Phil 6.18.18

ASRC MKT 7:00 – 8:00

  • Nice ride on Saturday on Skyline drive
  • Using Social Network Information in Bayesian Truth Discovery
    • We investigate the problem of truth discovery based on opinions from multiple agents who may be unreliable or biased. We consider the case where agents’ reliabilities or biases are correlated if they belong to the same community, which defines a group of agents with similar opinions regarding a particular event. An agent can belong to different communities for different events, and these communities are unknown a priori. We incorporate knowledge of the agents’ social network in our truth discovery framework and develop Laplace variational inference methods to estimate agents’ reliabilities, communities, and the event states. We also develop a stochastic variational inference method to scale our model to large social networks. Simulations and experiments on real data suggest that when observations are sparse, our proposed methods perform better than several other inference methods, including majority voting, the popular Bayesian Classifier Combination (BCC) method, and the Community BCC method.
  • Scale-free correlations in starling flocks
    • From bird flocks to fish schools, animal groups often seem to react to environmental perturbations as if of one mind. Most studies in collective animal behavior have aimed to understand how a globally ordered state may emerge from simple behavioral rules. Less effort has been devoted to understanding the origin of collective response, namely the way the group as a whole reacts to its environment. Yet, in the presence of strong predatory pressure on the group, collective response may yield a significant adaptive advantage. Here we suggest that collective response in animal groups may be achieved through scale-free behavioral correlations. By reconstructing the 3D position and velocity of individual birds in large flocks of starlings, we measured to what extent the velocity fluctuations of different birds are correlated to each other. We found that the range of such spatial correlation does not have a constant value, but it scales with the linear size of the flock. This result indicates that behavioral correlations are scale free: The change in the behavioral state of one animal affects and is affected by that of all other animals in the group, no matter how large the group is. Scale-free correlations provide each animal with an effective perception range much larger than the direct inter-individual interaction range, thus enhancing global response to perturbations. Our results suggest that flocks behave as critical systems, poised to respond maximally to environmental perturbations.
  • Interaction ruling animal collective behavior depends on topological rather than metric distance: Evidence from a field study
    • By reconstructing the three-dimensional positions of individual birds in airborne flocks of a few thousand members, we show that the interaction does not depend on the metric distance, as most current models and theories assume, but rather on the topological distance. In fact, we discovered that each bird interacts on average with a fixed number of neighbors (six to seven), rather than with all neighbors within a fixed metric distance. We argue that a topological interaction is indispensable to maintain a flock’s cohesion against the large density changes caused by external perturbations, typically predation. …
  • Thread on the failure to replicate the Stanford Prison Experiment by Alex Haslam (scholar) (home page). Paper coming soon
    • The Stanford Prison Experience—as it is presented in textbooks—presents human nature as naturally conforming to oppressive systems. This is a lesson that extends well beyond prison systems and the field criminology—but it’s wrong. Alex and his colleagues (especially Steve Reicher) have been arguing for years that conformity often emerges when leaders cultivate a sense of shared identity. This is an active, engaged process—very different from automatic and mindless conformity.
  • Started Irrational Exuberance, by Robert Shiller
  • Send note to Don, Aaron and Shimei
  • Read Ego-motion in Self-Aware Deep Learning on Medium. It’s about reflective learning of navigation in physical spaces, though I wonder if there is an equivalent process in belief spaces. Looked through scholar and
  • Slide prep and Fika walkthrough
    • Went well. Ravi suggested adding another slide that discusses the methods in detail, while Sy pretty much demanded that I get rid of “Questions” and put the title of the paper in its place
    • When adding the detail for Ravi, I discovered that the simulator and map reconstruction did not handle single, high dimensional agents well, so I spent a few hours fixing bugs to get the screen captures to build the slides.

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