How long do people take to react to smartphone notifications?

Notifications are one of the most essential features of smartphones. App developers and researchers typically want to reach their audience at opportune times. We analyzed almost 10 million notifications collected from 922 users. Most notifications were logged in the late morning and late afternoon. Between 8 pm and 11 pm, the interaction delay (time between … Read more

Sentiments about Mental Health on Twitter – Before and during the COVID-19 Pandemic

The COVID-19 pandemic not only affected the respiratory system, but, together with measures like social distancing, potentially affected the mental health of millions of people. What do Twitter (X) users talk about when they talk about #MentalHealth and #Depression? Did it change through the pandemic? We collected almost 3,000,000 tweets from more than 300,000 Twitter … Read more

Mobile Sensing in Personality Science

How can mobile sensing, using the smartphone’s sensors for recording and storing data, help in personality science? Read our comprehensive book chapter on this topic. We cover an overview of related work and show the differences in researching personality traits vs. personality states with mobile sensing. We showcase a concrete mobile-sensing application and provide a … Read more

Social Media App Usage in Relation with PHQ-9 Depression Scores during the COVID-19 Pandemic

With about 300 million affected people, major depressive disorder (MDD) is one of the most common diseases worldwide. During the COVID-19 pandemic, the number of cases increased even further, by 28%. Many factors may be correlated with MDD, including the excessive use of social media apps. We investigated the relationship between the use of social … Read more

Public Perception of the German COVID-19 Contact-Tracing App Corona-Warn-App

Several governments introduced or promoted the use of contact-tracing apps during the ongoing COVID-19 pandemic. In Germany, the related app is called Corona-Warn-App, and by end of 2020, it had 22.8 million downloads. Contact tracing is a promising approach for containing the spread of the novel coronavirus. It is only effective if there is a … Read more

Frequency and duration of daily smartphone usage in relation to personality traits

We investigated associations between personality traits and smartphone usage in daily life. 526 participants (mean age 34.57 years, SD = 12.85, 21% female) used TYDR (Track Your Daily Routine) for 48 days, on average (SD = 63.2, range 2 to 304). The Big Five Inventory 2 (BFI-2) was used to measure personality traits (Extraversion, Agreeableness, … Read more

What data are smartphone users willing to share with researchers?

Expanding on our earlier work on privacy in mobile sensing/data collection apps, we evaluated the data we collected with TYDR. Our experimental evaluation based on the first two month of data collected with TYDR shows evidence that our users accept our proposed privacy model. Based on data about granting TYDR all or no Android system … Read more

Choice Overload and Recommendation Effectiveness in Related-Article Recommendations

Expanding our earlier work on choice overload in related-article recommendations, we analyzed a digital library to figure out the ideal number of recommendations to show to users. Some of our metrics point toward 5-6 items as the ideal number of recommendations to display. You can find the full paper here (PDF). Choice Overload describes a … Read more

Exploring Choice Overload in Related-Article Recommendations in Digital Libraries

We investigate the problem of choice overload – the difficulty of making a decision when faced with many options – when displaying related-article recommendations in digital libraries. So far, research regarding to how many items should be displayed has mostly been done in the fields of media recommendations and search engines. We analyze the number … Read more