Towards the Right Direction in BiDirectional User Interfaces
Imagine a world… a world of inconsistent usage of UI elements…
Inconsistence that sometimes occurred even in products of the same vendor or even within the same product…
A world with incorrect usage of text direction…
It’s very hard to use interfaces in such a world…
But it exists. Thousand of millions users all over the world face everyday problems of misunderstanding, usage errors, and loss of time due to incorrect and inconsistent interfaces.
Those languages rely on unique BiDi writing systems, mixing the native RTL script with LTR strings - Latin script, numbers, and other notations.
Speakers of those languages are 12% of the whole world population. With Standard Arabic as the fifth most popular language in the world.
The fifth part of the content language for world websites represented by BiDi languages, with Persian as the fifth most commonly used language in April 2021.
In March 2020, Arabic was the fourth most spoken language by global internet users, with a rapidly growing internet penetration.
With the increasing number of BiDi users and products in the last three decades, BiDi design has become increasingly popular in professional HCI communities.
Leading web companies and individual professionals have been trying to define the optimal direction of UI elements in BiDi interfaces.
Both groups rely on the "Partial Mirroring" rule: mirroring just a part of left-to-right UI elements, such as layout, navigation elements, etc....
While maintaining the LTR direction for the elements not related to RTL script: numbers, graphs, etc.
Despite extensive discussions on "Bidirectional design" in the professional community, there is a lack of empirical studies on how BiDi users perceive and process UI elements' direction.
Consequently, there is little evidence to rely on for guiding BiDi design.
However, we argue that empirical evidence for BiDi design guidelines is important.
BiDi languages are different not just from LTR languages in their script directionality usage but also from each other in some rules regarding specific information representation.
Moreover, in Psychological studies was shown that BiDi speakers' direction preferences could be mediated by LTR language proficiency level, number of years of studying mathematics, and other factors.
These facts portray a picture that challenges the notion of simple, universal BiDi design formula and emphasize the need for a systematic study on this topic.
To assess the nature of inconsistent UI elements in BiDi interfaces, we reviewed the top Hebrew websites in Israel and identified several dozens of UI items that were used in both RTL and LTR versions.
Of those, we selected 32 UI items that were used frequently and, for further exploration, tentatively classified them into five categories.
For each group or specific item, we reviewed potential resources to identify the roots of direction inconsistency.
Comparing the UI items with the guidelines and the HCI literature, we concluded that the major reason for the inconsistent directionality of UI elements is the paucity of current guidelines.
No specific recommendations were observed for 20 out of the 32 inconsistent UI items.
The existence of two appropriate directions for the same information representation in Hebrew, suggests another possible explanation for the multitude of UI elements with inconsistency–
What if the direction of the element does not really matter?
These findings indicate a need to gather more evidence regarding this topic.
To answer this question and demonstrate the usefulness of empirical data for the BiDi design study, we conducted a questionnaire with Hebrew speakers.
We based on the UI items, identified in the previous step and developed 2 types of stimuli: RTL & LTR UI item versions or UI items with ambiguous content.
We found that Hebrew speakers exhibited a differential preference for the directionality of the UI elements: 13 items were preferred in their LTR version; 8 - in RTL. For the direction of 6 UI items, there were no clear preferences.
We observed that the direction preference of Hebrew speakers corresponded to the recommended direction only for 3 UI items out of 7 mentioned in the guidelines.
We did not have enough information to explain some of the findings because it was an exploratory study. These findings require further investigation.
For example, a puzzling finding is the lack of direction preference for the "departure" icon in conjunction with a significant RTL direction preference for the "arrival" icon.
You can find other open questions in our paper.
One of the study's exciting findings is that 4 out of the 5 UI items' groups described in our interfaces’ review were identified as-is in the clustering analysis in the questionnaire.
We believe that this classification can serve as a reasonable basis for future research and for BiDi design guidelines.
The described findings provide potential insights for BiDi design rules and empirical evidence for the problem's complexity.
We call the HCI community to pay more attention to the BiDi design topic and believe that joint research will help build evidence-based guidelines for BiDi design and finally improve the experience of millions of BiDi users.
Thank you for the attention! If you have questions about our work, please, feel free to contact us.