Whenever a new interface or warning for the driver is implemented, it needs to be ensured that the driver can still keep attention on road. The new interface / warning (further on just called new design) will be tested in a driving simulator at some point. The driver will drive the vehicle and conduct a task with the new interface or react to the warning, in parallel they will also conduct a secondary task to challenge the driver. In extensive research a range of suitable secondary tasks can be found in literature. I implemented one of them in JavaScript and added a tactile version. Before I describe the tasks in detail I would like like to explain more of the underlying thoughts to have such tasks and their exact purpose.

Background

Every task we do (reading, cycling, cooking, etc.) requires mental energy. The task of driving is no exception, it involves mainly cognitive, and visual resources. New designs are required to be created in a way that enables the driver to remain focused (visually and cognitive) on road for a save drive or for a warning to capture the driver’s attention.

Particularly accident prone driving situations are sudden changes in the environment to which the driver needs to react timely, e.g., a child runs on the street or the truck driving in front looses part of its loading. Such scenarios would be excellent to test new designs and ensure the safety of their use. Following, the evaluation of new designs could be conducted in a challenging driving task to simulate the performance of the new design in a mentally challenging situation. However, driving is a skill and its perceived difficulty varies a lot from one person to another. It would be challenging to find people with a comparable level of driving skill to make the study comparable. So instead of a difficult driving scenario we conduct the study in an easy driving scenario and add a secondary task to make it challenging.

Requirements for secondary tasks while driving to add workload

Each participant will conduct exactly the same secondary task with the same settings. A secondary task conducted while driving needs to add the same amount of mental energy over the period of the study in order to make the trials with different participants comparable. It needs to be something continuous, repetitive, but not too challenging so the driver can still remain focused on road in parallel. Additionally the option to implement such a task in different modalities maybe favourable, at least it was for me and my research about haptic warnings.

Examples of secondary tasks

The examples of the following tasks could be used as secondary tasks, from literature:

• PDT: LED signals appear on the windscreen at random positions in the driver’s normal field of sight. They appear within three to six seconds and have a duration of one second. When an LED signal appears the driver needs to respond, by clicking on a button on the index finger, within 200 ms to 2 s after onset, otherwise it is a miss. Drivers should detect as many signals as possible without decreasing their driving performance (driving has first priority). (Jahn et al., 2005; Martens and Van Winsum, 2001)

• N-back: A set of ten numbers (between zero and nine) are played to the participant sequential. After each number it should be responded either nothing or the number which was played n numbers back. “n” can be between zero and two, dependent on the difficulty level.

  For each level of difficulty four sets of each ten numbers were played to the participant in the timeframe of two minutes. Between each of the four sets there was a short break and the keyword “next” marked the start of the next set of numbers. Each number was presented in the timeframe of 2.25s. A break of 30s is recommended between the end of the initial reference period (single task driving) and start of instructions, so that the participants can prepare themselves for the test (Mehler et al., 2011 – see paper for detailed instructions)

• Rapid Serial Auditory Presentation (RSAP): A stream of random letters is presented verbally. Randomly, numbers are spoken instead of a letter. The participant needs to react only to a number by tapping on the display or pressing a button. The task exists also in a visual version (RSVP). (Soto-Faraco and Spence, 2002)

Implementation of the RSAP, RSVP and RSTP tasks

I implemented the RSAP and RSVP tasks in JavaScript, HTML, and the NodeJs framework. Further I added a tactile version. You find the tasks for download on Github: https://github.com/cognitiveresources/Detection-Tasks

The visual and the auditory task present a series of rapidly changing numbers and letters. In literature those tasks are called Rapid Serial Visual Presentation (RSVP) and Rapid Serial Auditory Presentation (RSAP) tasks. Each letter or number appears for a predefined timeframe. After exceeding this timeframe, it disappears and a blank screen is presented for a predefined timeframe. Thereafter, the next letter or number appears. Whenever a number is shown (target) the participant should tap on the screen or click the mouse (dependent on the device you use to present the tasks). The tactile task was designed with a similar characteristic. The JavaScript foresees to communicate with two motors controlled by an Arduino for this task. The participant holds one motor in the left and one in the right hand. During the course of the task the activity of the motors will change: only the left vibrates, only the right vibrates, both vibrate or none vibrates. Whenever both motors vibrate (target) the participant should tap on the screen or click the mouse.

To start the visual or the auditory task, open the desired html file of the task. You will see a website in which you can specify the setting for the task: duration of the task, duration of a cue (letter / digit) is presented, duration of a blank screen, number of targets (numbers) and number of letters between the targets. When you click start, the next page opens showing a screen with an underscore. Now you can get the participant ready. When you press the start button the task will start after 5 seconds. For the tactile task you need to set up the hardware (Arduino and two vibrating motors (e.g. Lilypad)) and you need to install the NodeJs framework and the JohnnyFive framework for this task. In order to prepare the Arduino to communicate with the JavaScript server you might need to install StandardFirmata on the Arduino. To start the tactile task you need to start the JavaScript file first in the command line window: “node PilotTTask.js”. This will start the JavaScript server. Then, open your browser and type in the URL “localhost”. You should now see a website to define the settings for the tactile task similar to the RSVP and RSAP task.

Sources:

1. Jahn, G., Oehme, A., Krems, J., and Gelau, C. (2005). Peripheral detection as a workload measure in driving: Effects of traffic complexity and route guidance system use in a driving study. Transportation Research Part F, 8(2005), 255-275.

2. Martens, M. and Van Winsum, W. (2001). Effects of speech versus tactile driver support messages on driving behaviour and workload. TNO Human Factors. Retrieved from http://www-nrd.nhtsa.dot.gov/pdf/ESV/esv17/Proceed/00080.pdf

3. Mehler, B., Reimer, B., & Dusek, J. A. (2011). MIT AgeLab Delayed Digit Recall Task (MIT AgeLab White Paper Number 2011–3B). Retrieved from Massachusetts Institute of Technology (MIT) website: http://agelab.mit.edu/delayed-digit-recall-n-backtask )

4. Soto-Faraco, S., and Spence, C. (2002). Modality-specific auditory and visual temporal processing deficits. Quarterly Journal of Experimental Psychology: Human Experimental Psychology, 55(A), 23–40.