Intermediate results of the icon tests: Tango

With a series of icon tests we currently study effects on the usability of icon design. This article however does not focus on these general design effects but presents findings specific to the Tango icon set.


The introduction of the new Breeze icon set in KDE let us again wonder, what aspects of an icon set actually takes what impact on the usability of it. We investigated Oxygen and Tango Icons for the LibreOffice project before, but our focus then was on checking all icons of the standard tool bar. This time we focus on different icon sets and will use 13 common actions to compare them.

With this series we are going to test at least 10 different free icon sets: Breeze, Oxygen, Tango, Faenza, Nuvola, Nitrux, Elementary, Crystal Project, Humanity and Treepata. These icon sets differ on various aspects: use of color and details, flat or not and sometimes even on the metaphor used.

So, we generally want to analyze effects of icon design on the overall performance of an icon set. Statistics on this issue can obviously only be done after all icon sets have been tested. But with every test, we win some specific insights in strengths and weaknesses of each icon set tested.

In this post we share some findings about the Tango icon set.

The study was finished by 531 participants (drop-out rate 3%) with an average handling time of 2:08 min.

Results of Tango icons

Table 1 lists the aggregated quality indicators. They show how well all icons that we used for the test were suited to symbolize the different terms. It has a range from 1 (no fit) to 10 (perfect fit), whereas you would expect values of at least 9 for well represented terms.

Table 1: Quality of the icon set for different terms based on assignment ratio (percentage of missing assignments) and conspicuity (or speed of picking icons).
TermQuality Indicator

Table 2 shows a cross-table with the percentage of false associations. These are terms where the intended icon was not chosen by the users, but some other icon was.

Table 2: Cross-table of icons and terms with percentage of false associations. The direct match is inverted (1-value, e.g. 0.99 for Add) to obtain comparable data.



Tango gets the best results in this series so far. There is no icon that does not work well. Tango uses the standard metaphors for Copy and Paste. As we have found these metaphors to be not working well before, it is not surprising that these icons perform comparably bad. We also find the normal mix-up between Undo and Redo.

A couple of things are surprising though. First, Tango chooses a non-floppy-disc metaphor for Save. And it is working really well – but not quite as good as the floppy disc in other tests.

Also the Printer icon is working slightly worse than in other tests. When comparing the picture with those from other icon sets, the Tango printer has no paper feeder on top. Perhaps this paper feeder is an important part of our mental prototype of a printer (even though they often look different today). But it definitely makes the icon more unique.

If you know how to design icons and would like to help us to identify metaphors that work better, please contact us. Also, all raw results are publicly available on our open usability platform UserWeave.

As mentioned before: These results only reflect the internal quality of the Tango icon set. The final interpretation will be done after all sets have been tested. So stay tuned and please participate in our follow-up tests. And, of course, feel free to discuss these findings with us.

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