Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Good ratings gone bad: study shows recommender systems can manipulate users’ opinions

04.04.2003


Study also reports users lose trust in systems that give phony ratings

Online "recommender systems" are used to suggest highly rated selections for book buyers, movie renters or other consumers, but a new study by University of Minnesota computer science researchers shows for the first time that a system that lies about ratings can manipulate users’ opinions. Over time, however, users lose trust in unscrupulous systems.

The Minnesota research group, led by professors Joseph Konstan and John Riedl, conducted experiments with MovieLens, a member driven movie recommendation Web site, which the Minnesota team created to put their research on recommender systems into practice. The results of their latest studies will be presented at the CHI 2003 Conference on Human Factors in Computing Systems, April 5-10, 2003, in Fort Lauderdale, Fla. The work is supported by the National Science Foundation, the independent federal agency that supports basic research in all fields of science and engineering.

The results suggest that "shills," who flood recommender systems with artificially high (or low) ratings, can have an impact and that recommender systems will take longer than previously expected to self-correct. The idea behind self-correction is that misled users will come back and give the item in question a more accurate rating.

"This study isn’t about defending against shill attacks, but about trust in the system," Konstan said. "Our results show that individual shilling will take longer to correct, but the larger impact is the loss of trust in the system." In the Minnesota study, users were sensitive to the quality of the predictions and expressed dissatisfaction when the system gave inaccurate ratings.

Taken together, the experiments provide several tips for the designers of interfaces to recommender systems. Interfaces should allow users to concentrate on rating while ignoring predictions. Finer-grained rating scales are preferred over simple "thumbs up, thumbs down" scales, but are not essential to good predictions. Finally, because users are sensitive to manipulation and inaccurate predictions, to keep customers happy, no recommender system at all is better than a bad recommender system.

Many online shopping sites use recommender systems to help consumers cope with information overload and steer consumers toward products that might interest them. Recommender systems based on "collaborative filtering" generate recommendations based on a user’s selections or ratings and the ratings of other users with similar tastes.

The CHI 2003 paper reports the results of three experiments that attempted to shed light on questions such as "Can the system make a user rate a ’bad’ movie ’good’?" "Do users notice when predictions are manipulated?" "Are users consistent in their ratings?" and "How do different rating scales affect users’ ratings?"

"To our knowledge, no one has studied how recommendations affect users’ opinions," Konstan said. "We thought it was a socially important question because many of these systems are used in commercial applications. We found that if the system lies you can gain some influence in the short term, but you lose trust in the long term. This is a lot like trust between humans."

In the first experiment, users re-rated movies while presented with some "predictions" that were different from the user’s prior rating of the movie. In the second experiment, users rated movies they hadn’t rated before. Some users saw "predictions" that were skewed higher or lower, while a control group saw only the system’s accurate predictions. The final experiment had users re-rate movies using three different rating scales and asked users their opinions of the different scales. In the re-rating experiment, users were generally consistent, but they did tend to change their rating in the direction of the system’s skewed "prediction." In fact, users could even be influenced to change a rating from negative to positive or vice versa. When users rated previously unrated movies, they tended to rate toward the system’s prediction, whether it was skewed or not.

Konstan also noted that, while this study used movie ratings, recommender systems have much wider application. Such systems can also be used for identifying highly rated research papers from a given field or for knowledge management in large enterprises. New employees, for example, can bring themselves up to speed by focusing on highly rated news items or background materials.

David Hart | National Science Foundation
Further information:
http://www.movielens.umn.edu/
http://www.nsf.gov

More articles from Communications Media:

nachricht Arguments, Emotions, and News distribution in social media - Leibniz-WissenschaftsCampus Tübingen
04.05.2018 | Leibniz-Institut für Wissensmedien

nachricht High Number of Science Enthusiasts in Switzerland
05.02.2018 | Universität Zürich

All articles from Communications Media >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Designer cells: artificial enzyme can activate a gene switch

22.05.2018 | Life Sciences

PR of MCC: Carbon removal from atmosphere unavoidable for 1.5 degree target

22.05.2018 | Earth Sciences

Achema 2018: New camera system monitors distillation and helps save energy

22.05.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>