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 isnt 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 users 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 users prior rating of the movie. In the second experiment, users rated movies they hadnt rated before. Some users saw "predictions" that were skewed higher or lower, while a control group saw only the systems 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 systems 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 systems 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.
Product placement: Only brands placed very prominently benefit from 3D technology
07.07.2016 | Alpen-Adria-Universität Klagenfurt
NASA Goddard network maintains communications from space to ground
02.03.2016 | NASA/Goddard Space Flight Center
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
27.10.2016 | Life Sciences
27.10.2016 | Life Sciences
27.10.2016 | Power and Electrical Engineering