Hootle Plus : A Group Recommender System Supporting Preference Negotiation

This paper presents an approach to group recommender systems that focuses its attention on the group's social interaction during the formulation, discussion and negotiation of the features the item to be jointly selected should possess. The system supports a collaborative preference elicitation and negotiation process where desired item features can be defined individually, but group consensus is needed for them to become active in the item filtering process. Users can provide feedback on other members' preferences and change their significance, bringing up new recommendations each time individual settings are modified. The last stage in the decision process is also supported, when users collectively select the final item from the recommendation set. We developed the prototype hotel recommender Hootle+ and evaluated it in a user study involving groups of different size. The results indicate a good overall satisfaction, which increases with group size. However, the success ratio for bigger groups is lower than for small groups, raising questions for follow-up research.