This application uses 2 different reaction tests to quantify your level of alertness. From a number of studies it is known that even slight variations in average reaction time, if a random stimulus is given, correlates to diminished vigilance, and sleep depriviation. This Application gives you the ability to regularly assess, analyze, track and compare your psychomotor vigilance using a fun, easy-to-use method.
Introduction: Psychomotor Vigilance
Tests based on reaction time on randomized displayed symbols have been shown in a number of studies to correlate with sleepiness and vigilance (see, for example, this publication and references herein).
For more information on diminished alertness and daytime sleepiness you can visit the website of The American Sleep Association.
Recording
To start a recording, choose the simple reaction time test, ot the “One of Four” test, and hit the start button.
There are 2 different tests:
- Reaction time: a simple reaction time test. A green circle appears for a random time interval. Push the “Hit” button or on the symbol as fast as possible when the red square shows up.
- One of four: a reaction time test based on 4 different symbols. Again, a green circle appears for a random time interval. Now, in addition to the red square, 3 other “disturbance” symbols are presented in random order. Push the “Hit” button or on the symbol as fast as possible ONLY when the red square shows up.
How does it work?
The program stores the reaction time of every trial very accurate (error about 2 milli seconds) and calculates the average value, the average of the 10% best, and the error rate (One of Four only).
Results of the measurements and Saving
If the recording is finished your results are displayed in a color bar chart (see also Interpretation of the Charts). You will see the current measurement results as a marker labeled “New” within the color chart of all previous measurements stored in your iPhone or iPod. Below the bar the “Others” bracket mark the range of other users of the StudyMyHealth.com website.
If you want to keep the current measurement hit on “Save”.
For “experts”: By hitting the “show details” field the single trial results are displayed in a chart.
Note:
- If the error rate is too high, the measurement will be interrupted. Please start a new recording session in this case.
Interpretation of the Charts and Results
What are the calculated values?
- Mean reaction time: average value in Milliseconds of the times it took you to hit on the screen after the computer displayed the symbol. The faster you are, the better your alertness is. Values below 200ms are very rare. The One of Four test requires much longer times to react, because you have to make a decision before pressing.
- Error rate: your error rate in percent of all trials. The error is only displayed for the One of Four test. For example, if you pressed 5 false symbols out of 25 trials, the error rate is 20%.
- Average best 10%: the average reaction time in Milliseconds of the best 10% of all reaction times.
Color Bars
The graphs are showing your previous recordings color coded: green is marking your personal “normal” range, i.e. the range most of your previous measurements were in, whereas grey colors displays rather rare values (you might say “the less green the less values”).
You can switch between the result views by sliding horizontally.
Line charts
The line charts display the values of your measurements over time. The time range is chosen by the buttons below. In the line charts you can see how the values vary over time.
You can switch between the result views by sliding horizontally.
Trend charts
The trend chart is a smoothed version of the line chart. It is particularly useful to see if the values show a trend, i.e. if the get continously higher or lower. The trend chart is not shown if the chosen time range is displaying less than 5 days (note that, in this case, it does not make that much sense to look at a “trend”).
You can switch between the result views by sliding horizontally.
Single Trials
You can also look at the single trials of a measurement by selecting the measurement in the Calendar view (see below). The chart displays each trial as a blue square, Y axis is reaction time in milli seconds. Failed trials are displayed as red squares at the bottom.
Data management: The Calendar
Using the calendar you can manage the data on your iPhone or iPod, and display or delete single recordings. Days with recordings are marked with a dot. If you chose a day, the recordings you made that days are listed in the table below the calendar. To delete a single recording press on the recording. The single trial view is shown. By pressing the delete button in the upper right corner this data set will be deleted.
Export Data to iCloud Drive
Be part of a scientific world, and study your results! If you are using iCloud and have the iCloud Drive enabled on your device you can upload all results as ASCII File to your iCloud Drive. The files are stored in a folder called “StudyMyPerformance”; single session files are named after their creation date and time, and contain 2 columns. The first col is the reaction time in seconds, the second indicates whether there has been an error (value 0) or not (value 1), where applicable. Values are separated by a semicolon.
The second file is called “All_Results.txt” and contains a table with all measurement results; also separated by semicolon. The first row contains the column headers.
You can import the text files to other programs, for example Microsoft(R) Excel(R), to analyze or visualize them.
Note: in earlier versions of the App we provided services based on a custom web App; this has been closed in August 2015. However, your local datastore is not affected by it, you can always export all recordings to iCloud as described above.