Perceived behavioural control/self-efficacy. The TPB is an extension of the TRA incorporating the concept of perceived behavioural control (PBC) as an intervening variable predicting both intention and also actual behavioural change directly [38, 39] . The direct effect of PBC on actual behavioural change partly explains why not all intention translates into behaviour. Previous reviews suggested that intention-behaviour relationships could be moderated by perceived behavioral control, with higher levels of perceived behavioural control improving prediction of intention on behaviour [42, 43] . Although some researchers suggested that PBC differs from self-efficacy because selfefficacy emphasized perceived internal control more while PBC also considers external control factors [45] , a systemic review on the efficacy of TBP found that PBC and self-efficacy had comparable effects on intention and behaviour [41] . Despite being a dominant theory of behavioural change, because the TPB is limited in predicting behaviour we sought to enhance its predictive power by replacing PBC with self-efficacy and incorporating enhanced social effects to accommodate external control factors.