Cognitive dissonance theory as applied to consumer behavior posits that when making a large and expensive purchase, those who have only recently made a purchase are more likely to retain a positive attitude toward the brand in question than those who bought the same brand a longer period of time ago. One topic associated with this consumer behavioral concept that would make an effective paper is to study the hypothesis that those who have made recent purchases tend to seek out positive information that will reinforce support for the choice they made.
Consumer behavior of children and teens is a rich topic for study. One angle would be to investigate the extent of influence on younger members of the family in accordance with the type of parental exchange involved. For instance, the topic studies how much more influence authoritarian parents hold over children in comparison to less intrusive parents. Another aspect to uncover is whether children of essentially neglectful parents are influenced in their buying decision at all by mother and father.
Advertising is the most obvious manner of direction consumer behavior at the disposal of commercial entities. While it may seem as if advertising is a particularly homogeneous and inclusive exercise, the topic of an insightful research project could reveal how advertising for the exact same product may differ between ethnic groups. Recommended approaches to this topic would be to pick a handful of quite specific products and reveal how the differences between how they are advertised directly to white Americans, Hispanics, Asian and African-Americans.
The behavior of some consumer actions is predicated upon the field of semiotics which finds associations between objects, signs and symbols. Consumer choices are very often manipulated by barely conscious attachment to certain symbolic entities. A rich topic for studying semiotics as it relates to consumer behavior would lead you to address the overriding consumer connotations to brands as disparate as Mercedes-Benz, Campbell's Soup, Nokia and American Express. Pick just about any well known brand to determine its consumer oriented connotations and relate how this association between brand and consumer affects behavior.