Effects of neurofeedback training on performance in laboratory tasks: A systematic review.

Neurofeedback procedures are attracting increasing attention in the neuroscience community. Based on the principle that participants, through suitable feedback, may learn to affect specific aspects of their brain activity, neurofeedback interventions have been applied to basic research, translational, and clinical science. A large segment of the available empirical research as well as review articles have focused on the extent to which neurofeedback interventions affect mental health outcomes, cognitive capacity, aging, and other complex behaviors. Another segment has aimed to characterize the extent to which neurofeedback affects the targeted neural processes. At this time, there is no current systematic review of the effects of neurofeedback on healthy participants' performance in experimental tasks. Such a review is relevant in this rapidly evolving field because changes in experimental task performance are traditionally considered a hallmark of changing neurocognitive processes, often established in neurotypical individuals. This systematic review addresses this gap in the literature using the PRISMA method, building on earlier reviews on the same topic. Empirical studies using EEG or fMRI to alter brain processes linked to established cognitive and affective laboratory tasks were reviewed. Systematic quality assessment and z-curve analyses were also conducted. Substantial variability was found regarding the study designs used, the implementation of the feedback, and the neural targets of feedback. Importantly, only a minority of the studies reported statistically meaningful effects of neurofeedback on performance in cognitive and affective tasks. The z-curve analyses found no evidence for reporting bias or unsound research practices. Quality control and effect size analyses showed few systematic relations between study characteristics such as sample size or experimental control on the one hand and outcome on the other. Overall, the present study does not support strong effects of NFT on performance in laboratory tasks. Implications for future work are discussed.