In marketing, there are two fundamental principles called Attitude to Behaviour (A to B) and Behaviour to Attitude (B to A) marketing.
In A to B marketing, you target and change the attitude of the consumer first, so that the change in the attitude may result in a desired change in the behaviour. For example, you tell the consumer the toothpaste whitens your teeth, so that this attitude may result in the change in behaviour of buying the product. This is what most ATL activities do.
In B to A marketing, you target and change the behaviour of the consumer first, so that the change in the behaviour may result in a desired change in the attitude. For example, the whitening toothpaste gives a promotion of 1+1 free that makes you buy the product. After using the product (behavioural change), you liked it (favourable attitude) and you changed your earlier inimical attitude towards the product. This is what most BTL activities do.