10,095 research outputs found
Minimizing Bias in Estimation of Mutual Information from Data Streams
Mutual information is a measure for both linear and non-linear associations between variables. There exist several estimators of mutual information for static data. In the dynamic case, one needs to apply these estimators to samples of points from data streams. The sampling should be such that more detailed information on the recent past is available. We formulate a list of natural requirements an estimator of mutual information on data streams should fulfill, and we propose two approaches which do meet all of them. Finally, we compare our algorithms to an existing method both theoretically and experimentally. Our findings include that our approaches are faster and have lower bias and better memory complexity
Taking Synchrony Seriously: A Perceptual-Level Model of Infant Synchrony Detection
Synchrony detection between different sensory and/or motor channels appears critically important for young infant learning and cognitive development. For example, empirical studies demonstrate that audio-visual synchrony aids in language acquisition. In this paper we compare these infant studies with a model of synchrony detection based on the Hershey and Movellan (2000) algorithm augmented with methods for quantitative synchrony estimation. Four infant-model comparisons are presented, using audio-visual stimuli of increasing complexity. While infants and the model showed learning or discrimination with each type of stimuli used, the model was most successful with stimuli comprised of one audio and one visual source, and also with two audio sources and a dynamic-face visual motion source. More difficult for the model were stimuli conditions with two motion sources, and more abstract visual dynamics—an oscilloscope instead of a face. Future research should model the developmental pathway of synchrony detection. Normal audio-visual synchrony detection in infants may be experience-dependent (e.g., Bergeson, et al., 2004)
Daily Stress Recognition from Mobile Phone Data, Weather Conditions and Individual Traits
Research has proven that stress reduces quality of life and causes many
diseases. For this reason, several researchers devised stress detection systems
based on physiological parameters. However, these systems require that
obtrusive sensors are continuously carried by the user. In our paper, we
propose an alternative approach providing evidence that daily stress can be
reliably recognized based on behavioral metrics, derived from the user's mobile
phone activity and from additional indicators, such as the weather conditions
(data pertaining to transitory properties of the environment) and the
personality traits (data concerning permanent dispositions of individuals). Our
multifactorial statistical model, which is person-independent, obtains the
accuracy score of 72.28% for a 2-class daily stress recognition problem. The
model is efficient to implement for most of multimedia applications due to
highly reduced low-dimensional feature space (32d). Moreover, we identify and
discuss the indicators which have strong predictive power.Comment: ACM Multimedia 2014, November 3-7, 2014, Orlando, Florida, US
Predicting Human Interaction via Relative Attention Model
Predicting human interaction is challenging as the on-going activity has to
be inferred based on a partially observed video. Essentially, a good algorithm
should effectively model the mutual influence between the two interacting
subjects. Also, only a small region in the scene is discriminative for
identifying the on-going interaction. In this work, we propose a relative
attention model to explicitly address these difficulties. Built on a
tri-coupled deep recurrent structure representing both interacting subjects and
global interaction status, the proposed network collects spatio-temporal
information from each subject, rectified with global interaction information,
yielding effective interaction representation. Moreover, the proposed network
also unifies an attention module to assign higher importance to the regions
which are relevant to the on-going action. Extensive experiments have been
conducted on two public datasets, and the results demonstrate that the proposed
relative attention network successfully predicts informative regions between
interacting subjects, which in turn yields superior human interaction
prediction accuracy.Comment: To appear in IJCAI 201
Action-space clustering of tidal streams to infer the Galactic potential
We present a new method for constraining the Milky Way halo gravitational
potential by simultaneously fitting multiple tidal streams. This method
requires full three-dimensional positions and velocities for all stars to be
fit, but does not require identification of any specific stream or
determination of stream membership for any star. We exploit the principle that
the action distribution of stream stars is most clustered when the potential
used to calculate the actions is closest to the true potential. Clustering is
quantified with the Kullback-Leibler Divergence (KLD), which also provides
conditional uncertainties for our parameter estimates. We show, for toy
Gaia-like data in a spherical isochrone potential, that maximizing the KLD of
the action distribution relative to a smoother distribution recovers the true
values of the potential parameters. The precision depends on the observational
errors and the number of streams in the sample; using KIII giants as tracers,
we measure the enclosed mass at the average radius of the sample stars accurate
to 3% and precise to 20-40%. Recovery of the scale radius is precise to 25%,
and is biased 50% high by the small galactocentric distance range of stars in
our mock sample (1-25 kpc, or about three scale radii, with mean 6.5 kpc).
About 15 streams, with at least 100 stars per stream, are needed to obtain
upper and lower bounds on the enclosed mass and scale radius when observational
errors are taken into account; 20-25 streams are required to stabilize the size
of the confidence interval. If radial velocities are provided for stars out to
100 kpc (10 scale radii), all parameters can be determined with 10% accuracy
and 20% precision (1.3% accuracy in the case of the enclosed mass), underlining
the need for ground-based spectroscopic follow-up to complete the radial
velocity catalog for faint halo stars observed by Gaia.Comment: Accepted versio
- …