There are various factors contributing to attitude change. The factors can be cognitive conative or affective. other factors like perceived behavioural control also contribute to it.
There are many factors which contribute to attitude distortion.The psychological orientation of the consumer also affect the attitude towards the products and servivces.
Attitude is most commonly defined as a Behavioural Tendency. Thus if there is a difference between attitudes, (measured obtrusively), and Behaviour, (measured unobtrusively), then it only confirms that the obtrusive measurement of attitudes is not externally valid.
Attitudes are most validly measured be observing behaviour (unobtrusively) and then inferring from the behaviours, what the attitudes must have been to produce such behaviours.