Didn’t you see my message?! (CHI ’14)

“Didn’t you see my message?!”

For the younger generations, not receiving a timely response to a SMS or message is a major source of irritation and frustration.

However, people cannot or do not want to always attend to their phones all the time.

What if your phone would infer these situations and communicate them to your friends?

Only how would the phone know?

Our research at Telefonica Research shows that these predictions can be done by simply monitoring a phone’s screen status (on/off), ringer mode, proximity sensor, the hour of the day, and when the user last visited the notification center.

In a user study, where we tried the system with 24 participants over 2 weeks, we learned that half of the messages are viewed within 6.15 minutes, and the other half after that.

A machine-learning model created on the basis of this data can predict with an accuracy of 70.6% whether a message will be viewed within 6 minutes or later. If the prediction is that the message is going to be viewed within those 6.15 minutes, it is even more conservative: the precision of the model is 81.2% in this case.

This research will be presented at the ACM CHI Conference on Human Factors in Computing Systems, held in Toronto, Canada in May 2014.

Martin Pielot, Rodrigo de Oliveira, Haewoon Kwak, Nuria Oliver
Didn’t You See My Message? Predicting Reactiveness in Mobile Instant Messaging
Proc. CHI ’14 Conference on Human Factors in Computing Systems, ACM, 2014.

Telefonica Research at CHI ’14

Telefonica Research will be represented with 2 full papers and 2 ToCHI articles at ACM CHI ’14, the premier international conference of Human-Computer Interaction.

Didn’t You See My Message?

Martin Pielot, Rodrigo de Oliveira, Haewoon Kwak, Nuria Oliver

We found that monitoring the phone (screen activity, notification center access, proximity sensor, ringer mode) allows to predict whether a person will attend to a received message fast or not (pdf).

A brief but more detailed description can be found in in more recent blog post.

Large-scale assessment of mobile notifications

Alireza Sahami Shirazi, Niels Henze, Martin Pielot, Dominik Weber, Albrecht Schmidt

As part of the study, we published an Android app on Google Play that forwards all phone notifications to the browser (via plugin). More than 40,000 people thought this was a brilliant idea and downloaded the app. We used the app as a vehicle to log and analyze all notifications that users receive (pdf).

A Large-scale Study of Daily Information Needs

Karen Church, Mauro Cherubini, Nuria Oliver

My colleagues have conducted one of the most comprehensive studies of information needs to date. For three months, they probed information needs via experience sampling and daily diaries, to understand “the types of needs that occur from day to day, how those needs are addressed and how contextual and demographic factors impact on those needs” (details on Karen’s website.)

Influence of Personality on Satisfaction with Mobile Phone Services

Rodrigo de Oliveira, Mauro Cherubini, Nuria Oliver

My colleagues connected the phone use habits of 603 volunteers with personality traits and customer satisfaction, and found that “(1) extroversion, conscientiousness, and intellect have a significant impact on customer satisfaction—positively for the first two traits and negatively for the latter; (2) extroversion positively influences mobile phone usage; and (3) extroversion and conscientiousness positively influence the users’ perceived usability of mobile services” (ACM Digital Library).

Telefonica Research Barcelona is hiring

My lab is hiring:

The Telefonica Digital Research group was created in 2006 and follows an open research model in collaboration with Universities and other research institutions, promoting the dissemination of scientific results both through publications in top-tier peer-reviewed international journals and conferences and technology transfer. Its multi-disciplinary and international team counts with about 20 full time researchers, holding PhD degrees in various disciplines of computer science and electrical engineering.

The group is seeking candidates for Internships, PostDoc and Researcher (at different levels of seniority) positions to strengthen and complement our efforts in the areas it currently works on:

- Big Data Analysis
- Distributed systems and networking
- Human–computer interaction
- Machine Learning
- Mobile computing
- User modelling and Recommender Systems
- Security and privacy

The salaries offered are competitive and will depend upon the candidate’s experience. The group also offer great benefits and a stimulating and friendly working atmosphere in one of the most vibrant cities in the world, Barcelona (Spain).

You can find more information about the group here:

To apply for a position at Telefonica Research Barcelona, please enter your information into this site:

Applications submitted by February 28th, 2014 will receive full consideration, although applications will continued to be accepted after this date until all positions are filled up.

Open CSV files by double click with Excel 2011 (OS X)

Excel can open and interpret CSV files on double click.

However, for some locales it may happen that all the content appears in the first row.

This is how I fixed it.

Clean up Preferred Languages

In my case, I am using Excel 2011 for OS X 10.9. The CSV was not interpreted correctly, because German appeared in the Preferred languages of the Language & Region settings.

The simple fix was to remove all preferred languages except from English (United States) so that it would become the primary language, and then re-add the other languages.

After that, Excel 2011 flawlessly opened a comma-separated CSV file on double click and distributed the values correctly over the rows.


German, and other languages, use the comma instead of the dot as decimal separator (e.g. 123,45 instead of 123.45). Thus, Excel on German machines expects semicolons to separate values in a CSV file. The fix above will help to work with CSV files in international environments.

Ambient Timer – Unobtrusively Reminding Users of Upcoming Tasks with Ambient Light

Alice is working on a report for the head of her department. At the same time, there is a meeting scheduled in thirty minutes, which she has to attend. The Ambient Timer is already illuminating the wall behind her monitor in a low-attention state, so Alice feels confident that she will be reminded of the meeting. A few minutes before the meeting, the status of the ambient light display has changed to a more salient, intense output. While she is still working on her report, she slowly becomes aware of the nearing deadline and starts finishing the paragraph she is currently working on. One minute before the meeting the light has become so salient that it is hard to ignore. Alice stores the document on the server, puts her computer into sleep mode, and arrives at the meeting on time.


A timer that uses ambient light

The Ambient Timer is a research prototype developed in the Interactive Systems Group of the OFFIS Institute for Information Technology. Its goal is to gently remind information workers about upcoming events. such as illustrated in the scenario above. It uses LED glued to the back of the monitor to illuminate the wall in the peripheral field of vision of the worker.

User Study

With this prototype, we conducted a user study in collaboration with the HCI and Mobile Computing Group of Telefónica Research. We experimentally studied two instances of the Ambient Timer:

  • expo: a gradual change from green to red, becoming exponentially faster, and
  • sinus: a sinusoidal change between red and green which became increasingly faster.

We compared these reminders against two traditional techniques to keep track of appointments:

  • a clock, such as the one in the corner of your computer screen, and
  • a popup alarm, such as when you use Outlook, Lotus Notes, or the OS X Calendar for your appointments.

For the study, we asked participants to copy and correct texts. Meanwhile, a 10-minute timer was running in the background. The task was to finish as many texts as possible in 10 minutes, but without “overshooting”, i.e. having an unfinished text after 10 minutes. In the expo, sinus, and clock conditions, the remaining time was presented by the Ambient Timer or a clock, respectively. In the popup condition, no time was given, but a popup informed the participants 30 seconds before the end of the time limit.

The experiment used a repeated-measures design, i.e. each participant tested each of the four reminder systems in counter-balanced order.


Our results show that participants experienced significantly fewer interruptions when using Ambient Timer in the expo condition, i.e. with an exponential change from green to red, compared to all other reminder techniques in our experiment. Their average typing speed was significantly faster when in this condition, too. Participants ranked this design best, felt most confident using it and preferred it over all other techniques.


This experiment shows that using light in the periphery around the monitor is a great way to provide information workers with information in an ambient way. Used as Ambient Reminder, ambient light might help to structure typical office work, which is often a mix of concentrated desktop work and scheduled meetings and appointments. It allows office worker to avoid to constantly check the clock or be interrupted by alarming popups interrupt.


The details of the experiment have been published in the 14th IFIP TC13 Conference on Human-Computer Interaction, held in September 2013 in Cape Town, South Africa:

Heiko Müller, Anastasia Kazakova, Martin Pielot, Wilko Heuten and Susanne Boll.
Ambient Reminder: Unobtrusively Reminding Users of Upcoming Tasks with Ambient Light.
INTERACT ’13: 14th IFIP TC13 Conference on Human-Computer Interaction, 2013.

Peripheral Vibro-Tactile Displays

If you are sitting, which parts of your body are currently touching the chair? Are you leaning on a backrest or an armrest?

Think about it! Now, you are aware! But have you been just before reading this post? Probably not!

This is the beauty of peripheral perception, i.e. perceiving sensory input in the periphery of our attention. Your brain perfectly knows how to process the touch input it gets from the different parts of your body so that you do not fall of the chair. At the same time, you can perfectly focus on reading this text.

Using our Sense of Touch for Periperphal Communication

But, could this property of our sense of touch also be used to communicate information in the periphery of attention via mobile and ubiquitous computing devices? For example, imagine a bracelet indicating the time remaining until your next appointment, or your mobile phone indicating that there are no unread emails, messages, or social network updates to attend to.

Peripheral Vibro-Tactile Displays

In our research on peripheral, vibro-tactile displays, we made first investigations to prove that such information presentation could be possible with vibration motors, or vibro-tactile displays, as they can be commonly found in our mobile phones.

Study: Exposing People to a Constant Heartbeat

15 participants wore a vibro-tactile display in their pocket for 3 days. The display was set to create a constant, soothing, heartbeat-like vibration pattern. Via mobile phone, the participants adjusted the intensity, so that the vibration was barely perceptible.

Death Events: Testing Awareness

To test whether the vibration was still perceived, it died after 15 to 60 minutes. As soon as the participants noticed, they had to acknowledge the death of the vibration by pressing a button on a mobile phone. In the study, the majority of the death events were noticed between 1 and 10 minutes after the vibration had died. This is an indicator that participants were still aware about the vibration, even though it was set to very low intensities.

Testing Ambientness

To check whether the vibration had left the participants conscious perception, i.e. the focus of attention, we opened a questionnaire on the phone once the participants had pressed the button. In 67.7% of the cases, the participants indicated that the subjectively did not think that they had noticed quickly that the vibration had died. Additionally, in 94.4% of the cases, the participants reported to not be annoyed by the vibration. These two results indicate that the heartbeat vibration was indeed not in the focus, but in the periphery of attention.


These results provide first evidence that vibration patterns can form non-annoying, lightweight information displays, which can be consumed at the periphery of a user’s attention.

However, these findings are only first steps. We need more evidence to back up the findings, and we need more insights into how to adjust the intensity of the vibration pattern to different situations, so that we always hit the sweet spot of being just barely perceptible.


The details of this study will be presented at ACM MobileHCI ’13, the 15th International Conference on Human-Computer Interaction with Mobile Devices and Services, held in August 2013 in Munich, Germany.

Martin Pielot and Rodrigo de Oliveira.
Peripheral Vibro-Tactile Displays.
MobileHCI ’13: 15th International Conference on Human-Computer Interaction with Mobile Devices and Services, 2013.

iPad 4 or iPad Mini?

Planning to buy an iPad?

If you are thinking to join the Apple world of tablet computers, you probably have already thought about whether it should be a Mini or a ‘regular’ iPad.

iPad4 and iPad Mini

In this article, I give some potentially helpful information for your choice: I present my personal experience owing both devices.

My Experiences

The iPad is regularly use are a 16GB iPad 4 with WiFi only, and an iPad Mini with16GB + 3G/GPS module. My analysis is therefore based on these devices.

First of all, the iPad Mini is indeed “every inch an iPad“. If you are using the iPad Mini, you won’t notices that anything is missing. All iPad apps run perfectly. Even Siri is available. And, surprisingly, despite the smaller screen, it never feels too small.

Handling is where the iPad Mini shines. Its reduced size and weight will come in handy in many situations:

  • You can hold it in one hand for a long time without getting tired. The iPad 4, in contrast, quickly starts feeling heavy, thanks to the bigger battery required for the retina display.
  • When writing notes, an email, or a message, the size factor clearly favours the iPad Mini. It’s much easier to hold it with two hands and use the two thumbs for writing – they will much easier reach those keys that are in the middle of the screen.
  • Because it’s lighter and smaller, you will more often find you taking it on your trips. Therefore, you can use it in more situations, which will make it more useful – in particular if you invest into a 3G / GPS upgrade.

Graphics is where the iPad 4 shines. It’s retina display provides an amazing viewing experience. The screen is far more crisp. Once your eye got used to the 264 pixels per inch (ppi), other displays start to look disappointing. Also, when running apps for the iPhone in double-size, the iPad 4 displays them much smoother than the iPad Mini.

Regarding processing speed, the iPad 4 features a faster processor. If you put both devices next to each other and start an activity on both devices at the same moment, you will see that the iPad 4 is a tick faster than the iPad Mini. However, during normal use you will never think that the iPad Mini is slow. The iPad 4′s A6X processor with quad-core graphics might come in handy for hardcore games, but I haven’t yet felt a significant performance difference.

The amazing display of the iPad 4 come with a caveat: it requires a lot of energy, which in consequence creates a lot of heat. You will find the iPad 4 becoming hot much more often than the iPad Mini.


The decision strongly depends on what is important for you. I would slightly favour the iPad Mini, since all-in-all it’s more useful due to its form factor. However, if your main use for the iPad will be the couch, the iPad 4′s retina display makes it the better choice.

Of course, these are all my personal experiences and opinions. For your specific case, other factors might be more important. Yet, The conclusion matches with the reviews appeared on About.com, The Telegraph, and ZDNet.

I Never get the Good One’s! How many Paper to Review?

I never get the good papers for review.

If this thought has ever crossed your mind, you are probably not alone. Good conferences in the HCI field typically accept only 20-25% of the papers submitted for review.

So how many papers to accept for review

… to review at least one good one?

It may seem obvious: the number should depend on the acceptance rate of the conference: 4 papers for 25%, 5 papers for 20%, 6 papers for 16.6%.

So, you are doing this already, and you still seem to get only the to-be-rejected ones?

This is, because probability computation does not always follow the intuitive approach.

Compute by rejection rate

The key is to compute by rejection rates and multiply them per paper.

If you review one paper from a conference with 20% acceptance rate, it’s likelihood to be rejected is 80%.
For two papers from the same conference, the likelihood that both are rejected is 80% * 80% = 64%. (not 60%, as what our intuition might tell us)

The row continues:

  • three papers = 51.2%
  • four papers = 41.0%
  • five papers = 32.8%

So, even if you review five papers in this conference, the likelihood is 32.8% that all of them will be rejected.
See the diagram below for different acceptance rates (25%, 20%, 15%).

Likelihood of Reviewing Accepted Paper by Acceptance Rate of a Conference

Likelihood of Reviewing Accepted Paper by Acceptance Rate of a Conference


So, how many papers to accept for review?

If you want to have a 20% 80% chance of reviewing at least one accepted paper, you have to accept the following number of papers for review:

  • 6 papers for a venue with a 25% acceptance rate
  • 7-8 papers for a venue with a 20% acceptance rate
  • 10 papers for a venue with a 15% acceptance rate


Use 18pt Font Size for Readers with Dyslexia

Dyslexia: a common reading disability

Dyslexia is a neurological reading disability, which impairs a person’s ability to read and write. In the media, we often hear about dyslexia as a gift in the context of famous people, such as Steve Jobs. However, in reality, depending on the language, a significant chunk of the people suffer from dyslexia, e.g. 10 to 17.5% in the US. For most of these, dyslexia is not a gift: the most common way of identifying dyslexia in children is bad performance in our reading-centric education system.

Can the right presentation parameters improve reading?

The good news is that reading increasingly takes place via electronic displays, where we can adapt the presentation of text to make it easier to read for people with dyslexia. Therefore, led by Luz, we (Luz Rello, Martin Pielot, Mari-Carmen Marcos, and Roberto Carlini) set out to find optimal values for the most simple parameters of presentation: font size and line spacing.

Eye-tracking study exploring font size and line spacing

The study was conducted by Luz Rello in the Universitat Pompeu Fabra (UPF) in Barcelona, Spain. 28 people (15f, 13m), aged 14-38, with a confirmed diagnosis of dyslexia took part in the study. They were asked to read Wikipedia articles that were presented with different font sizes and line spacings. The study used eye tracking and questionnaires to measure readability and comprehension.

The experiment compared:

  • Font sizes: 10, 12, 14, 18, 22, and 26 pt.
  • Line spacings: 0.8, 1.0, 1.4, and 1.8.


To make a long story short, line spacing did not have much of an impact. Only 1.8 line spacing lead to worse comprehension compared to 0.8 line spacing.

Regarding font size, however, the results were surprising. When we look for optimal font size in the web, we either find soft recommendations, such as “allow to adjust
or values around 12pt / 14pt.

However, our results provide strong evidence that for people with dyslexia, readability and comprehensibility of a text increases with font size, which an optimum around 18pt.

In particular, we found that:

  • The objective readability, which is indicated by the fixation duration recorded with the eye-tracker, steadily increased until 18pt.
  • The subjective readability was highest for 18pt and 22pt.
  • The subjective comprehensibility was highest for the three largest fonts: 18pt, 22pt, 26pt.

Conclusions: use 18pt font size for your website

Hence, when designing a website that shall be friendly to readers with dyslexia (remember, 10-17.5% of the population!), use large fonts. Since there was no improvement at larger font sizes, 18 pt font size hits the sweet spot.

Complete report

The complete scientific report can be found below.

Luz Rello, Martin Pielot, Mari-Carmen Marcos and Roberto Carlini.
Size Matters (Spacing not): 18 Points for a Dyslexic-friendly Wikipedia.
W4A ’13: 10th International Cross-Disciplinary Conference on Web Accessibility, 2013.

This work was published at the 10th International Cross-Disciplinary Conference on Web Accessibility, held 13-15th May 2013 in Rio de Janeiro, Brazil.


How do Push Notifications Affect our Lives?

Thanks to apps like WhatsApp, Facebook Messenger, or TU Me, we nowadays can send messages for free from phone to phone. Thus, it is no surprise that we exchange more and more messages. For example, on Aug 23, 2012, WhatsApp announced that its users were now sending and receiving 10 Billion messages per day. Assuming around 100m active users, the average user sends and receives 100 messages per day.

This means that the average users receives 50 messages per day. Hence, 50 times per day the phone will notify the user through a ringtone and/or vibration about the received message. And, the phone does not care if its user is in a meeting or hanging our with friends.

So, if we exchange increasingly more messages via mobile phones, how does this affect our lives? Are notifications giving us a new sense of connectedness? Are they dragging us away from the people around us? Are they creating new cultures of social interaction?

At Telefonica Research, we are about to launch a study to shed light on this topic. The good news is
* if you own an Android phone with OS 4.0 (Ice Cream Sandwich) or higher,
* you send and receive a lot of messages via your phone,
* and you don’t mind about being compensated with 40 EUR Amazon Gift Cards,
you can be part of it!

More info about the study and how to sign up can be found here: http://www.surveymonkey.com/s/notifications-study



Thoughts on HCI, Mobile Computing, & co.