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Car instrument

01 Mission

01 The mission

Car instrument panels give drivers feedback about the status of their vehicle. Some vehicle manufacturers were introducing instrument panels that were constantly illuminated, whereas conventionally, instrument panels stayed unlit until the driver switched the headlights on.


A UK road safety charity wanted to clear evidence about whether this new design could inadvertently lead to drivers failing to switch their headlights on at night, and negatively impact road safety.


This project aimed to investigate whether this new design affected the likelihood of drivers failing to switch on their headlights in hours of darkness (which is a Highway Code requirement).


Project Manager and Lead Researcher, working with a team of researchers and a technical reviewer.

  • Production of the proposal to the client

  • Production of the study plan and experimental protocol

  • Organising data collection and collecting data as a researcher

  • Carrying out the data analysis and drafting the final report

  • Leading client meetings, presenting the data at a meeting between the client and vehicle manufacturer

  • Presenting the work at the Human Factors and Ergonomics Society Europe Chapter Conference

02 Game plan

02 The game plan

We conducted this piece of research after the new design (continuous illumination of instrument panels) was launched, so we were doing evaluative research. We needed to compare this design to conventional designs and, if users made more errors in one than the other, we needed to understand how big the difference was. Quantifying the problem would help us to persuade senior managers to spend money to abandon or rectify the design.

Independent samples experiment to compare participants’ headlamp activation behaviour between:

  1. one car with continuously illuminated instrument panel

  2. one car in which the instrument panel illuminates when the driver activates the headlights​

  • 'Blind' experiment under the guise of 'first impressions of new vehicles'

  • Designed the protocol so that we would not prompt the driver to switch on the headlights

  • Designed the protocol to ensure dark adaptation of the eye

  • Matched conditions (vehicles) as far as possible

  • Recruited 390+ drivers to broadly match the age and gender profile of drivers in the UK

  • Measured location of headlight activation, timing of headlight activation, distance travelled without headlights activated, etc. to paint a clear picture.​

  • Quantitative analysis: descriptive statistics and hypothesis testing

Post-experiment questionnaire to gather attitudinal data about the instrument panels or headlights

  • Included a rating of the instrument panel, among other features of the vehicle 

  • Included an open question to collect participants' comments about the vehicle

  • Mainly qualitative analysis: grounded theory approach ​​

Researcher workshop to interpret the findings and come up with recommendations.

Preparation of presentations, a conference paper and a research report to disseminate the work to different target audiences.

  • Document and disseminate the results

  • Convince stakeholders that switching on headlights is not an error-free task and that the roll-out of automatic headlights should be accelerated

03 Results

03 The results


Participants drove on a private road system at night.

Headlight activation was not error-free in either of the cars. About 15% of drivers failed to activate their headlights before moving off in the vehicle with a conventional panel

  • The continuously illuminated instrument panel was associated with:

    • a higher rate of failure to switch on headlights before moving off and

    • a higher rate of driving out of the streetlight zone and into complete darkness without activating the headlights

  • These differences between the two vehicles were statistically significant


Yes, they did.

  • Continuous illumination of the instrument panel may enhance clarity and readability

  • Some participants stated, unprompted, that the continuously illuminated panel confused them by making them think the headlights were on 

"I thought that the lights were on because the instrument panel was lit up so brightly. When I moved off, I realised the lights were not on and couldn't easily understand the controls."

04 Meaning

04 The meaning


  • People do not reliably switch their vehicle headlights on at night, even in conventional cars

  • This error rate is higher than expected​

  • Continuously illuminated instrument significantly increase the error rate 

  • But they can be clearer to read than conventional panels


Image by Eugene Triguba


  • EC legislation to mandate daytime running lights on cars should be supported

  • Manufacturers should accelerate the roll-out of automatic headlights

  • Vehicles with continuously illuminated instrument panels but without automatic headlights should have a salient warning that activates in low ambient light

05 The outputs

Cover of conference book which includes the paper.


  • Executive presentation to brief client

  • Slide pack the client could use to present to the vehicle manufacturer

  • Technical report to support client case to vehicle manufacturer

  • Conference paper and presentation to a scientific audience - published in Human Factors - A system view of human technology and organisation



While the reporting to the client and conference went well, accepting the results could have been problematic for the manufacturer. However automatic headlamps were soon rolled out in many new cars.

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05 Outputs
06 Reflections

06 Reflections


  • The main challenge was observing and surveying drivers about the instrument panel and headlight activation without influencing the results of the study. This study taught me about careful hypothesis development, experimental design and research ethics.

  • Large quantitative data collection effort, which helped me to develop confidence in experimental design and carrying out statistical analysis to test hypotheses.

  • Learned organisational skills and simple tools such as checklists, automatic reminders and daily stand-up meetings to stay on task and keep the team delivering smoothly.

  • Demonstrated the importance of measuring many aspects of task performance to be able to tell a persuasive story: ie not just measuring whether the lights were switched on, but also where they were switched on, how long and how far the vehicles travelled.

  • Developed strong client relationship and achieved repeat business form them.


Our client did not want us to involve the vehicle manufacturers in this research. In subsequent projects I have always tried to involve the people who are expected to act on or are impacted by my work. In this instance our inability to do so held us back as we were unable to:

  • secure their buy-in and move some of the tension out of the discussion of the results

  • secure an identical vehicle without a continuously illuminated instrument panel, which would have been a better matched control.

At the time it was relatively unusual to film participants and we were concerned about distracting them. However video footage of some of the drives would have been powerful.

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