In the TPB, the most detailed substantive information about the determinants of a behaviour is contained in a person’s behavioural, normative and control beliefs. The
theory does not specify where these beliefs originated; it merely points to a host of possible background factors that may influence the beliefs people hold – factors of a personal nature such as personality and broad life values; demographic variables such as education, age, gender and income; and exposure to media and other sources of information. Factors of this kind are expected to influence intentions and behaviour indirectly by their effects on the theory’s more proximal determinants. Most empirical studies assess a few demographic characteristics if only considered as control variables. Some studies, however, focus on one or more background factors that, for intuitive or theoretical reasons, are considered to be relevant to the behaviour under investigation.