vrml (3027321) writes Biofeedback is well-known as a relaxation technique, but the HCI Lab of the University of Udine has tried to use it for the opposite purpose: making people anxious. The technique, described by a paper in the November 2014 issue of the Interacting with Computers journal, exploits heartbeat detection. While users navigated a 3D world, the computer detected and played their actual heartbeat (users were not told it was theirs) in the audio background of the virtual world. At a couple of times during the experience, the application artificially increased the frequency of the played heartbeat and then reverted it to the actual one after some seconds. The study described in the paper contrasts the technique with aversive stimuli frequently used in video games when the character gets hurt such as decreasing health bars or increasing the frequency of an heartbeat sound that is not related to the user's actual heartbeat. The biofeedback-based technique produced much larger (subjective as well as physiological) levels of user anxiety than those classic aversive stimuli.