“…Researchers have referred to mental energy as attention ability (e.g., Kennedy et al, 2007; Snitz et al, 2009; Mohajeri et al, 2015), reaction time (Mohajeri et al, 2015), memory (e.g., Kennedy et al, 2004, 2007), language (e.g., Snitz et al, 2009), visual processing speed (e.g., Reay et al, 2006; Kennedy et al, 2007), executive function (Snitz et al, 2009), or emotional experiences (e.g., Johnson et al, 2008; Quartiroli et al, 2018). Further, with no definitive definition of mental energy, researchers have used all sort of measures such as depression and anxiety scales (e.g., Rogers et al, 2008), memory tests (Kennedy et al, 2004), attention tests (Kennedy et al, 2004), mood scales (e.g., Johnson et al, 2008; Quartiroli et al, 2018), visual analog scales (Kennedy et al, 2004; Kuan et al, 2017), or self-developed questionnaires (e.g., Dammann et al, 2013; Kueh et al, 2018) to assess what they called “mental energy.”…”