**2.2 Information sources and searching plan**

We apply three searching databases: IEEE Xplore, Scopus, and PubMed/MEDLINE. This review includes three strategies (see **Table 3**) with two additional plans for finding articles. The pre-searching plan is designed relatively broad so that a brief idea of the current gaming MI-BCI systems could help revise the main-researching plan. In contrast, the main-searching plan is designed relatively specifically after referring to


**Table 2.** *Summarization of eligibility criteria.* *Improving the Brain-Computer Interface Learning Process with Gamification in Motor Imagery:… DOI: http://dx.doi.org/10.5772/intechopen.105715*


#### **Table 3.**

*Three searching plans with separate groups.*

one current published topic-relevant SR [25] and the pre-searching result. We design a compensatory plan so that targeted articles with a slightly expressive difference are unlikely missed. One additional search plan utilizes Google scholar, and another technique is to dig topic-related articles presented as references in the articles already reviewed. The key searching terms are separated into three groups based on the MESH library in Pubmed, template SR [25], and another relevant SR discussing BCI games [27]. All search plans are based on title, abstract, and keywords (TAK), and duplicative articles would be identified and removed via EndNote X9 and a relatively deep read.
