hat styles do you like? ct just one Byrs. Theo Eye Bline. Ken. ROS ROCK Alternative Art Experimental Hard Rock。 Hardcore Pop/Top40 Figure 4: Genre Filtering in MediaUnbound they did not like being forced to name the single genre the if they can easily generate new sets of recommendations preferred, feeling that their tastes bridged several genres. ithout a lot of effort. Other users were unsure what exactly what kinds of music Design Suggestion: Users should not perceive the the genre represented since the systems categorization into recommendation set as dead end. This is important genres did not map to their mental models. MediaUnbound and Song Explorer, two of the music recommender systems, If they like the recommendations, then they might be faced such genre filtering problems(see Figure 4). erested in looking at more; if they dislike the Genre is a tricky thing in recommendations On the one hand recommendations, they might be interested in refining their recommender systems offer a way for users to move beyond atings in order to generate new recommendation set genre-based book/movie/music exploratin. On the otl hand, genres do work well as shorthand for a lot of likes and Information about Recommended Items dislikes of the user, and therefore help focus the The presence of longer descriptions of individual items recommendations. Over the course of the past year, we have correlates positively with both the perceived usefulness and bserved that nearly all the major recommender systems ease of use of the recommender system( Study 1). This have added a question about genre preferences indicates that users like to have more information about the Design Suggestion: Our design suggestion is to offer filter recommended item( book/movie description, author /actor like controls over genres, but to make them as simple and musician, plot summary, genre information, reviews by self-explanatory as possible. Users should be given the other users) choice of choosing more than one genre. Also a few lines of This finding was reinforced by the difference between the explanation of each genre should be provided. This will two versions of rating zone the first version of allow users to understand what kind of music /books/ Rating Zone's Quick Picks showed only the book title and movies the genre label represents. author name in the list of recommendations user evaluations were almost wholly negative as a result The second version 2)TAKING THINGS APAI UTPUT FROM THE of Rating Zone changed this situation very simply: by SYSTEM providing a link to item-specific information at Ease of Getting More Recommendations Amazon.com.Figure5showsthedifferenceinperceived stems vary in the number of sefulness between both versions of the same systems. recommendations they generate. Amazon suggests 15 items (Note: Error bars in figures 5-9 represent standard errors. in the initial set, while other sites show 10 items per screen, a different problem occurred at Movie Critic, where detailed for as many screens as the user wishes to view. Users appear information was offered but users had trouble finding it. to be sensitive to the number of recommendations. However, This was because the item information was located sey the sheer number is less impor rtant tha mouse clicks away and the site had poor navigation de generating additional sets of recommendations. Some We have noticed that users find several types of information key in making up their minds. We use music systems as an simply by rating additional items. Other systems, however, example to describe the type of information users found recommendations. Users perceive the system as easier to use Basic Item Information: This includes song, album, artists name, genre information, when album was released. Usersthey did not like being forced to name the single genre they preferred, feeling that their tastes bridged several genres. Other users were unsure what exactly what kinds of music the genre represented since the system’s categorization into genres did not map to their mental models. MediaUnbound and SongExplorer, two of the music recommender systems, faced such genre filtering problems (see Figure 4). Genre is a tricky thing in recommendations. On the one hand recommender systems offer a way for users to move beyond genre-based book / movie / music exploration. On the other hand, genres do work well as shorthand for a lot of likes and dislikes of the user, and therefore help focus the recommendations. Over the course of the past year, we have observed that nearly all the major recommender systems have added a question about genre preferences. Design Suggestion: Our design suggestion is to offer filter￾like controls over genres, but to make them as simple and self-explanatory as possible. Users should be given the choice of choosing more than one genre. Also a few lines of explanation of each genre should be provided. This will allow users to understand what kind of music / books / movies the genre label represents. 2) TAKING THINGS APART: OUTPUT FROM THE SYSTEM Ease of Getting More Recommendations Recommender systems vary in the number of recommendations they generate. Amazon suggests 15 items in the initial set, while other sites show 10 items per screen, for as many screens as the user wishes to view. Users appear to be sensitive to the number of recommendations. However, the sheer number is less important than the ease of generating additional sets of recommendations. Some systems permit users to modify their recommendations simply by rating additional items. Other systems, however, require the user to repeat the entire rating process to see new recommendations. Users perceive the system as easier to use if they can easily generate new sets of recommendations without a lot of effort. Design Suggestion: Users should not perceive the recommendation set as a dead end. This is important regardless of whether they like the recommendations or not. If they like the recommendations, then they might be interested in looking at more; if they dislike the recommendations, they might be interested in refining their ratings in order to generate new recommendation sets. Information about Recommended Items The presence of longer descriptions of individual items correlates positively with both the perceived usefulness and ease of use of the recommender system (Study 1). This indicates that users like to have more information about the recommended item (book / movie description, author / actor / musician, plot summary, genre information, reviews by other users). This finding was reinforced by the difference between the two versions of Rating Zone. The first version of RatingZone's Quick Picks showed only the book title and author name in the list of recommendations; user evaluations were almost wholly negative as a result. The second version of RatingZone changed this situation very simply: by providing a link to item-specific information at Amazon.com. Figure 5 shows the difference in perceived usefulness between both versions of the same systems. (Note: Error bars in figures 5 - 9 represent standard errors.) A different problem occurred at MovieCritic, where detailed information was offered but users had trouble finding it. This was because the item information was located several mouse clicks away and the site had poor navigation design. We have noticed that users find several types of information key in making up their minds. We use music systems as an example to describe the type of information users found useful. Basic Item Information: This includes song, album, artists name, genre information, when album was released. Users Figure 4: Genre Filtering in MediaUnbound