Your question may sound simple on the surface, but in practice, as I?m
sure you already know, the design of visual information display,
whether signs, or instrument panels or any other means of visually
conveying information, is an exceedingly complex field, and there are
no easy answers to the problem. Without knowing your exact application
for the information you?re requesting, I?ll try to provide as broad an
overview of available information as I can, with a search strategy
that will let you locate more on your own as need be. I?m not sure
how technical you wanted to get, but since you mentioned a particular
interest in the science behind the method, I?m including links to some
very indepth and technical scientific research.
Yes, as you?ve discovered, white on black, or black on white, is often
the standard color selection for signs of various kinds that will be
viewed under low light conditions, particularly, as you noted, when
clarity is critical, such as in aircraft instrument panels. However,
although you?ve read the studies on vision and say you aren?t
interested in the physiology, it is nevertheless important to
understand that physiology, as it is there where you must begin in
order to understand the design parameters for low light signage or
instrumentation. The white on black combination is based on this
understanding of the physiology of human vision in both its color
selection and the highest possible contrast.
Since you?ve already read the information on physiology of the eye,I?
ll just summarize here that the human eye perceives objects in
daylight and brightly lit conditions using the ?cones? of the eye,
while in dim light the eye switches to the ?rods? to see. These
different structures work differently, and therein lies the science of
seeing, on which any design of signs, especially for use in low light
conditions must be based.
When you view objects in daylight, or well-lighted conditions, you are
viewing with the cones of your eyes, and you are able to see a wide
spectrum of colors, as well as nuances of shades, patterns and
textures. In low light conditions, however, you rather see with the
rods of the eyes, which cannot distinguish color, nor much of pattern
or texture. In fact, one cannot even see straight-on with the rods,
but one must actually look a bit to the side of an object in order to
see it. Look at it straight on, and it will virtually disappear.
In addition, for the rods to be most useful, the eye must be fully
adapted to the dark, a process which takes about a half-hour. Before
that time, and also after if the eye should be exposed to bright white
light for however brief an interval, the sight is somewhere between
full use of cones or rods, and therefore not fully adapted to either.
Obviously, this makes viewing in partially lighted conditions the most
challenging of all.
These principles are the science behind the development of signs that
can be viewed in low light, or in both full and low light. Such signs
will have the highest contrast possible, and since the rods of the eye
do not distinguish color, this usually translates to a black and white
scheme. Other schemes implement a slightly lesser degree of contrast
in order to make use of the psychology of color, but still retain
enough to render the signs useful in all light conditions, including
Just to refresh your memory on these pertinent principles of vision,
here are a few sites with excellent and fairly simple explanations:
?The Joy of Visual Perception:? http://www.yorku.ca/eye/toc-sub.htm
?Vision:? http://www.darksky.org/links/vision.html (excellent site)
Here?s a study that explain matters in a little more technical detail
in case you might be interested in that:
All right, you asked for examples of research work that has
implications for design of signs to be used in low light conditions,
and there are many reports of such research with the practical
deductions that can be drawn from the tabulated results. Bear in mind,
however, that many, if not most studies are on visibility (or
legibility of signs/instruments) in general. They look at overall
factors of conspicuity, including variables such as color, size, font,
etc. with low light conditions being only one among several factors
studied. You need to look through the research to find the pertinent
sections that deal with results in low light or night conditions.
I should also mention that, not surprisingly, many of these studies
focus on transportation, probably since there are significant risks
for adverse effects if traffic signs and other visual displays are not
readily legible under all light conditions. However, just because a
study was done in the field of transportation, that doesn?t mean the
results cannot be useful for other applications. And there are
additional studies in other areas as well. Here then are some
examples for you (if the longer links aren't clickable within the
answer, copy and paste the full address into your browser):
RESEARCH AND STUDIES ? SIGNS
This site for the ?Visual Performance Laboratory? at University of
South Dakota contains links to technical reports describing work and
research performed there. Reports include ? Nighttime conspicuity of
highway signs as a function of sign brightness, background complexity
and age of observer;? and ?Optimizing the legibility of symbol highway
signs,? with links to more:
Here?s a link to a Texas DOT-sponsored study through Texas A&M
University on evaluation of fluorescent orange signs. It reports
results for both daytime and nighttime with interesting results. You
might be especially interested in Chapter 4 on color recognition.
This study from University of Iowa is entitled ?Legibility Threshold
Contrast of Uppercase Text as Seen Against a Dark Background:?
University of Ohio ? ?Unlighted Overhead Guide Sign Feasibility Study?
(Since I had trouble opening the study, this link is to Google?s
cached version of it ? you might try clicking on the link to the live
version in case it was just down for some reason when I tried it.):
Also University of Ohio ? ?Nighttime Expert Panel Evaluation of
Unlighted Overhead Guide Signs,? related to the previous, but with
emphasis on nighttime:
Another cached copy, this article by Barbara Hale, ?Transportation
Engineers Helping to Improve Road Sign Readability,? reports on
studies done at Penn State on the legibility of a new typeface for
signs. Their results include much information on its effectiveness at
From the Texas Transportation Institute is this 2001 study entitled ?
Legibility of Retroreflective Signing Material,? which includes both
day and night evaluations of materials as well as color recognition:
this PDF file requires you to have Adobe Acrobat Reader in order to
view it. If you don?t already have it, you can download it here:
This site, http://www.fhwa.dot.gov/tfhrc/safety/pubs/older/rs/rs_2.htm
, refers to a 1990 study addressing, among other issues, nighttime
legibility requirements of highway signs.
Here is a report of a study done by the Florida DOT on elder roadway
use, and includes both daytime and nighttime evaluation of font styles
and sizes for street signs and roadway signs, as well as pavement
markings. It may be especially interesting as it is well known that
one of the factors in aging and vision is the loss of the ability to
see clearly in low light conditions.
Another study on sign visibility for older drivers, including
nighttime evaluations, this one on ?Improvements in Symbol Sign Design?
by U.S. DOT Federal Highway Administration:
From Virginia PolyTech Journal of Design Communication, ?The Effect of
Color Contrast on Message Legibility:?
RESEARCH AND STUDIES ? INSTRUMENT PANELS
Ok, as to instrument panels and control panels, research and studies
for what you ask are just not readily available. That is, nearly every
study I could find on instrumentation under low light conditions talks
about some sort of illumination, i.e. LCDs, backlighting, exterior
lights, etc. Furthermore, the guidelines given below for instrument
face and panel design reference other, more standard studies on vision
and visual perception rather than studies targeted specifically to
seeing instruments. Therefore, I think you will have to review the
information on signs in general, and infer from them various color
combinations, fonts, etc. which might be applied to your needs.
Since your original question was for a book on how to design signs for
use in low light conditions, you might want to take note of the
various texts referenced in the above studies. Also, there are
guidelines and manuals online that you may wish to check out, as well
as design manuals and standards available for purchase. But do keep in
mind that, as in the case of the studies cited above, such guidelines
also generally mention low light as only one factor among several that
influence design parameters, and you may have to do some indepth
reading to find specific citations on the impact of designing for low
Perhaps not surprisingly, sign companies are a ready resource for
design guidelines for signage of various types, and are based on
principles deduced from the above and similar studies, as well as on
survey and anecdotal deductions. Here are links to several sites that
have tips and tutorials for customers on good sign design. Though I
couldn?t locate any manuals or texts specifically dedicated to sign or
panel design in low light, many/most of these guidelines speak to the
issue of visibility of in low light conditions, and give a lot of
technical guidance in terms of size of lettering, font selection,
colors, and materials among other factors.
DESIGN GUIDELINES ? SIGNS
Flynn Signs & Graphics, Inc. ? Sign Design Tips:
Electromark ? Helpful Hints:
?American National Standards Institute (ANSI) Z535 Sign and Tag
Standards? ? They state,?These new ANSI standards represent the first
significant re-write of the sign design standards since they were
initiated [in 1914]. Of special importance in the new standards are
the Appendices for each standard. The Appendix to each standard shows
sign formats, suggested writing styles, type fonts, etc.? Included are
clickable excerpts from the standards.
?Consider Viewing Angle and Light Level:
?Seven Secrets of Highly Effective Signs:?
The next most useful resource for information on sign design and
visibility in all light conditions are various governmental agencies
and departments, including OSHA, USDOT, various state DOTs, and the
FERC (Federal Energy Regulatory Commission). Here are several
comprehensive manuals on sign design that take visibility in low light
conditions into great account:
The official manual for traffic signs in the United States is the
MUTCD (Manual on Uniform Traffic Control Devices), and is the standard
to which most other manuals and guidelines refer. You can find it
The 2003 Edition is here: http://mutcd.fhwa.dot.gov/kno-2003.htm
Part 2 is the section pertaining to signs. The government does not
have a printed version of this manual, but the site provides links to
organizations that have printed it and offer a hard copy for sale.
The U.S. Army Corps of Engineers is in the process of digitizing its
Sign Standards Manual and plans to make it available on the internet,
although it is not yet complete. You can, however, currently download
the first chapter in PDF format, here: http://www.mvp.usace.army.mil/
FERC: ?Safety Signage at Hydropower Projects:? (Be sure to take
advantage of the clickable appendix links, which often have detailed
explication of various visibility guidelines.)
Washington State DOT ? Traffic Sign Design Manual:
OSHA requirements for traffic and road signs (very detailed with many
While not specifically about signs, this book for sale on ?Designing
Exhibits That Sell? has some chapters about use of graphics, color and
visual impressions that may be useful to you:
DESIGN GUIDELINES ? INSTRUMENT PANELS (INSTRUMENT FACES)
Contained within the FAA?s ?Human Factors Design Standard? are
standards for instruments and instrument panels that may be of use to
you. You can download the handbook for free, but they?ll ask you to
register. Also, the download is close to 10 Mb in size, so be sure
you have room for it. Here?s the link:
The handbook, however, references MIL-STD (Military Standards), in
particular MIL-STD-1472, which is the ?Design Criteria Standard ?
Human Engineering.? This is also available as a download, although it
is for sale and not for free. Find it here: http://www.mil-std-1472.
com/ A complete list of standards available for sale is here: http://
www.docudemand.com/ In addition, the FAA references several other
The Nuclear Regulatory Commission (NRC) Human-System Interface Design
Review Guidelines: NRC: Human-System Interface Design Review
The Electric Power Research Institute (EPRI) Department of Energy
Standard ?Guide to Good Practices for Equipment and Piping Labeling:?
The Federal Highway Administration has published a set of Human Factor
Design Guidelines, here:
includes design guidelines on ?Selection of Colors for Visual Displays,
well as other information you may find useful. Of particular interest
is the fact that they cite specific rationales for the selections
This technical report from the University of Michigan?s Transportation
Research Institute, entitled ?Suggested Human Factors Design
Guidelines for Driver Information Systems? addresses visual displays,
and discusses such variables as color, font selection, type size,
glare and lighting:
The ?Driver Interface Group? homepage is here:
General Guidelines for Advanced Traveler Information System (ATIS)
Displays (includes supporting rationale):
This report from the Federal Railroad Administration (FRA) is on
design guidelines for locomotive cabs, and addresses such issues as
workstation design, including instrumentation layout and visibility,
controls, labeling, and others in all visibility conditions:
The report above refers to ANSI standards ANSI/HSF-100 1988, which can
be purchased here: http://www.hfes.org/Publications/ANSI-HFS-100.
This article: http://www.tifaq.com/archive/ansi-standards.txt
above with regard to its usefulness in actually designing a work
terminal, and concludes that other standards and guidelines might
actually be more useful. In particular it references ISO 9241, the
European Community international standard. That can be purchased here:
Here?s a terrific list of resources from ?The Visual Expert?
pertaining to vision and human factors in design:
Here is a list of references on human factors in design, including
some to signs and equipment/instrument markings:
And from the International Organization for Standardization (ISO) is
this list of design standards for signs of various types:
Color Resources ? a page of links to a lot of information on various
uses of color: http://donporter.net/NewSchool/Color/
International Ergonomics Association: http://www.iea.cc/
American National Standards Institute (ANSI): http://www.ansi.org
American Society for Testing and Materials(ASTM): http://www.astm.org
Society for Information Display: http://www.sid.org/
United States Sign Council: http://www.ussc.org/advantages.html
You also mentioned wanting a reference book. Some of the sites listed
above refer to various texts and books. Also, in the case of the
standards publications, those must be purchased and the sites provide
links for doing so. In addition, here are a few other books that may
interest you. Again, remember that in sign design, low light is
considered one of many factors that influence selection of size, color,
contrast, type, etc.
Sign Design Guide: http://www.signdesignsociety.co.uk/book.html
Designing Signs - Corporate Signs:
Sign Easy Type Guide: http://www.amazon.com/exec/obidos/ISBN%
I hope this information and these links will be helpful in providing
you with direction to the kind of guidance you?re looking for on sign
and instrumentation design for use in low light conditions. If
anything isn?t clear, please do use the ?Request Clarification?
feature to ask, before rating and closing the question. I will be
happy to work with you further if necessary to ensure you have the
information you need.
Search strategy: I began by using terms such as signs and ?low light?
or night without much success. After a great deal of trial and error,
the following terms ultimately proved to be the most useful:
"low light" rules OR standards OR manual OR guidelines
signs standards specifications
sign nighttime legibility study OR studies OR research OR evaluation
legibility research study "instrument console" OR "instrument faces"
OR dials OR
legibility ergonomics "low light" OR dark OR "poor light" OR night OR
?designing an instrument panel?
research "low light" "instrument faces" OR "instrument clusters" OR
In addition, when reading through the results, I looked for additional
references that I could use for further searching, such as standards
documents, organizations and other terms, including ?gauge faces? and
ergonomics, ?human factors? and ?ergonomic design.?