Transcranial brain stimulation (TBS) techniques are increasingly being adopted as tools in cognitive science and investigated as to their potential efficacy in neurological and psychiatric rehabilitation. The most popular TBS techniques include transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS) and transcranial random noise stimulation (tRNS). Though the proposed mechanisms of action differ between these techniques, broadly they allow for the modulation of neural activity and subsequent measurement of any resulting physiological and/or behavioural changes. However, whilst concrete theoretical and clinical advances have been achieved through research employing NIBS (most notably using TMS, but also tDCS/tACS/tRNS), doubts have recently been raised about the methodologies commonly employed in the field as well as the robustness and replicability of many of the reported effects. These doubts are emblematic of those that have also been highlighted recently in the wider fields of cognitive neuroscience and psychology research, fueled by non-optimal research practices, including small sample sizes or the tendency for positive results to be more readily submitted and/or published than null results (publication bias).



The aim of this Frontiers Research Topic is to highlight the value of negative findings for the TBS community, e.g., to guide the choice of stimulation parameters (by means of avoiding unsuccessful designs) and to work towards a more realistic picture of the robustness and reproducibility of TBS effects (by gauging the number of successful relative to unsuccessful attempts). Motivated by many reports of unpublished null results accumulating in file drawers (personal communications, own research), we welcome the submission of high quality studies involving the application of any TBS technique (focusing on either behavioural or neural outcome measures, or both), regardless of statistical significance of the outcome (‘negative’ or ‘positive’ findings), provided studies were appropriately designed and supported by a strong rationale. In particular, we welcome submissions of studies in the domain of cognition, e.g., on perception, attention, language, memory, etc., or those looking at resting state electrophysiological (e.g., EEG) measures in healthy participants.



We hope to bring together (1) novel research papers reporting negative (or positive) findings, as long as they are beyond the pilot stage, but also (2) failed (or successful) direct or conceptual replication studies, even when replication was not the primary scope. Finally, we (3) welcome meta-analyses or reviews that are in line with the aim of the Topic. With submission of research papers, we encourage formal sample and effect size calculation (prior or post data collection), willingness to make the acquired data publicly available (for instance on platforms such as the Open Science Framework; https://osf.io), as well as a clear indication when the data was recorded (for a snapshot on the current file drawer effect in the field).



We believe sharing failed attempts will have a positive impact on future experimental planning and will speed up knowledge acquisition of TBS techniques.

Keywords: transcranial electrical stimulation, transcranial magnetic stimulation, cognition, negative findings, reproducibility

Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.