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I am a designer just preparing an app for the "in car" area.

Normally we have a bunch of colors to use and we usually use dark colors on a light background. Now our client came up with some question about eye-blinding displays in cars. A little research shows that most apps designed to use in cars while driving have a dark background with light colors for typography.

Is that just a common behavior, that a dark screen will be better to use while driving, or is it based on some studies that most car drivers feel more comfortable with a dark background on screen?

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    I'm sure there are usability implications, but it is my gut feeling that this is more to do with safety. From a safety perspective, a brightly-lit screen could be a distraction when driving at night-time on unlit roads (when you pupils are dilated). Also, there are generally traffic rules which state that only red lights may be displayed to the rear of the vehicle.
    – Brendon
    Jun 28, 2013 at 10:39
  • Also, many smartphones already come with an auto-brightness detector that dulls the screen when there is less light out there (i.e. at night). It might also be worth finding out if there is any published reasoning as to why this occurs as that should help you get some useful information on this.
    – JonW
    Jun 28, 2013 at 10:55
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    Better quality navigation devices even have nightcolor schemes for this reason. This isn´t just distraction, it is night adaptation. Your pupils would contract from brightly lit screens.
    – MSalters
    Jun 28, 2013 at 12:37

4 Answers 4

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I would say it has to do with the following reasons :

However, if you are using a display in a dark environment, it’s better to use a dark background as it lets you keep your eyes dark adapted. That’s why controls for airplanes and GPS units for cars switch to a dark background at night. Usually, however, the results don’t look like symbols and text floating in the darkness of space…there’s still a sense of there being a dark surface to ground the view. So the concerns above are somewhat mitigated.

  • Distractions of bright interfaces : One of the main concerns with bright interfaces is that they can be really bright and a significant distraction and prevent users from focusing on multiple things. Referring from the same article referenced before

Modern displays are now bright enough that they can be uncomfortably bright. But that effect will be seen in a dark room, not in daylight. Our visual system overall adapts (adjusts its sensitivity) to the ambient brightness by several orders of magnitude. That’s how we see in a dim room and in full sunlight, and that adjustment is the reason you are momentarily blind when you walk into a dark theater after being out of doors, or painfully squint on the way out. If your display is bright enough to be significantly brighter than anything else around it, then you’ll find it uncomfortable. But we cover this by saying you should use a dark background when in the dark. And turning down the brightness remains an option for leaving the background white.

I also recommend listening to this excellent talk Trip O'Dell: If UX Can Kill it Probably Will - Designing for the 70 MPH Interface as it gives excellent inputs on how to design for car based interfaces and what you should consider.

I also recommend looking at this PDF document"User Experience design for Vehicles" for inputs on how to design applications for automobiles

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    Bear in mind that close eyesight for tiny writing (particularly in poor lighting conditions) starts to fail beyond the age of 45: and switching to your reading glasses is rather a dangerous thing to do at 70mph...
    – PhillipW
    Jun 28, 2013 at 13:23
  • Your first link "black or dark backgrounds provide the easiest contrast" draws a different conclusion. From the article at the link: "That’s why a better choice for displaying paragraph text is black text on a light background with a tint of gray."
    – mawcsco
    Jul 1, 2013 at 14:12
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As others have mentioned, this is very much a safety issue and very much worth asking!

Fortunately, user experience in vehicles has a long history of study and standardization. SAE International, formerly the Society of Automotive Engineers, has published a number of standards and papers related to this issue. Here are some that may be relevant:

http://standards.sae.org/j2831_201204/ Development of Design and Engineering Recommendations for In-Vehicle Alphanumeric Messages.

This Information Report provides recommendations for alphanumeric messages that are supplied to the vehicle by external (e.g., infotainment system) sources while the vehicle is in-motion. Information/design recommendations contained in this report apply to OEM (embedded) and aftermarket systems.

Ergonomic issues with regard to display characteristics (e.g., viewing angle, brightness, contrast, font design, etc.) should review ISO 15008

http://standards.sae.org/j2217_199110/ Photometric Guidelines for Instrument Panel Displays That Accommodate Older Drivers.

Physical parameters that influence the legibility of an instrument panel display include letter/graphic size, the luminance and color difference between graphics and background, the observer's luminance adaptation level, and the level of glare present. Several aspects of visual functioning deteriorate as part of the normal aging process. These include a reduction in luminance and color contrast sensitivity, an increase in sensitivity to glare, a reduction in visual accommodation capacity, and a reduction in the sensitivity to light. This SAE information Report provides introductory information that should be considered when setting photometric guidelines for instrument panel displays that are designed to accommodate the older driver

http://standards.sae.org/arp4032b/ Human Engineering Considerations in the Application of Color to Electronic Aircraft Displays.

This document is intended for the application of color to cathode-ray-tube (CRT) displays, liquid crystal displays (LCD) and other types of display technologies such as projection displays. Emerging color display technologies other than those noted above, may not be adequately covered by these recommendations.

Color recommendations will not address Night Vision Devices (NVD), Head-Up Displays (HUD) or Head or Helmet Mounted Displays (HMD).

This document is applicabel to aircraft as understood in 14 CFR Parts 23, Part 27 and Part 29, and EASA CS-23, CS-25, CS-27 and CS-29 certification standards

Others that may be of interest:

http://standards.sae.org/j2365_200205/ Calculation of the Time to Complete In-Vehicle Navigation and Route Guidance Tasks.

This SAE Recommended Practice applies to both Original Equipment Manufacturer (OEM) and aftermarket route-guidance and navigation system functions for passenger vehicles. This recommended practice provides a method for calculating the time required to complete navigation system-related tasks. These estimates may be used as an aid to assess the safety and usability of alternative navigation and route guidance system interfaces to assist in their design. This document does not consider voice-activated controls, voice output from the navigation system, communication between the driver and others, or passenger operation.

http://standards.sae.org/j1663_199508/ Truth-In-Labeling Standard for Navigation Map Databases.

This SAE Standard is a truth-in-labeling standard for map databases.

http://standards.sae.org/arp4102/ Flight Deck Panels, Controls, and Displays.

This document recommends criteria for the design, installation and operation of panels, controls, and displays on the flight deck of transport aircraft.

http://standards.sae.org/arp4102/7/ Electronic Displays.

This document recommends criteria for electronic displays on the flight deck of transport aircraft. Electronic displays include electronic flight instruments, alert displays, aircraft system displays and control/display units for flight management and radio management systems.

I would also echo what @Severan Rye discussed with regard to avoiding the blue end of the spectrum in night displays.

Descriptions are from http://webstore.ansi.org

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  • Thank you for the links Steven. Can you please summarize the key points of the links in your answer so people don't have to navigate to all the links?
    – rk.
    Jun 30, 2013 at 3:43
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    The SAE site doesn't provide the greatest summaries, but I found better ones at http:webstore.ansi.org, which I'm adding above. The standards themselves are licensed by SAE, not free, so not available to copy here. Jun 30, 2013 at 4:45
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There are usability implications involved, mostly with the human eye, sensitivity and the environment the car is in. There are no rules per-se, we relied on gut feelings, actual experience and votes from our testers.

Lets start off with the Purkinje Effect

the tendency for the peak luminance sensitivity of the human eye to shift toward the blue end of the color spectrum at low illumination levels.

This Wikipedia article gives you the in-depth details to help you design better experiences, I'm going to brief on the take-away points I used in my research & presentation for a specific high profile client.

  • You can drive a car and use the app, during daytime, night time, inside tunnels, in brightly lit environments, etc. thus making the lighting inside the car change.
  • The fundamental requirement for our app is to be readable all times and not blind the user or irritate them in anyway, thus the photopic vision of the user was our key.

In the end - We designed & built 2 different skins for the app. In dark environments, switch to Black and Gold and while bright sit pretty in gold and black. (we had very little freedom on the color palette).

The skin control was linked to a light meter and the switch happens in 2 ways - We had a default switching configuration set and we let the user select / adjust and remember a setting for the display based on the lighting in the car & its environment.

Bottom line: Don't let your design be the cause of an accident.

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  • Also, if you are designing for a specific car then take note of the car's interiors i.e. colors used in places where light bounces, where your app would be placed inside the car, and window shades. Designing for a specific car also puts you at an advantage - since it will have a targeted audience, study them.
    – Rayraegah
    Jun 28, 2013 at 13:46
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For screens in a car, there are multiple considerations you need to take into account including:

  • Driving during the night

    • If the total brightness of the screen (integral of all pixels + leakage from sides) is very high, it will illuminate the car, causing the windscreen to act like a mirror.
    • If the screen has very areas, the eyes' irises will contract, preventing the eye from picking up details from dark areas (e.g. the road).
  • Driving during the day

    • In very bright environments, light on dark will help you see the text but make it hard to differ between shades (white text vs grey text). Dark on light will help you see the difference between shades, but if the environment is too bright, you will only see the darker text (the grey text will seem white).
  • Attracting attention only when needed

    • If the background is dark and the foreground is bright, you can vary the brightness and color of the symbols/text on the screen to attention only to the critical issues e.g. brake failure in bright red, over speed limit in a bright white/color vs. A/C temperature in a grey, so that it won't attract too much attention. Don't make the defaults too bright, so that the screen won't draw attention unless necessary.
    • If the entire background is bright (with dark foreground), then the entire screen will draw attention, something which may be dangerous while driving.

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