The concept of "frame of reference" offers a perspective from which to examine the many factors which affect advertising response. The advertiser is interested in affecting two types of overt behavior. First, the individual is induced to select a particular stimulus (the advertisement) from competing stimuli (such as other people, noise, and other ads). The advertiser must attract attention away from such competition while delivering the message clearly. Secondly, the advertiser seeks to affect the behavior intended by the ad (writing your congressman, picking up a pack of gum). The advertisement is no longer present in the external field, but its message is remembered and considered relevant enough to lead to the intended form of action. (JF)