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How should an optimaluser interface ofa first aid app look like?Software-ergonomic conclusions from a “realistic” usability studywith the smartphoneapp “Defi Now!” Karin Harbusch & Janine PaschkeUniversity of Koblenz-LandauDepartment of Computer Science {harbusch, jpaschke}




First Aid Applications

Usability Study


Improved User Interface


1 motivation1

1. Motivation

  • Results in waiting for someone else to take command;

  • Originates from the tendency to belittle the existing emergency since no one has intervened so far;

  • The fear to fail or of humiliation detains many people to help, especially in situations that they are unable to judge.


Individuals are less willing to offer help the more bystanders are present in case of an emergency. This diffusion of responsibility:

1 motivation2

1. Motivation

  • Results in waiting for someone else to take command;

  • Originates from the tendency to belittle the existing emergency since no one has intervened so far;

  • The fear to fail or of humiliation detains many people to help, especially in situations that they are unable to judge.


Individuals are less willing to offer help the more bystanders are present in case of an emergency. This diffusion of responsibility:

Would information provided by an

app help to diminish those fears?

Some background information

Some background information

Sudden cardiac arrest is the most common cause of death in most Western countries and a major cause of hospital admissions.

When suffering from cardiac arrest immediate help, esp.cardiopulmonaryresuscitation (CPR), is essential and a defibrillation is mostly inevitable—nowadays, automatic external defibrillators (AEDs) are provided at many public places.

Average survival rates of 30% for defibrillation by first responders within 3 to 5 minutes are reported. The chance of survival decreases 10% by the minute when no help is provided.

2 first aid apps

2. First Aid Apps

In the following, we illustrate desirable features of six apps that focus on first aid in case of cardiac arrest:

Defi Graz ( (Austria); interface only in German);

ArrêtCardiaque 2.0 ( (France); multilingual interface);

AED Locator ( (Germany); in German);

Defi Now! ( (Germany); multilingual interface);

Herzsicher( (Switzerland); in German);

PulsePoint( (United States); in English).

Features of defi now

Features of ``DefiNow!“

The interface language of “Defi Now!” is automatically adjusted to the user’s phone settings.

Pressing the button “Emergency Call” automatically activates the national emergency phone number adapted to the user’s whereabouts. However, the button does not immediately dial the emergency number because the rescuer has to confirm first by pressing “Yes” in response to the question whether they actually want to place the emergency call—in order to avoid hoax calls.

While placing the call, the current address is displayed to the user so that foreigners (and nervous rescuers) can easily provide the location’s precise address (in Germany, GPS data are not automatically sent).

By pressing the button “First Aid Measures”, first aid procedures are displayed in the form of a diagram.

First aid diagram in defi now
First Aid Diagram in ``DefiNow!“

Do not try to read

but only estimate

the proportion of text

vs. graphics

Would you have noticed this loop?

Supporting cardiopulmonary resuscitation

Supporting Cardiopulmonary Resuscitation

Menu at the bottom of the First Aid Screen:

A metronome provides audio support for a resuscitation beat of 100 times per minute, with an option to administer mouth-to-mouth/-nose respiration. If the patient shows no vital signs, the rescuer receives information on how to perform CPR.

Interesting features of the other apps

Interesting features of the other apps

Graphically oriented support to first aid

Permanently visible tabulator-based interface

Social-network integration: The app may be connected with the user’s Facebook and/or Twitter account to share the AED they registered with their network. Moreover, you communicate that you are a first responder.

3 usability study

3. Usability Study


Some of the features we outlined above (e.g., graphics) are obviously very suitable to make a first aid app supportive for a rescuer.

Norms, style guides from the literature in Human-Computer Interaction give more hints. Also learn from best practices (cf. interesting features of other First Aid apps on previous slide).

However, detailed insights

into unexpected problems

require a usability study.

Induced agitation

Induced Agitation

When witnessing an emergency situation, bystanders and rescuers usually show signs of emotional stress. In order to simulate this stress, we applied a psychological technique to induce agitation:

Watching a short sequence of a movie can elicit high levels of agitation in test participants due to the high attention and the intensive experience tied to watching a film clip.

In our experiment, a film clip was selected from the movie “The Shining” (1980), showing a playing child who heads towards a closed hotel room door. The viewer obtains a feeling that something terrifying is lurking behind the closed door.

Test setup

Test Setup

In total, we tested 74 participants, 35 female/39 male:

With nine students, we had run a pilot study in an observation lab.

Another eight participants were doctors or qualified medical employees.

The other 57 participants were recruited as patients in the waiting room of a doctor’s office or as customers of a fitness center where we had reserved a separate room to perform the experiment.

In order to study the effect of agitation, only half of the the participants watched the film clip before using the app.



The experiment consisted of three parts:

An introductory questionnaire asked questions concerning factors known to influence precision of task execution (e.g. discomforts such as high blood pressure and/or use of medication or emotional state such as happiness or grief).

Nine tasks to be performed/handling has been judged.

Final questionnaire.

Experiment step 2

Experiment – Step 2

The test subjects had to perform nine tasks covering all features of the application “Defi Now!”.

After each task, the study participants had to judge the given features by means of a five-stepped rating-scale, ranging from 1=”not applicable at all” to 5=”completely applicable”.

Moreover, they could spontaneously mention what they (dis-)liked about any provided feature.

Experiment step 3

Experiment – Step 3

Final questionnaire asking general questions such as:

Whether owning a smartphone themselves;

Whether finding spoken instructions in the app helpful, especially with respect to administering first aid.

Whether/When they attended their last first aid course, and whether they judged a first aid app useful in case of emergencies such as cardiac arrest.



Influence of (induced) stress

The film clip induced emotional states comparable to those reported by Schleicher (2009).

However, we could not observe any significant effect on the execution of the “Defi Now!” tasks.

Participant selection

We found no significant differences between the student group, the medically trained personnel and the other participants.

They all had similar problems with the same features of the user interface.

Results for questionnaire 1 cont

Results for Questionnaire 1 (cont.)

Influence of personal factors

With respect to their physical condition, 84% declared they did not suffer from any health problems. From the 16% who mentioned health problems, one participant used tranquillizers, two had a common cold, five are high-blood- pressure patients and three had problems with their cervical spine. Analysis of the video data and the participants’ behavior, lead to the conclusion that some discomforts as well as specific medication could affect a person’s performance.

However, the physical condition of a participant had no influence on their emotional state.

Results for step 2 cont

Results for Step 2 (cont.)

Reviewing the diagram “First Aid Measures“

57% stated that they knew which first aid step to perform next, at all times.

Only 12% felt uncertain about possible next steps,

19% judged the diagrams as unsuitable and wanted more detailed instructions.

On the other hand, 64% declared the diagrams suitable for learning, since they immediately understood the proper sequence of first aid procedures to be carried out in case of an emergency.

Results for step 2 cont1

Results for Step 2 (cont.)

Reviewing the diagram “First Aid Measures“ II

When asked whether they saw the circular symbol in the diagram, 64% of the participants denied.

21% searched for the mentioned symbol on request and found it after an average of 7.6 seconds.

Merely 16% of the participants had detected the circular symbol spontaneously.

Twelve participants stated here that they would appreciate spoken statements or a combination of speech and graphics/text. Eight participants criticized the wording used in the diagrams.

Results for step 2 cont2

Results for Step 2 (cont.)

CPR rhythm and CPR mode (with or without artificial respiration)

32% of the participants recognized the trigger of the metronome immediately.

41% had difficulties and pressed the button predefining the resuscitation beat only after an average of 6.3 seconds.

5% initiated the beat after more than 10 seconds.

23% saw the trigger only after instruction.

As for overall comments: - 58% expressed the desire for more directions given by the

application itself.

- 47% suggested that the trigger should be placed next to the

graphics depicting the CPR procedure.

Improved interface1

Improved Interface navigation

Clarify that there is a CPR choice (default option highlighted in red)

Improved interface2

Improved Interface navigation

Focus attention on repetition

Improved interface3

Improved Interface navigation

Clarify that metronome can be switched on/off


Conclusions navigation

We reported the results of a

close-to-realistic usability study

with the “Defi Now!” app. We motivated some improvements

of the user interface.

Future work

We want to experiment with more speech driven systems.

We want to test social media driven distribution of First Aid knowledge or becoming first responder.

We want to develop First Aid training apps in a challenging manner as is a goal in game-based learning.

Merci beaucoup pour votre attention navigation!

Thank you for your attention!