Not Using the Car to See the Sidewalk: Quantifying and Controlling the Effects of Context in Classification and Segmentation

Importance of visual context in scene understanding tasks is well recognized in the computer vision community. However, to what extent the computer vision models for image classification and semantic segmentation are dependent on the context to make their predictions is unclear. A model overly relying on context will fail when encountering objects in context distributions different from training data and hence it is important to identify these dependencies before we can deploy the models in the real-world. We propose a method to quantify the sensitivity of black-box vision models to visual context by editing images to remove selected objects and measuring the response of the target models. We apply this methodology on two tasks, image classification and semantic segmentation, and discover undesirable dependency between objects and context, for example that "sidewalk" segmentation relies heavily on "cars" being present in the image. We propose an object removal based data augmentation solution to mitigate this dependency and increase the robustness of classification and segmentation models to contextual variations. Our experiments show that the proposed data augmentation helps these models improve the performance in out-of-context scenarios, while preserving the performance on regular data.Comment: 14 pages (12 figures

Remote booting in a hostile world: to whom am I speaking? [Computer security]

“This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder." “Copyright IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.”Today's networked computer systems are very vulnerable to attack: terminal software, like that used by the X Window System, is frequently passed across a network, and a trojan horse can easily be inserted while it is in transit. Many other software products, including operating systems, load parts of themselves from a server across a network. Although users may be confident that their workstation is physically secure, some part of the network to which they are attached almost certainly is not secure. Most proposals that recommend cryptographic means to protect remotely loaded software also eliminate the advantages of remote loading-for example, ease of reconfiguration, upgrade distribution, and maintenance. For this reason, they have largely been abandoned before finding their way into commercial products. The article shows that, contrary to intuition, it is no more difficult to protect a workstation that loads its software across an insecure network than to protect a stand-alone workstation. In contrast to prevailing practice, the authors make essential use of a collision-rich hash function to ensure that an exhaustive off-line search by the opponent will produce not one, but many candidate pass words. This strategy forces the opponent into an open, on-line guessing attack and offers the user a defensive strategy unavailable in the case of an off-line attack.Peer reviewe

Gameplay experience in a gaze interaction game

Assessing gameplay experience for gaze interaction games is a challenging task. For this study, a gaze interaction Half-Life 2 game modification was created that allowed eye tracking control. The mod was deployed during an experiment at Dreamhack 2007, where participants had to play with gaze navigation and afterwards rate their gameplay experience. The results show low tension and negative affects scores on the gameplay experience questionnaire as well as high positive challenge, immersion and flow ratings. The correlation between spatial presence and immersion for gaze interaction was high and yields further investigation. It is concluded that gameplay experience can be correctly assessed with the methodology presented in this paper.Comment: pages 49-54, The 5th Conference on Communication by Gaze Interaction - COGAIN 2009: Gaze Interaction For Those Who Want It Most, ISBN: 978-87-643-0475-

A comparative evaluation of algorithms for discovering translational patterns in Baroque keyboard works

We consider the problem of intra-opus pattern discovery, that is, the task of discovering patterns of a specified type within a piece of music. A music analyst undertook this task for works by Domenico Scarlattti and Johann Sebastian Bach, forming a benchmark of 'target' patterns. The performance of two existing algorithms and one of our own creation, called SIACT, is evaluated by comparison with this benchmark. SIACT out-performs the existing algorithms with regard to recall and, more often than not, precision. It is demonstrated that in all but the most carefully selected excerpts of music, the two existing algorithms can be affected by what is termed the 'problem of isolated membership'. Central to the relative success of SIACT is our intention that it should address this particular problem. The paper contrasts string-based and geometric approaches to pattern discovery, with an introduction to the latter. Suggestions for future work are given

The Effects of Displayed Violence and Game Speed in First-Person Shooters on Physiological Arousal and Aggressive Behavior

Many studies have been conducted to examine the effects of displayed violence in digital games on outcomes like aggressive behavior and physiological arousal. However, they often lack a proper manipulation of the relevant factors and control of confounding variables. In this study, the displayed violence and game speed of a recent first-person shooter game were varied systematically using the technique of modding, so that effects could be explained properly by the respective manipulations. Aggressive behavior was measured with the standardized version of the Competitive Reaction Time Task or CRTT (Ferguson et al., 2008}. Physiological arousal was operationalized with four measurements: galvanic skin response (GSR), heart rate (HR), body movement, force on mouse and keyboard. A total of N = 87 participants played in one of four game conditions (low- vs. high-violence, normal- vs. high speed) while physiological measurements were taken with finger clips, force sensors on input devices (mouse and keyboard), and a Nintendo Wii balance board on the chair they sat on. After play, their aggressive behavior was measured with the CRTT. The results of the study do not support the hypothesis that playing digital games increases aggressive behavior. There were no significant differences in GSR and HR, but with a higher game speed, participants showed less overall body movement, most likely to meet the game’s higher demands on cognitive and motor capacities. Also, higher game speed and displayed violence caused an increase in applied force on mouse and keyboard. Previous experience with digital games did not moderate any of these findings. Moreover, it provides further evidence that the CRTT should only be used in a standardized way as a measurement for aggression, if at all. Using all 7 different published (though not validated) ways to calculate levels of aggression from the raw data, “evidence” was found that playing a violent digital game increases, decreases, or does not change aggression at all. Thus, the present study does extend previous research. Firstly, it shows the methodological advantages of modding in digital game research to accomplish the principles of psychological (laboratory) experiments by manipulating relevant variables and controlling all others. It also demonstrates the test-theoretical problems of the highly diverse use of the CRTT. It provides evidence that for a meaningful interpretation of effects of displayed violence in digital games, there are other game characteristics that should be controlled for since they might have an effect on relevant outcome variables. Further research needs to identify more of those game features, and it should also improve the understanding of the different measures for physiological arousal and their interrelatedness