Description of the studies
Figure 2 illustrates the distribution of the studies included in this systematic review: the number of studies per country, the number of studies per year (studies conducted in Europe in dark grey, studies conducted in North America in light grey, studies conducted in South America in middle grey, and studies conducted in Asia in white), and the study methods (from white to black: 51.2% of studies used self-reported measures, 18.6% behavioral measures, 11.6% electrophysiological measures, 11.6% neuroimaging measures, and 7% physiological measures).