Rodrigo de Oliveira

What's up with whatsapp?: comparing mobile instant messaging behaviors with traditional SMS

With the advent of instant mobile messaging applications, traditional SMS is in danger of loosing its reign as the king of mobile messaging. Applications like WhatsApp allow mobile users to send real-time text messages to individuals or groups of friends at no cost. While there is a vast body of research on traditional text messaging practices, little is understood about how and why people have adopted and appropriated instant mobile messaging applications. The goal of this work is to provide a deeper understanding of the motives and perceptions of a popular mobile messaging application called WhatsApp and to learn more about what this service offers above and beyond traditional SMS. To this end, we present insights from two studies an interview study and a large-scale survey highlighting that while WhatsApp offers benefits such as cost, sense of community and immediacy, SMS is still considered a more reliable, privacy preserving technology for mobile communication.

TripleBeat: enhancing exercise performance with persuasion

We present TripleBeat, a mobile phone based system that assists runners in achieving predefined exercise goals via musical feedback and two persuasive techniques: a glanceable interface for increased personal awareness and a virtual competition. TripleBeat is based on a previous system named MPTrain. First, we describe TripleBeats hardware and software, emphasizing how it differs from its predecessor MPTrain. Then, we present the results of a runner study with 10 runners. The study compared the runners efficacy and enjoyment in achieving predefined workout goals when running with MPTrain and TripleBeat. The conclusions from the study include: (1) significantly higher efficacy and enjoyment with TripleBeat, and (2) a unanimous preference for TripleBeat over MPTrain. The glanceable interface and the virtual competition are the two main reasons for the improvements in the running experience. We believe that systems like TripleBeat will play an important role in enhancing the exercise experience and in assisting users towards more active lifestyles.

An in-situ study of mobile phone notifications

Notifications on mobile phones alert users about new messages, emails, social network updates, and other events. However, little is understood about the nature and effect of such notifications on the daily lives of mobile users. We report from a one-week, in-situ study involving 15 mobile phones users, where we collected real-world notifications through a smartphone logging application alongside subjective perceptions of those notifications through an online diary. We found that our participants had to deal with 63.5 notifications on average per day, mostly from messengers and email. Whether the phone is in silent mode or not, notifications were typically viewed within minutes. Social pressure in personal communication was amongst the main reasons given. While an increasing number of notifications was associated with an increase in negative emotions, receiving more messages and social network updates also made our participants feel more connected with others. Our findings imply that avoiding interruptions from notifications may be viable for professional communication, while in personal communication, approaches should focus on managing expectations.

MoviPill: improving medication compliance for elders using a mobile persuasive social game

Medication compliance is a critical component in the success of any medical treatment. However, only 50% of patients correctly adhere to their prescription regimens. Mobile and ubiquitous technologies have been proposed to tackle this challenge, mainly in the form of memory aid solutions that remind patients to take their pills. However, most of these methods do not engage patients in shifting their behavior towards better compliance. In this paper, we propose and evaluate a mobile phone-based game called MoviPill that persuades patients to be more adherent to their medication prescription by means of social competition. In a 6-week user study conducted with 18 elders, the use of MoviPill improved both their compliance to take the daily medication and also the accuracy of the drug intake time according to the prescribed time. Moreover, the improvement in the latter increased from 43% to 56% when we considered only participants that had any interest in games, which reveals the importance of applying persuasive techniques in a personalized manner. We conclude with a set of implications for the design of persuasive mobile solutions in this domain.

Didn't you see my message?: predicting attentiveness to mobile instant messages

Mobile instant messaging (e.g., via SMS or WhatsApp) often goes along with an expectation of high attentiveness, i.e., that the receiver will notice and read the message within a few minutes. Hence, existing instant messaging services for mobile phones share indicators of availability, such as the last time the user has been online. However, in this paper we not only provide evidence that these cues create social pressure, but that they are also weak predictors of attentiveness. As remedy, we propose to share a machine-computed prediction of whether the user will view a message within the next few minutes or not. For two weeks, we collected behavioral data from 24 users of mobile instant messaging services. By the means of machine-learning techniques, we identified that simple features extracted from the phone, such as the users interaction with the notification center, the screen activity, the proximity sensor, and the ringer mode, are strong predictors of how quickly the user will attend to the messages. With seven automatically selected features our model predicts whether a phone user will view a message within a few minutes with 70.6% accuracy and a precision for fast attendance of 81.2%

Understanding near-duplicate videos: a user-centric approach

Popular content in video sharing web sites (e.g., YouTube) is usually duplicated. Most scholars define near-duplicate video clips (NDVC) based on non-semantic features (e.g., different image/audio quality), while a few also include semantic features (different videos of similar content). However, it is unclear what features contribute to the human perception of similar videos. Findings of two large scale online surveys (N = 1003) confirm the relevance of both types of features. While some of our findings confirm the adopted definitions of NDVC, other findings are surprising. For example, videos that vary in visual content - by overlaying or inserting additional information - may not be perceived as near-duplicate versions of the original videos. Conversely, two different videos with distinct sounds, people, and scenarios were considered to be NDVC because they shared the same semantics (none of the pairs had additional information). Furthermore, the exact role played by semantics in relation to the features that make videos alike is still an open question. In most cases, participants preferred to see only one of the NDVC in the search results of a video search query and they were more tolerant to changes in the audio than in the video tracks. Finally, we propose a user-centric NDVC definition and present implications for how duplicate content should be dealt with by video sharing websites.

Money walks: a human-centric study on the economics of personal mobile data

In the context of a myriad of mobile apps which collect personally identifiable information (PII) and a prospective market place of personal data, we investigate a user-centric monetary valuation of mobile PII. During a 6-week long user study in a living lab deployment with 60 participants, we collected their daily valuations of 4 categories of mobile PII (communication, e.g. phonecalls made/received, applications, e.g. time spent on different apps, location and media, e.g. photos taken) at three levels of complexity (individual data points, aggregated statistics and processed, i.e. meaningful interpretations of the data). In order to obtain honest valuations, we employ a reverse second price auction mechanism. Our findings show that the most sensitive and valued category of personal information is location. We report statistically significant associations between actual mobile usage, personal dispositions, and bidding behavior. Finally, we outline key implications for the design of mobile services and future markets of personal data.

Rat subcutaneous tissue response to macrogranular porous anorganic bovine bone graft

The ideal bone graft must present biocompatibility, osteoconductive and osteoinductive properties, resistance and plasticity. Xenogenic grafts of bovine cancellous bone origin are particularly interesting due to their biologically designed porous structure that enhance both cellular and vascular invasion. The purpose of this study was to evaluate the tissue response induced by bovine macrogranular porous anorganic bone implanted in rat subcutaneous tissue. Forty rats were assigned to 2 groups, as follows: the control group received empty collagen capsules and the test group received subcutaneous implants of the test material. Samples were collected after 10, 20, 30 and 60 days and processed histologically. Histological analysis showed at 10 days a granulomatous inflammatory infiltrate, rich in multinucleated giant cells and free of lymphocytes or plasma cells, similarly to mineralized allograft implanted in rat subcutaneous. In later periods, there was a significant decrease in the inflammatory infiltrate and an increase in fibrosis around graft particles. In conclusion, the test material induced a foreign body-type granuloma with subsequent fibrosis around the graft particles implanted in rat subcutaneous and did not elicit any immune response, thus being considered biocompatible.

The role of tags and image aesthetics in social image search

In recent years, there has been a proliferation of consumer digital photographs taken and stored in both personal and online repositories. As the amount of user-generated digital photos increases, there is a growing need for efficient ways to search for relevant images to be shared with friends and family. Text-query based search approaches rely heavily on the similarity between the input textual query and the tags added by users to the digital content. Unfortunately, text-query based search results might include a large number of relevant photos, all of them containing very similar tags, but with varying levels of image quality and aesthetic appeal. In this paper we introduce an image re-ranking algorithm that takes into account the aesthetic appeal of the images retrieved by a consumer image sharing site search engine (Googles Picasa Web Album). In order to do so, we extend a state-of-the-art image aesthetic appeal algorithm by incorporating a set of features aimed at consumer photographs. The results of a controlled user study with 37 participants reveal that image aesthetics play a varying role on the selected images depending on the query type and on the user preferences.

Social tagging revamped: supporting the users' need of self-promotion through persuasive techniques

People share pictures online to increase their social presence. However, recent studies have shown that most of the content shared in social networks is not looked at by peers. Proper metadata can be generated and used to improve the retrieval of this content. In spite of this, we still lack solutions for collecting valid descriptors of content that can be used effectively in the context of social information navigation. In this paper, we propose a mechanism based on persuasive techniques to support peers in providing metadata for multimedia content that can be used for a persons self-promotion. Through an iterative design and experimentation process, we demonstrate how this methodology can be used effectively to increase ones social presence thus building more enjoyable, rich, and creative content that is shared in the social network. In addition, we highlight implications that inform the design of social games with a purpose.