Test: Street name signs for Copenhagen Municipality
Through an external design agency, the City of Copenhagen has developed a new corporate typeface family as part of their updated visual identity. The typeface family also includes a version for street name signs. The municipality's design department was interested in creating the most readable street signs by identifying the optimal relationship between letter spacing and point size of the letters.

Gadenavneskilte Københavns Kommune – mest læsbare gadeskilte

Numerous research projects have found evidence that wider letter spacing optimizes the reading of words at great reading distance. At the same time, the greater the point size, the better the legibility. Large font sizes and wide letter spacing both require extra horizontal space, which is not always available especially for longer street names. We were therefore interested in investigating whether an optimal relationship between point size and spacing exists if the horizontal space on the sign is kept constant. The closest spacing was therefore set to the largest point size, while the widest spacing was set to the smallest point size. Thus, the different typographical settings of the street name got exactly the same physical length.

We tested three different spacing values. Each participant was presented with 20 signs in each of the three typographic variants. Half of the signs at each test were set up for frontal reading - the other half for an angled reading.
In order to eliminate the possible effect of subject recognising the street names, the 60 street names were existing names from a number of Danish small towns distributed throughout the country.

Mest læsbare gadeskilte
Bogstaverne optimerer læsning af ord på stor læseafstand

With the goal of eliminating the effect of the highly variable length and reading difficulty of street names, all street name signs were printed in the three different typography variants - a total of 180 signs. The subjects were divided into three groups, with each group reading different typography variations of each street name. We divided each of these three groups into two, so that one half read the first half of the signs at frontal 0° angle, and the other half read the first of the signs at 45° angle.

The measure was to identify the least possible distance from stimuli where participants were just able to read the street name. The subjects' performance provided us with sufficient data material that we could analyse and present to the client with the help of various statistical methods. In this way, the City of Copenhagen has chosen with great certainty the optimum typography setting for the future Copenhagen street name signs.

Test: Identity font Copenhagen Municipality
In connection with the Copenhagen Municipality's visual identity update, an external design agency developed a new typeface family to be used in all written communication from the municipality. The design department in the municipality needed to ensure that the typeface would be suitable for the purpose.

33 people aged 18-86 years participated in the test. We used the well-documented Radner Reading Chart – a scientifically validated vision test developed for standardized measurement of reading acuity, critical print size and reading speed.

The test is based on 28 paragraphs, which has been measured for the same difficulty, structure and number of words. To enable statistical analysis, the size of the paragraphs is reduced logarithmically. The subjects read the paragraphs starting from the largest point size and read to the smallest possible size. They were instructed to read a section of text as quickly and correctly as possible without correcting reading errors. In order to eliminate an undesirable effect of the possibly varying severity of the paragraphs, the participants were divided into three groups with typefaces and paragraphs in different pairing combinations.

Radners læsesynsprøve

We compared reading of two versions of the Regular weight of the newly developed typeface family to reading the previously used font, Gill Sans Light. The results of the experiment, which was subsequently published as a scientific paper, showed interesting reading differences among older and younger participants, and in general that the new typeface was suitable for the intended use.

Beier, S. & Oderkerk, C.A.T. (2019) ‘The effect of age and font on reading ability’, Visible Language, 53.3, 51–69.

The effect of fonts boldness on different point sizes
An experiment by Beier and Oderkerk (2019) demonstrated that at both small and large point sizes, light and ultra-black fonts were inferior to all the fonts in the middle of the weight scale. Further, the bolder weights in the middle of the scale enhanced recognition in the small font size, while failing to do so in large font size.

Font boldness – 3 sizes separated
Font boldness – 3 sizes separated

These findings provide evidence that under reading situations involving small font sizes and signs read form great reading distances, bolder weights will improve letter recognition. They also showed that both light and ultra-black font weights should be avoided in any case where letter recognition is a priority.

For more see:
Beier, S. & Oderkerk, C.A.T. (2019). ‘Smaller Visual Angles Show Greater Benefit of Letter Boldness than Larger Visual Angles’. Acta Psychologica 199 (August): 102904. 1–8.

Typography for elderly people
By testing participants of all ages, researchers have found that reading speed stabilizes around the age of 40, after which it gradually continues to decrease over the lifespan; that the point size that one can read at a relative good speed slowly decreases from the age of 23, with a rapid decline from the age of 68; and, finally, that reading acuity (clarity at small point sizes) tends to worsen from the age of 16 (Calabrese et al., 2016).

Older participants are also more affected by added ‘noise’ or blurring of the test fonts in lexical decision tasks of identifying words or non-words: they tend to retain less visual information from the peripheral visual field (which is important for reading longer paragraphs of text); they are more easily distracted by irrelevant elements in the text; and they have greater difficulty tuning into a specific font style, than younger participants. Our data further indicates that compared to younger readers, older readers are more easily distracted by the negative influence of letter crowding (letters appearing to merge with their neighbors) and lighter font weights.

In short, when designing for this reader group, keep in mind to create simple layouts, with high contrast between background and foreground, and never use light font weights, or unusual font designs.

For more see:
Beier, S. & Oderkerk, C.A.T. (2019) ‘The effect of age and font on reading ability’, Visible Language, 53.3, 51–69.

Character complexity
Research shows that the simpler the character skeleton, the more legible the character.

This rule of thumb only applies when the shape of the character does not increase the rate of misreadings. In an investigation of the legibility of digits in a short exposure of three-digit strings at the peripheral visual field, research by Beier and Bernard (2018) showed that digits and letters benefit from having the simplest shapes. In other words, the shorter the morphological skeleton, the more legible the character.

These results somewhat contradict the approach applied by several renowned type designers whose focus on ensuring differentiation between characters may result in added features, such as cross bars and tails.

Character complexity

For the London Underground typeface, for example, Edward Johnston created a loop in the lowercase ‘l’ to differentiate it from the capital ‘I’. This resulted in a more complex letter skeleton, which in theory would lower legibility.

An earlier investigation, also by Sofie Beier (Beier & Larson 2010), showed that at greater reading distances, a tail on the ‘l’ results in fewer errors, that a cross bar on the letter ‘i’ can improve legibility, and that the letter ‘a’ should have a two-storey design.

Following this, we conclude that the advantage of the shorter morphological skeleton only applies in situations where the simple character skeleton will not result in a greater number of misreadings.

For more see:
Beier, S., Bernard, J.B. & Castet, E. (2018) ‘Numeral legibility and visual complexity’, Proceedings of DRS2018, Design Research Society, vol. 5, 1841-1854, Limerick, 25th-28th June.

Beier, S. & Larson, K. (2010) ‘Design Improvements for Frequently Misrecognized Letters’, Information Design Journal, 18(2), 118-137.