Legibility of numerals

Complex skeletons lower recognition. We have shown that within well-known characters shapes, some variations are significantly easier to recognize than others.

Research paper 

Numeral legibility and visual complexity

To enhance the peripheral legibility of numerals we designed three versions of the digits from 1 through 9 by modifying the complexity of each numeral (equivalent to their digit skeleton) while controlling for variations in other physical parameters.

Observers identified the different versions of the digits in random three-digit strings, presented within their peripheral visual field. Our results showed that the digit ‘1’ should have a narrow design without a crossbar at the bottom, the digits ‘3’ and ‘9’ should benefit from open apertures, and the digit ‘7’ should have a straight leg and no serif at the horizontal bar. The data further demonstrated that crowded digits presented in the periphery of the visual field generally profit from a short morphological skeleton. The findings can improve the identifiability of numbers for readers with normal visions as well as for readers with central visual field loss.

June 2018 Sofie Beier presented a paper at the Design Research Society. The paper received “Best paper award certificate”.

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.


Presentation at ATypI 

The Legibility of Numerals

When a reader encounters an illegible letter, he or she can draw on information from the neighboring letters and from the sentence structure and thus make an educated guess about what the letter might be. The same is not the case when the target is a number. In such situations, there will be no additional help from the surrounding numbers or from the structure of the text. It is therefore essential that one number is not mistaken for another. In spite of this, there is very little relevant research on numeral legibility.

In this talk I will review existing knowledge and present the findings of a new study into the individual legibility of numerals with different skeleton structures.

The talk is available on YouTube >>