Can small be beautiful? assessing image resolution requirements for mobile TV

Mobile TV services are now being offered in several countries, but for cost reasons, most of these services offer material directly recoded for mobile consumption (i.e. without additional editing). The experiment reported in this paper, aims to assess the image resolution and bitrate requirements for displaying this type of material on mobile devices. The study, with 128 participants, examined responses to four different image resolutions, seven video encoding bitrates, two audio bitrates and four content types. The results show that acceptability is significantly lower for images smaller than 168×126, regardless of content type. The effect is more pronounced when bandwidth is abundant, and is due to important detail being lost in the smaller screens. In contrast to previous studies, participants are more likely to rate image quality as unacceptable when the audio quality is high

From protest to agenda building: Description bias in media coverage of protest events in Washington, D.C

Social movements often seek to draw attention to issues they deem important by organizing public demonstrations with the aim of attracting mass media coverage. But only a small proportion of all public demonstrations receives any media attention. This article asks whether even the minimal coverage that demonstrations receive reveal any influence of social movements in shaping how issues are framed by the mass media. Analyzing newspaper and television news stories on Washington, D.C. protests held during 1982 and 1991, we ask whether news reports on protests are framed in ways consistent with the aims of protesters. Do demonstrators receive media coverage that highlights the issues about which they are concerned, or does coverage focus on the protest event itself, to the exclusion of the social issues that movements target? Our results support much of the surmising among media scholars, that even when movements succeed at obtaining the attention of mass media outlets, media reports portray protests in ways that may undermine social movement agendas. Despite this obstacle to communicating protest messages through demonstrations, movements engage in other forms of communication that can affect public interpretations of mass media frames

Rich Media, Poor Judgement? A Study of Media Effects on Users’ Trust in Expertise

In this paper, we investigate how interpersonal cues of expertise affect trust in different media representations. Based on a review of previous research, richer representations could lead either to a positive media bias (P1) or increased sensitivity for cues of expertise (P2). In a laboratory study, we presented 160 participants with two advisors - one represented by text-only; the other represented by one of four alternate formats: video, audio, avatar, orphoto+text. Unknown to the participants, one was an expert (i.e. trained) and the other was a non-expert (i.e. untrained). We observed participants' advice seeking and advice uptake to infer their sensitivity to correct advice in a situation of financial risk. We found that most participants preferred seeking advice from the expert, but we also found a tendency for seeking audio and in particular video advice. Users' self-reports indicate that they believed that video in particular would give them the most detailed insight into expertise. Data for advice uptake, however, showed that all media representation, including text-only, resulted in good sensitivity to correct advice

Trust at First Sight? A Test of Users' Ability to Identify Trustworthy E-Commerce Sites

Consumer trust in e-commerce is a key concern in current HCI research. In this paper, we report a study that investigated (1) if users can correctly identify trustworthy vendors based on cues they perceive in the interface. A further aim was to test (2) if users’ judgement can be influenced by the introduction of an affective element — an employee photo. Since such elements have been reported to have negative effects on usability, we also checked for (3) effects of the photo on users’ visual gaze pattern and task performance when interacting with the sites. At first sight of a page, users’ ability to identify trustworthy vendors was not better than chance. Only after detailed exploration could users reach correct trust decisions. A photo only had an effect on participants’ first impression of a vendor. We did not find effects of the photo on task performance

The Eyes Never Lie: The Use of Eyetracking Data in HCI Research

Recent technology developments have made eye-tracking systems more affordable and less cumbersome. Many members of the HCI community will therefore consider employing this method in usability research and assessment. This paper, provides an overview of the eye movement data that can be collected, what is involved in analysing them, and what it can add to current HCI research and usability assessment practice. We argue that, whilst much work is required to develop the use of eyetracking as a practitioner’s method, it can provide valuable objective data about the impact of visual design on human performance. To illustrate this point, some preliminary results of a study into web page usage are reported. The results are examined with regard to explaining task performance, user physiology as well as in the assessment of the difficulties and the potential behind eye-tracking

Trust in Mediated Interactions

This article presents a brief overview of the background of trust research and its relevance. It then introduces a framework for trust in mediated interactions that draws on existing models and findings, and applies this to human trust in other humans, organizations (e.g., e-commerce vendors), and technology (e.g., websites). Beyond incorporating variables related to the trusting and the trusted actor, the framework accommodates key contextual factors. Rather than treating trustworthiness as a relatively stable attribute of the trusted actor, the framework considers how trustworthiness is influenced by these contextual factors. This framework will help researchers in aligning disparate research findings and it may be a step towards building a theory of trust in human-computer interactions. For designers, the benefit lies in helping them to fully explore the available design space of systems fostering trust in mediated interactions

Do people trust their eyes more than their ears? media bias while seeking expert advice

Enabling users to identify trustworthy actors is a key design concern in online systems and expertise is a core dimension of trustworthiness. In this paper, we investigate (1) users' ability to identify expertise in advice and (2) effects of media bias in different representations. In a laboratory study, we presented 160 participants with two advisors-one represented by text-only; the other represented by one of four alternate formats: video, audio, avatar, or photo+text. Unknown to the participants, one was an expert (i.e. trained) and the other was a non-expert (i.e. untrained). We observed participants' advice seeking behavior under financial risk as an indicator of their trust in the advisor. For all rich media representations, participants were able to identify the expert, but we also found a tendency for seeking video and audio advice, irrespective of expertise. Avatar advice, in contrast, was rarely sought, but-like the other rich media representations-was seen as more enjoyable and friendly than text-only advice. In a future step we plan to analyze our data for effects on advice uptake

Reading the Fine Print: the Effect of Text Legibility on Perceived Video Quality in Mobile TV

Mobile TV services are available in an increasing number of countries. For cost reasons, most of these services offer material directly recoded for mobile consumption (i.e. without additional editing). This paper reports the findings of a study on the influence of text legibility and quality on the perceived video quality of mobile TV content. The study, with 64 participants, examined responses to news footage presented at four image resolutions and seven video encoding bitrates. The results showed that a simulated separate delivery of a news ticker and other textual information significantly increased the perceived video quality of the entire screen for native speakers. In addition, some automatable changes to the layout of news content resulted in substantial increases in perceived video quality. The results can be used to quantify the perceived quality gains when considering text delivery separately from the video stream and in the development of more accurate multimedia quality models

Senile Systemic Amyloidosis: Clinical Features at Presentation and Outcome

Background Cardiac amyloidosis is a fatal disease whose prognosis and treatment rely on identification of the amyloid type. In our aging population transthyretin amyloidosis (ATTRwt) is common and must be differentiated from other amyloid types. We report the clinical presentation, natural history, and prognostic features of ATTRwt compared with cardiac‐isolated AL amyloidosis and calculate the probability of disease diagnosis of ATTRwt from baseline factors. Methods and Results All patients with biopsy‐proven ATTRwt (102 cases) and isolated cardiac AL (36 cases) seen from 2002 to 2011 at the UK National Amyloidosis Center were included. Median survival from the onset of symptoms was 6.07 years in the ATTRwt group and 1.7 years in the AL group. Positive troponin, a pacemaker, and increasing New York Heart Association (NYHA) class were associated with worse survival in ATTRwt patients on univariate analysis. All patients with isolated cardiac AL and 24.1% of patients with ATTRwt had evidence of a plasma cell dyscrasia. Older age and lower N‐terminal pro‐B‐type natriuretic peptide (NT pro‐BNP) were factors significantly associated with ATTRwt. Patients aged 70 years and younger with an NT pro‐BNP <183 pmol/L were more likely to have ATTRwt, as were patients older than 70 years with an NT pro‐BNP <1420 pmol/L. Conclusions Factors at baseline associated with a worse outcome in ATTRwt are positive troponin T, a pacemaker, and NYHA class IV symptoms. The age of the patient at diagnosis and NT pro‐BNP level can aid in distinguishing ATTRwt from AL amyloidosis

Genetic diversity of Campylobacter jejuni and Campylobacter coli isolates from conventional broiler flocks and the impacts of sampling strategy and laboratory method

The genetic diversity of Campylobacter jejuni and Campylobacter coli isolates from commercial broiler farms was examined by multilocus sequence typing (MLST), with an assessment of the impact of the sample type and laboratory method on the genotypes of Campylobacter isolated. A total of 645 C. jejuni and 106 C. coli isolates were obtained from 32 flocks and 17 farms, with 47 sequence types (STs) identified. The Campylobacter jejuni isolates obtained by different sampling approaches and laboratory methods were very similar, with the same STs identified at similar frequencies, and had no major effect on the genetic profile of Campylobacter population in broiler flocks at the farm level. For C. coli, the results were more equivocal. While some STs were widely distributed within and among farms and flocks, analysis of molecular variance (AMOVA) revealed a high degree of genetic diversity among farms for C. jejuni, where farm effects accounted for 70.5% of variance, and among flocks from the same farm (9.9% of variance for C. jejuni and 64.1% for C. coli). These results show the complexity of the population structure of Campylobacter in broiler production and that commercial broiler farms provide an ecological niche for a wide diversity of genotypes. The genetic diversity of C. jejuni isolates among broiler farms should be taken into account when designing studies to understand Campylobacter populations in broiler production and the impact of interventions. We provide evidence that supports synthesis of studies on C. jejuni populations even when laboratory and sampling methods are not identical