PerceptNote Puts Banknote Designs to the Test

Design testing is not easy but is good practice. Ernesto Gonzalez Candela of Mexican firm UnderCurrency, which offers consulting services and products to assess and improve the performance of banknotes and coins, presented a new tool at the Optical and Digital Document Security conference in April to help central banks optimise their banknote designs and have confidence that they will perform in circulation.

PerceptNote™ adapts the logic of rapid iteration testing, widely used in software development, and applies it to banknotes. While focus groups are useful, they are complex to design and set up, time-consuming, expensive and mean sensitive designs are shared with people from outside of the central bank.

In the world of software, it is possible to show a small group of users a different version of software than is being shown, or used, by other users. This allows continuous real-time testing of subjective questions about design with answers based on data-driven social sciences. This is not possible with banknotes, of course, but PerceptNote achieves a similar outcome using software analysis.

PerceptNote simulates conditions in payment transactions taking into account the ability of humans to perceive colour, denominations and security features. This allows first feedback on design concepts and allows designs to be compared with other banknotes.

Technology capability

The software allows the identification of areas on a note which users pay attention to. How people look at a note in different lighting conditions and at different distances, visual impairment, the impact of note wear in circulation and how different denominations will interact with each other can also be assessed.

Attention zones: ‘bottom-up’ attention is what people notice when they look at a note. Elements such as colour contrast, orientation contrast, movement, text, faces, human bodies, animals etc. These elements are the least dependent on culture and are largely intuitive.

‘Top-down’ attention is where the designer guides people to look. This is a cognitive process even when people are not explicitly aware of how they are being guided.

The software creates an attention zone map with a bottom-up and top-down score. This is useful for other assessment processes.

Impairment levels: the designer wants to know how the design will function when there is a lack of light, when the note is viewed from different distances, when the note has become worn and there has been ink wear and if there is sight impairment.

Contrast analysis plots contrast against impairment levels and shows the total contrast in the note as a function of the impairment level. This is used to see how the contrast performs as conditions worsen, the level of wear increases and impairment increases. A contrast index for different parts of the note is created.

Colour: a colour definition score is created showing a weighted average colour for the attention zones. Given how important colour is, the goal is to put distinctive colours into the attention zones to give the note a strong identity.

The resulting colour map also allows designers to understand the colour contrast of different denominations.

Confusion diagram: as part of assessing whether the design of denominations is likely to confuse the public, the software enables an evaluation of how similar design structures are between notes. Again, the main interest is the attention zones.

Functionality index: it is important that the public can establish the denomination and the authenticity of a note quickly and easily. A security and an identity mask are created for the attention zones, which is used to create a functionality score for every security feature and the identify features on the note.

Colour blindness analysis: there are different types and levels of visual impairment. The software is designed to show the attention zone map, impairment zones, colour analysis etc. for each of these, so that the performance of the design can be assessed for people with impaired vision.

Usefulness to PerceptNote

If designers use PerceptNote on their designs, they have the ability to obtain a good understanding about how the public will interact with the note both when it is new and as it wears in circulation. It will give a good indication about whether it will work for the visually impaired and if it will clash with other denominations.

It will also allow ‘early failure’ and the exploration of a wider range of design options, which is harder to do with the traditional focus group approach.

Enhancements to make the software even more capable are in development, with the assessment of optically variable device effects, haptic designs (tactility) and perception indicators being developed.

The use of analytical software in banknote design is overdue and this looks like a useful option for central banks and banknote designers to consider.