Back to the App:The Costs of Mobile Application Interruptions

Luis A. Leiva1, Matthias Böhmer2, Sven Gehring2, Antonio Krüger2

1 Universitat Politècnica de València // Institut Tecnològic d'Informàtica2 DFKI // Ubiquitous Media Technology Lab

Mobile phones evolved from communication devices...

... to devices supporting various tasks.

What are the costs of app interruptions?- When switching between applications?- When being interrupted by a phone call?

In this note...

‣We present a framework for detecting interruptions from mobile app usage logs

‣We investigate the costs and frequency of app interruptions- Intentional app-switching behavior- Interruptions by incoming phone calls

‣We discuss strategies for mitigating interruptions

Study Dataset

3.6K unique users

15.7K different apps

1.5 years

5.5M data samples

Detecting Interruptions

...app use...time

‣App use contained in log file- Timestamp of start of use- Duration of use

‣We keep track of usage time of apps

app use

Detecting Interruptions

...... app use cont‘dinterruption

‣Mining for interruptions- Internal interruptions: another application- External interruptions: incoming phone call

‣We know the duration of the interruption

time

Measuring Interruptions

app useRuntime of non-interrupted apptime

Duration of interrupted app use app use app use cont‘dtime

Duration of interruption interruptiontime

Duration of overheadoverhead

app use app use cont‘d

app use

time

‣ Internal interruptions are more frequent and involve more apps

‣Our analysis is based on paired cases

Study Results

external internal

Interruption data samples 776,922 970,543Interrupted users 1,929 [1,676] 2,926 [2,609]

Interrupted Applications 1,373 [487] 4,626 [1,043][paired samples denoted in brackets]

Occurrences of App Interruptions

‣ Interruptions do not happen as often as expected- 3% of app use is interrupted by phone calls (external)- 8% of app use is interrupted by app switching (internal)

external internal

Daily interruptions (% usage) 3.2 (2.2) 8.3 (5.3)per user

Interrupted applications 3.3 (2.6) 8.7 (7.2)per user

mean (SD)

Impact of App Interruptions

‣ If interruptions happen, resumption costs may be exceedingly high

external internal

Regular app runtime (s) 24.8 (31.8) 18.9 (24.4)

per appRuntime when interrupted (s) 107.1 (121.1) 87.9 (75.5)

per appInterruption duration (s) 12.5 (8.1) 23.7 (19.3)

per app

Overhead duration (s) 43.2 (65.9) 34.4 (40.7)

per app

mean (SD)

‣ Help to regain context of deferred application when resumed, inspired by previous approaches in field of desktop interruptions

‣ Preventive: Prepare user for being interrupted- Postponing phone call for a few milliseconds- Gradually overlaying phone call instead of full-screen popup

‣ Curative: Guide user back into task- Replaying last milliseconds of UI interactions- Leave visual cues on screen to hint where to continue- Vanish interruptive application into point of last focus

Design Implications

Conclusion

‣Main Findings:- Application interruptions are happening rarely- If interruptions happen, they are costly- App-switching behavior is not as often as assumed- Call interruptions add significant overhead to app use

‣ Future Work:- Enriching data collection process with experience sampling

methods to get more insights into context of interruptions- Model for predicting interruption overhead to inform the

means of curation

‣Thank you :-)