation) moderate the size of the expectation effect. These results highlight aspects of methodology that can inform future behavioral interventions and suggest that participant expectations could be capitalized on to maximize training outcomes.

Keywords: cognitive training; expectation effect; placebo effect; working memory training.

Fig. 1.

A flowchart of the study procedure and assignment to one of four experimental conditions.

Fig. 2.

Effects of training and expectation conditions on overall performance on the posttest and delayed-test cognitive batteries, controlling for pretest performance. Error bars represent SEM.

Fig. 3.

Significant moderator analyses for (A) extraversion and the expectation effect on n-back performance, (B) the BAS reward subscale and the expectation effect on n-back performance, (C) the BAS fun-seeking subscale and the expectation effect on task-switching performance, and (D) mindset and the expectation effect on RAPM performance. All moderation analyses controlled for respective pretest task performance.