Theory of Planned Behavior suggested that customer purchase intention is a psychological construct that is different from attitude (Honkanen et al., 2006). The purchase intention is formed by consumer’s attitude, perceived behavior control and subjective norms. theory of planned behavior is based on the assumptions that an individual’s behavior is influenced by the numbers of psychological factors which includes subjective norms, perceived behavior control, beliefs, willingness to perform a behavior and attitude beliefs (Ajzen, 1991; Schaller & Malhotra 2015). Ajzen (2002) defined attitude as individual’s reaction about a particular behavior, more positive leads towards high intentions to perform a task.
Perceived behavior control is defined as individual’s assumptions regarding how easily a task can be performed. Individual having means to perform and find a behavior easily are more likely sustain that behavior (Schaller & Malhotra 2015).
Subjective norms are expectations that emerge from the individual’s surroundings and perceived as social stress. The greater the stress to perform a particular behavior, individual would more likely associated with that behavior (Ajzen, 2002).
Engel, Blackwell, and Miniard (1995) proposed the consumer’s purchase decision making model which divide the decision-making process into five stages i.e. (1) problem identification, (2) information search, (3) alternative evaluation, (4) purchase decision and (5) postpurchase behavior
Furthermore, Engel, et al. (1995) divided the purchase intention into unplanned buying, partially planned buying and fully planned buying. Unplanned buying means that consumers make decisions to purchase a particular product or brand on the spot and it’s an impulse buying behavior. Partially planned buying means that consumers only decide a product and its specification to buy and the specification before purchase a product, and brands types will decide later. Whereas, fully planned buying means that consumers already decided which product and brand to purchase.