We searched the PubMed and PsycINFO databases for all combinations of the keyword _attention_ with _tDCS_, _tACS_, or _tRNS_ (abbreviated and written out fully). The search yielded 291 non-duplicate records. After screening the title and abstract of each, we excluded 177 records, because they: * had no English (1) full text available (1) * were not empirical studies (76), or were pilot/case studies (8) * did not apply any stimulation (22) or used TMS (14) * did not use a cognitive task (13) * did not study humans (4) or a population other than healthy participants or neglect patients (38) After inspecting the full text of the remaining 114 records, we excluded a another 74 studies, because they: * did not contain a measure of the effect of stimulation on task performance, in terms of either accuracy or reaction time (7) * provided insufficient methodological detail about the tDCS procedure (1) * seemed more closely related to another cognitive domain than attention, namely: * emotion (6) * motor (6) * language (4) * perception (4) * cognitive control (3) * decision making (3) * long-term memory (3) * numerical cognition (3) * response inhibition (2) * creativity (1) * intelligence (1) * pain (1) * reward (1) * social cognition (1) * did not have the explicit aim to enhance attention, but used attention tasks to assess: * whether the effects of stimulation were specific to the cognitive domain of interest (5) * transfer after training on other cognitive tasks (4) Forty studies passed the screening in total. Using these 40 records, we looked for more relevant studies by: * scanning their reference sections * checking for citations on Google Scholar This brought an additional 12 records to light, for a grand total of 52 included studies.