PARC technical publications

ThroughputScheduler: learning to schedule on heterogeneous Hadoop clusters

Christian Fritz, Bob Price, Roger Hoover and Johan de Kleer — Thu, 27 Jun 2013 00:00:00 -0700

Hadoop clusters are the technology of choice for big data analytics. The performance of these clusters is critical. Presently available schedulers for Hadoop clusters assign tasks to nodes without regard to the capability of the nodes. We propose a new scheduler, we call the Throughput Scheduler, which reduces overall job completion time on a heterogeneous cluster by actively assigning tasks to server nodes based on server capabilities and job task requirements. Server capabilities are learned by running probes jobs on the cluster. A Bayesian rule based efficient active learning scheme is derived to learn the resource requirements of Hadoop tasks online. An empirical evaluation on a simple problem demonstrates that the Throughput Scheduler can reduce total job completion time by almost 20% over the Hadoop Fair scheduler and 40% over the Hadoop FIFO scheduler. Throughput scheduler also reduces average mapping time by 33% compared to both existing schedulers.

Compact wavelength monitor for remote sensing applications suitable to precisely measure the wavelength of individual laser pulses

Peter Kiesel, Joerg Martini and Noble Johnson — Mon, 29 Apr 2013 00:00:00 -0700

Remote sensing of chemicals in a cloud can be accomplished, for example, with a tunable LIDAR system. The principle is to direct a series of laser pulses with different wavelengths at the cloud and measure the response (amount of reflected, scattered, or transmitted light) for each wavelength. The observed features in the recorded spectra reveal information on the constituents in the cloud. The most informative spectral bands for chemical identification are the wavelengths near 3 and 10um where gas molecules have characteristic vibrational modes that contribute characteristic structure in the spectra. For chemical identification it is essential to have precise wavelength information for each individual laser pulse.

We will describe a compact and fast wavelength monitor that can determine the wavelength of individual laser pulses with a resolution of a few pm. It combines a position sensor with a linear-variable-filter optical coating that converts the wavelength information of the incident light into a spatial intensity distribution on the photo-detector. Differential read-out of the position detector is used to determine the centroid of this distribution. Wavelength change between individual laser pulses is detected as a shift of the centroid of the spatial light distribution on the detector. We tested our wavelength monitor with a wavelength-tunable fiber laser which can produce randomly accessible sequences of laser pulses. The laser emits 100ns long laser pulses at 2kHz with selectable, well-defined wavelengths in the spectral range from 1030 to 1075nm. Such lasers can be used in combination with an OPO to convert the wavelength sequences in the 3um band for remote sensing. Our wavelength detector can measure the wavelength of each individual laser pulse with a resolution better than 10pm over the entire wavelength range.

Echoes from the past: how technology mediated reflection improves well-being

Ellen Isaacs and Alan Walendowski — Sat, 27 Apr 2013 00:00:00 -0700

As people document more of their lives online, some recent systems are encouraging people to later revisit those recordings, a practice we’re calling technology-mediated reflection (TMR). Since we know that unmediated reflection benefits psychological well-being, we explored whether and how TMR affects well-being. We built Echo, a smartphone application for recording everyday experiences and reflecting on them later. We conducted three system deployments with 44 users who generated over 12,000 recordings and reflections. We found that TMR improves well-being as assessed by four psychological metrics. By analyzing the content of these entries we discovered two mechanisms that explain this improvement. We also report benefits of very long-term TMR.

SENSOR project overview video

Ajay Raghavan, Ross Bringans, Noble Johnson, Peter Kiesel and Bhaskar Saha — Wed, 17 Apr 2013 00:00:00 -0700

Discussion of the challenges facing current battery management systems, and PARC's cost-effective solution, SENSOR (Smart Embedded Network of Sensors with Optical Readout), which allows real-time measurement of a battery’s internal state and conditions using embedded multiplexed fiber optic sensors and a highly sensitive compact readout unit combined with intelligent algorithms.

download information sheet in English | Japanese

Bootstrapping trust in online dating: social verification of online dating profiles

Emiliano De Cristofaro and Victoria Bellotti — Mon, 01 Apr 2013 00:00:00 -0700

This paper presents the results of a qualitative study on online dating practices. We conducted a series of semi-structured interviews and discovered that users are significantly concerned with the veracity of online dating profiles. Next, we present a user-centered design of an interface prototype -- called Certifeye -- that aims to bootstrap trust in online dating profiles by leveraging existing social network data. Users can certify their age, relationship status, and photos, by letting Certifeye verify that reported information corresponds to that displayed on the user's Facebook profile. Finally, we conducted a Mechanical Turk study to assess whether our veracity-enhancing interface successfully reduces users' concerns and found a statistically significant increase in trust by virtue of the Certifeye interface.

Vacuum steered-electron electric-field sensor

Dirk De Bruyker and Scott Limb — Mon, 11 Mar 2013 00:00:00 -0700

In a new type of MEMS electric-field sensor, a sheet of electrons is thermionically emitted by a hot cathode, flows through a vacuum, and is collected by a pair of anodes 2000 um away. As the electrons move through the vacuum, they are steered by external electric fields, resulting in a differential current at the anodes. The micromachined tungsten cathode has a low-work-function coating and is suspended over a cavity on a glass chip. These sensors have been operated both in a vacuum chamber and sealed in glass vacuum tubes. Measured sensitivities in a vacuum tube are 470 mV/m•Hz1/2 at 10 Hz, 230 mV/m•Hz1/2 at 100 Hz, and 140 mV/m•Hz1/2 at 1 kHz; sensitivities in a vacuum chamber at the same frequencies are 34, 6.3, and 2.4 mV/m•Hz1/2, respectively.

Persistent photoconductivity effects in printed n-channel organic transistors

Tse Nga (Tina) Ng, Bob Street and Janos Veres — Tue, 05 Mar 2013 00:00:00 -0800

Persistent photoconductivity of top-gate n-type organic transistors is investigated, as the irradiation of light leads to a negative shift in transistor threshold voltage and an increase in subthreshold current. These light-induced effects are enhanced when the gate is negatively biased during the light irradiation, and the recovery process is faster at 60°C than at 25°C. After storage in dark, full recovery is obtained for a transistor printed with a neat semiconductor, whereas for the device printed with a solution of the same semiconductor mixed with an insulator, only partial recovery is observed after four days. Other stress conditions (irradiation with a positive gate bias, irradiation without bias, and bias under dark) do not change the threshold voltage or the subthreshold current significantly. We attribute this photo phenomenon to the holes trapped and released at the dielectric/semiconductor interface and a smaller number of positive fixed charges generated in the bulk of the semiconductor layer.

The power of observation

David Cummins and Ellen Isaacs — Wed, 27 Feb 2013 00:00:00 -0800

Breakthroughs are often born in the lab or boardroom, but they live or die in the real world where people determine their value through real use. Xerox has employed ethnography for many years to gain a better understanding of human behavior in naturalistic settings, and now we are applying it to parking and parking enforcement. Our field research plays a critical role in rolling out new services and solutions, as it reveals unforeseen human variables that do not surface in the lab, in computer simulations, or in surveys and focus groups.

Studies of hole transport in Mg-doped AlGaN layers for deep-ultraviolet light emitters

Thu, 07 Feb 2013 00:00:00 -0800

AlGaN epilayers with Al composition higher than 50% are required for the realization of high-performance nitride-based light-emitting devices operating in the deep ultraviolet (DUV) region (λ < 300 nm), with their wide bandgap, UV transparency, and high optical confinement effect. In DUV light emitters, the growth of p-type AlGaN layers have been a major challenge because of the dramatic increase of Mg-acceptor thermal activation energy in AlGaN with increasing Al composition. Mg-doped AlGaN superlattice structures that utilize polarization fields to reduce Mg acceptor energy level have been reported as an alternative method to improve p-type doping efficiency of AlGaN layers. However, the existence of a large energy barrier in these structures severely degrades hole mobility and layer conductivity in the vertical direction, which makes these structures less useful in actual device structures. We have explored a number of designs for the p-layer for DUV light emitters and will report the results. The studies were conducted with p-layers of AlGaN grown on bulk AlN substrates. Van der Pauw devices were fabricated for variable-temperature Hall-effect measurements. The AlGaN p-layers show very small effective dopant activation energies in the range of 20 meV. This is to be compared to that for p-type GaN (146 meV) or AlGaN (323 meV). The results indicate that the acceptors in our AlGaN structure are activated via an athermal process. AlGaN p-n junction devices were grown on bulk AlN to confirm high vertical conductivity of the p-layer structure. Current-voltage and four-wire measurements on the p-n junction devices revealed that our p-layer provides higher conductivity, smaller voltage drop, and higher current drive compared to standard homogeneous AlGaN p-layer with similar average Al composition. A UV test diode employing our p-layer displayed DC-mode current injection level of 550 mA, which is equivalent to 11 kA/cm2.

Algorithm design for automated transportation camera image and video quality check modules

Ajay Raghavan and Bhaskar Saha — Sun, 03 Feb 2013 00:00:00 -0800

Photo enforcement devices for traffic rules such as red lights, stops, and speed are increasingly being deployed in cities around the world to ensure smooth traffic flow and public safety. These are typically unattended fielded systems, and so it is important to periodically check them for potential image/video quality problems that might interfere with their intended functionality. There is interest in automating such checks to reduce the operational overhead and human error involved in manually checking large camera device fleets. Examples of problems affecting such camera devices include exposure issues, focus drifts, obstructions, misalignment, download errors, and motion blur. Furthermore, in some cases, in addition to the sub-algorithms for individual problems, one also has to carefully design the overall algorithm and logic to check for and accurately classifying these individual problems. Examples include camera misalignment that can cause some scene elements to go out of focus for wide-area scenes or download errors that can be misinterpreted as an obstruction. Therefore, the sequence in which the sub-algorithms are utilized is also important. This paper presents an overview of these problems along with image and video quality solutions to detect and classify such faults.

Microspring characterization and flip chip assembly reliability

Fri, 01 Feb 2013 00:00:00 -0800

Electronics packaging based on stress-engineered spring interconnects has the potential to enable integrated IC testing, fine-pitch, and compliance not readily available with other technologies. We describe new spring contacts which simultaneously achieve low resistance (30 micron) in dense two-dimensional arrays (180 x 180 micron pitch). Mechanical characterization show individual springs operate at ~0.01 gm force. Electrical measurements and simulations imply the interface contact resistance contribution to a single contact resistance is < 40 mohms. Daisy chain test die consisting of 2844 contacts are assembled into flip chip packages with 100% yield. Thermocycle and humidity testing suggest packages with or without underfill can have stable resistance values and no glitches through over 1000 thermocycles or 7000 hrs of humidity. This work suggests that integrated testing and packaging can be performed with the springs, enabling new capabilities for markets such as multi-chip modules.

Participatory privacy: enabling privacy in participatory sensing

Emiliano De Cristofaro — Thu, 31 Jan 2013 00:00:00 -0800

Participatory Sensing is an emerging computing paradigm that enables the distributed collection of data by self-selected participants. It allows the increasing number of mobile phone users to share local knowledge acquired by their sensor-equipped devices, e.g., to monitor temperature, pollution level or consumer pricing information. While research initiatives and prototypes proliferate, their real-world impact is often bounded to comprehensive user participation. If users have no incentive, or feel that their privacy might be endangered, it is likely that they will not participate. In this article, we focus on privacy protection in Participatory Sensing and introduce a suitable privacy-enhanced infrastructure. First, we provide a set of definitions of privacy requirements for both data producers (i.e., users providing sensed information) and consumers (i.e., applications accessing the data). Then, we propose an efficient solution designed for mobile phone users, which incurs very low overhead. Finally, we discuss a number of open problems and possible research directions.

Kinetics of light induced defect creation in organic solar cells

Bob Street — Wed, 30 Jan 2013 00:00:00 -0800

The kinetics of light-induced recombination centers are measured in bulk heterojunction organic solar cells, as a function of exposure time, intensity and the illumination photon energy. The density of recombination centers increases with exposure time but stabilizes due to self-annealing. UV exposure is roughly ten times as effective for defect creation as white light or yellow-filtered white light for the same exposure intensity. The recombination centers that are created by light are indistinguishable from those created by x-ray irradiation for which the evidence indicates that the breaking of C-H bonds to create H-related localized states is the underlying mechanism.

Creating the future of printed electronics

Tue, 29 Jan 2013 00:00:00 -0800

Printed electronics are at a pivotal moment. There are not only tremendous opportunities for innovation and growth in new verticals and industries, but also the chance to define how we bring printed electronics into a new era of infrastructures through cooperation and partnerships. PARC, a Xerox company, has actively built a unique library of PE devices and processes to apply innovation in products, engaging with all the players from material makers to application companies. Janos Veres of PARC will discuss the immediate and immense opportunity to “set the rules” for the future of printed electronics, including design, manufacturing processes, and applications already available at PARC. Through the lens of the future of manufacturing infrastructure spearheaded by PARC, he will explore how printed electronics are now part of the larger and growing trend of how we “make” things differently. He will also detail the steps already taken and that need to be made in order to make this a reality.

From lab-scale ink-jet to mass-printed circuits

Gregory Whiting, Tse Nga (Tina) Ng, Bing Hsieh, Brent Krusor and Janos Veres — Tue, 29 Jan 2013 00:00:00 -0800

As more complex printed circuits and systems are being demonstrated it enables printed electronics to address an ever broadening application space. In order to access these developments for commercial products, current lab-scale printed devices must be scaled up to large-scale printing for mass production, which has an impact on both device design as well as materials choice. This presentation will describe the design rules currently used for lab-scale, ink-jet printed multi-layer complimentary circuits and their impact on device performance and variability. In addition an example of translating these designs to production scale equipment will be given, through PARC's partnership with the Sonoco Institute at Clemson University.

Design of printed transistor circuits for printed sensors

Tue, 29 Jan 2013 00:00:00 -0800

As printed transistor and sensor technologies advance, their integration into complex electronic systems becomes possible. Electronic design of such systems requires a systematic approach to simulation and design that takes into account the distinct challenges and opportunities presented by printed devices. In this talk, the speaker will discuss PARC’s approach to circuit design and modeling in the context of building sensor systems in partnership with Thinfilm Electronics based on an ink-jet printed organic TFT process.

2013 SIGCHI Awards - CHI Academy

Victoria Bellotti — Mon, 28 Jan 2013 00:00:00 -0800

Capturing mobile telepresence through logging and video shadowing: a two-phase study design

Ellen Isaacs and Peggy Szymanski — Mon, 21 Jan 2013 00:00:00 -0800

We used a two-phase study design that incorporated a novel video shadowing approach to learn how close-knit groups use technology to stay connected while mobile and to identify their unmet needs. In the first phase, we conducted a logging study with small groups in which each member logged all their interactions over 3 days, enabling us to identify suitable groups for the second, video shadowing phase. In the second phase, we separately observed and video recorded each member of the selected groups over the same half-day period as they connected in both mobile and stationary settings, a novel approach that others have been reluctant to try. This targeted shadowing approach enabled us to gain a rich understanding of the groups’ interactions across multiple media and devices that would not be possible using other indirect methods.

Comparison of static and dynamic printed organic shift registers

David Eric Schwartz and Tse Nga (Tina) Ng — Fri, 11 Jan 2013 00:00:00 -0800

Dynamic and static shift register circuits are fabricated with an inkjet process for printing complementary organic semiconductors. The static design is based on edge-triggered master-slave flip-flops and the dynamic design is based on a true-single-phase-clock architecture. The merits and drawbacks of the two approaches are considered and compared.

Origin of the tunable open circuit voltage in ternary blend bulk heterojunction organic solar cells

Bob Street and Dan Davies — Thu, 03 Jan 2013 00:00:00 -0800

Ternary blend bulk heterojunction organic solar cells comprising two polythiophene polymer donors or two fullerene acceptors are shown to have unique electronic properties. Measurements of the photocurrent spectral response and the open circuit voltage show that the HOMO and LUMO levels change continuously with composition. However, optical absorption of the exciton states retains the individual molecular properties of the two materials across the blend composition. This difference is attributed to the highly localized nature of the exciton which is contained within a molecule, and the more delocalized nature of electrons and holes that extend over several molecules and hence reflect the average composition. Even at low alloy concentration, optical excitation of the low energy polymer creates mobile electrons and holes with high efficiency, showing that excitons reach the interface even in systems below the percolation threshold. The combination of molecular excitations that can harvest a wide range of photon energies, and electronic states that can adjust the open circuit voltage are highly advantageous for efficient solar cells.

Highly sensitive tactile sensors integrated with organic transistors

Tse Nga (Tina) Ng — Tue, 01 Jan 2013 00:00:00 -0800

A capacitive pressure sensor with a nano-needle dielectric was successfully fabricated by a facile breath figures method and demonstrated a record sensitivity among polymer tactile sensors. The choice of dielectric microstructure is important, and the dielectric with a nano-needle showed sensitivity up to 1.76 kPa-1. This high sensitivity is due to the sharpness of nano-needles with radius of curvature around 10 nm. The capacitor with the nano-needle filler was integrated with an inkjet printed OTFT, and it showed high pressure response in agreement with capacitance change. This showed that the current of OTFTs increased with pressure due to an increase in capacitance, which in turn enhanced charge accumulation in the conduction channel. Structural advantage of the nano-needle film facilitated very high sensitivity for the capacitive pressure sensors. These pressure sensors integrated with printable OTFTs will be enabling for many flexible, large-area pressure sensing applications.

Flow cytometry on a chip

Peter Kiesel, Joerg Martini, Michael Recht, Marshall Bern and Noble Johnson — Tue, 01 Jan 2013 00:00:00 -0800

No commercial flow cytometer instrument meets all technical requirements for point-of-care detection in resource-limited settings; in particular the cost target remains extremely challenging. There are many interesting concepts under development especially for microfluidic-based flow cytometer. After a brief review of some new technologies important for on the flow anayte characterization we will describe an optical detection technique termed “spatially modulated fluorescence emission” developed at PARC which can delivers high signal-to-noise discrimination without precision optics to enable a flow cytometer that can combine high performance, robustness, compactness, low cost, and ease of use.

Fast and private computation of cardinality of set intersection and union

Emiliano De Cristofaro — Wed, 12 Dec 2012 00:00:00 -0800

In many everyday scenarios, sensitive information must be shared between parties without complete mutual trust. Private set operations are particularly useful to enable sharing information with privacy, as they allow two or more parties to jointly compute operations on their sets (e.g., intersection, union, etc.), such that only the minimum required amount of information is disclosed. In the last few years, the research community has proposed a number of secure and efficient techniques for Private Set Intersection (PSI), however, somewhat less explored is the problem of computing the magnitude, rather than the contents, of the intersection – we denote this problem as Private Set Intersection Cardinality (PSI-CA). This paper explores a few PSI-CA variations and constructs several protocols that are more efficient than the state-of-the-art.

Uncovering new ways people use technology to connect

Fri, 07 Dec 2012 00:00:00 -0800

Two-dimensional deformation potential model of mobility in small molecule organic semiconductors: DNTT-C10 and BTBT-C12

John Northrup — Mon, 26 Nov 2012 00:00:00 -0800

The high mobility measured in alkylated DNTT and BTBT molecules [1,2] raises the possibility that band transport may be achievable in solution processed organic semiconductors. Therefore, an acoustic deformation potential model appropriate for transport in two dimensions was employed to estimate upper limits on the hole mobility of DNTT-C10 [1] and BTBT-C12 [2]. Comparison is made to results for a thin-film pentacene structure. Density functional calculations are employed to determine the values of effective masses, deformation potentials and elastic constants required to calculate the mobility along crystallographic axes.[3] According to the model, scattering by acoustic phonons places an upper limit on room temperature mobility within single crystal regions of these materials in the range 50-90 cm2/Vs. The effective masses calculated for the holes in DNTT-C10 and BTBT-C12 are significantly less than those obtained for thin-film pentacene, and this difference is the origin of the superior mobility. The width (in the direction perpendicular to the plane of transport) of the p-bonded molecular core is identified as an important parameter governing mobility in 2D systems such as these. The affect of alkyl chains on the mobility will be discussed.

[1] K. Nakayama et al, Adv. Mater. 23, 1626 (2011). [2] H. Minemawari et al, Nature 475, 364 (2011). [3] J. E. Northrup, Appl. Phys. Lett. 99, 062111 (2011).

Handheld flow cytometer for rapid pathogen characterization in water

Peter Kiesel, Michael Recht, Marshall Bern and Noble Johnson — Sun, 25 Nov 2012 00:00:00 -0800

Water-quality monitoring is an essential priority for global health. With microorganisms a primary cause for the occurrence of infectious diseases, the concentrations of harmful pathogens should be routinely monitored to maintain microbiological quality control of drinking water. Currently the testing is done in central labs using plate-culture assay techniques which can take up to 24 hours to produce test results. In order to achieve more timely assessment of water quality, PARC is developing a compact and robust platform for rapid pathogen characterization in water. The presented approach is suitable for point-of-need testing and is able to provide test results in less than 20min. The enabling technique is termed “spatially modulated emission” and generates a time-dependent signal as a continuously fluorescing bio-particle traverses a predefined pattern for optical transmission. Correlating the detected signal with the known pattern achieves high discrimination of the particle signal from background noise. In conventional flow cytometry, the size of the excitation area is restricted approximately to the size of the particle. Our method allows a large excitation area to increase the total flux of fluorescence light that originates from a particle. Despite the large excitation area, the mask pattern enables a high spatial resolution which permits independent detection and characterization of near-coincident particles, with a separation (in the flow direction) that can approach the dimension of individual particles. In addition, the concept is intrinsically tolerant to background fluorescence originating from fluorescent components in solution or contaminants on the chip. We have demonstrated pre-concentration of Giardia and Cryptosporidium which allows us to substantially reduce the analyte volume (~1000 times) while keeping most of the pathogens (>90%). For the pathogen detection we have assembled and tested a working prototype of a microfluidic based flow cytometer which allows analyzing water samples with a throughput of 50ul/min. Measurements of the sensitivity and dynamic range were conducted with calibration particles and yielded a detection limit of ~500 MEPE, which clearly meets the requirements for a wide range of bio-particle-detection applications. Tests with water-borne pathogens clearly show that this instrument can be used to reliably identify and count specifically-tagged pathogens at very low concentrations. We will show results for Giardia, Cryptosporidium, and E.coli. Incubation studies with antibody-based reagents showed that for Giardia incubation times as short as 2 min and analyte-to-reagent ratios as low as 1:100 are sufficient for reliable detection. We will also show that the antibody-based reagents are highly stable, with little degradation over a period of months at 37C. Acknowledgment: This project is partially funded by the U.S. Army Research Office

The value of rapid ethnography

Ellen Isaacs — Thu, 01 Nov 2012 00:00:00 -0700

In the business world, time is a precious commodity and a tough master. Time is present either explicitly or as an undercurrent in almost every plan or business decision. For ethnographers working in such an environment, fieldwork schedules that once mirrored annual agricultural cycles now must align with the business quarter. While surely requiring tradeoffs, rapid ethnography brings the ethnographic perspective into organizations in a way that is culturally palatable and gives ethnographers a seat at the table. In a corporate setting ethnographers tend to act as the company's scouting party, to understand consumers' needs, to make sense of their evolving practices and to explain why those practices matter to the company's strategy and to the design of its products and services. This paper describes how rapid ethnography was used in three projects, each with its own analytic focus, methods, and lessons learned.

Solving inverse configuration space problems by adaptive sampling

Saigopal Nelaturi — Mon, 29 Oct 2012 00:00:00 -0700

Given two shapes in relative motion, an important class of inverse configuration problems is solved by determining relative configurations that maintain set-inclusion relationships (non-interference, containment, or contact) between the shapes. This class of inverse problems includes the well-known problem of constructing a configuration space obstacle, as well as many other problems in computational design such as sweep decomposition, accessibility analysis, and dynamic packaging. We show that solutions to such problems may be efficiently approximated directly in the 6D configuration space SE(3) of relative motions by adaptive sampling. The proposed method relies on a well-known fact that the manifold of the group SE(3) is a Cartesian product of two manifold subgroups: the group of rotations SO(3) and the group of translations R3. This property allows generating desired configurations by combining samples that are generated in these subgroups independently and adaptively. We demonstrate the effectiveness of the proposed approach on several inverse problems including the problem of sweep decomposition that arises in reverse engineering applications.

An analysis of how ensembles of collective classifiers improve predictions in graphs

Hoda Eldardiry — Mon, 29 Oct 2012 00:00:00 -0700

We present a theoretical analysis framework that shows how ensembles of collective classifiers can improve predictions for graph data. We show how collective ensemble classification reduces errors due to variance in learning and more interestingly inference. We also present an empirical framework that includes various ensemble techniques for classifying relational data using collective inference. The methods span single- and multiple-graph network approaches, and are tested on both synthetic and real world classification tasks. Our experimental results, supported by our theoretical justifications, confirm that ensemble algorithms that explicitly focus on both learning and inference processes and aim at reducing errors associated with both, are the best performers.

BiasTrust: teaching biased users about controversial topics

Peter Pirolli — Mon, 29 Oct 2012 00:00:00 -0700

Deciding whether a claim is true or false often requires understanding the evidence supporting and contradicting the claim. However, when learning about a controversial claim, human biases and viewpoints may affect which evidence documents are considered \"trustworthy\" or credible. It is important to overcome this bias and know both viewpoints to get a balanced perspective. In this paper, we study various factors that affect learning about the truthfulness of controversial claims. We designed a user study to understand the impact of these factors. Specifically, we studied the impact of presenting evidence with contrasting viewpoints and source expertise rating on how users accessed the evidence documents. This would help us optimize how to teach users about controversial topics in the most effective way, and to design better claim verification systems. We find that users do not seek contrasting viewpoints by themselves, but explicitly presenting contrasting evidence helps them get a well-rounded understanding of the topic. Furthermore, explicit knowledge of the source credibility and the context not only affects what users read, but also how credible they perceive the document to be.