“…The sample sizes of the analysed studies were heterogenous and ranged from 12 to 360 participants. Among the 18 studies, six were conducted with pre-school children [7,18,19,21,23,25], four with primary school children [4,6,16,20], one with high school students [26] and seven with adult participants [10,14,36,41,55,57,67]. Therefore, learning contexts related to learning a second language (artificial languages were absent) were dominant in our study set.…”