Interface metaphors, such as the classic desktop metaphor common in graphical user interfaces (GUIs), leverage users’ existing knowledge of a specific domain to enhance the learnability of its software. This means that users can immediately understand how to interact with elements and what possible actions there are in the UI to get what they want. Whilst metaphors may improve the user experience of an interface by allowing users to intuit how to accomplish things, these interface paradigms face challenges in a technological environment that is constantly and rapidly evolving. To overcome these challenges, the field of UX should increasingly turn their attention to interface idioms.
Many of us can recall spending school lessons learning the differences between metaphors and idioms. Linguistically, they are both phrases used to describe an object or an action to which they are literally unrelated, in order to convey shared meaning. The crucial difference is that metaphors, such as ‘To set the scene’, are intuitive in the sense that they share the same properties of the literal meaning they represent. This means that even if you’ve never heard the metaphor before, you can infer its meaning due to your mind’s ability to immediately draw connections between things. Idioms, such as ‘That’s cool’, on the other hand, do not share the same properties as what they’re referring to — what does low temperature have to do with something being acceptable, impressive, or attractive? Idioms therefore require of people to consciously learn their meaning first.
What’s the point of using figurative language to communicate when you can just say exactly and literally what you want to say? Why beat around the bush? Because often, literal meanings are complex, take time and effort to explain, and may require concrete domain knowledge of the listener to understand. Using symbols like metaphors and idioms for conveying meaning simplifies what you want to say quickly, and allows communication to take place on a more abstract level where expert knowledge isn’t required.
The same rationale applies to graphical metaphors and idioms, long considered to be the key to intuitive UI design. Completing the simplest of tasks electronically was once a domain restricted to solely technical experts, because the command-line interfaces that were prevalent at the time required the user to both know by heart the set of possible interactions with said interface, as well as the knowledge to understand the effects of their actions with the limited feedback given by the system. As GUIs were introduced, however, they wildly expanded the usage of personal computers to include nearly everyone, by simply taking this complicated and specialised domain knowledge and mapping it to what we know: namely the direct manipulation of graphical representations of physical world objects, and using this to indicate the interface’s functionality to the user. This groundbreaking evolution transformed a specialised technical domain to public usage by taking the knowledge required to use the system out of the user’s head and into the world around them. This allowed the user to understand it using our natural knowledge of things such as spatial awareness, rather than the unnatural act of memorising information. Indeed, the success of the original Apple Macintosh was by and large attributed to its desktop metaphor. This leveraged users’ existing knowledge of office layouts and conventions by using metaphorical representations of office objects, allowing users to intuitively figure out how to accomplish tasks.
A problem with this acclaim for metaphors is that the UI features often highlighted as successful metaphors aren’t actually metaphors — they’re idioms. For someone who hasn’t used a mouse, scroll bar, close boxes, or hyperlinks before, they’re not at all intuitive because they have no real-world counterparts. Similarly, if you consider the introduction of the iPad and other tablet devices, someone who has never used a multitouch device before won’t spontaneously think of performing the double-tapping to enlarge content as an obvious thing to do: we don’t double-tap paper to read better, we bring it closer. But once these idioms are learnt, and if they’re good idioms, they rarely — if ever — need to be relearnt.
So is the case for metaphors, you might point out, so why argue that idioms are better for UX design than metaphors?
There Are More Idioms To Be Invented Than There Are Metaphors To Be Discovered
Because metaphors depend on pre-existing knowledge and real-world counterparts, there’s a limited pool of objects and actions from which UX designers can select to create a metaphor. Idioms, on the other hand, don’t have this constraint. As idioms come into existence by pure invention and shared use, this means UX designers can create however many they want, doing whatever they want. As interfaces are becoming increasingly complex, this freedom is crucial in exploring the possibilities of future interactions.
Metaphors Have Predetermined Functionality — Idioms Can Evolve And Adapt
Stubbornly sticking to the limited number of available metaphors means the UI design needs to adhere to the limited scope of associated functionality. While this may be acceptable for simple applications with few tasks, such as the infamous iBeer app, metaphors can grossly fail to scale as the application grows in complexity beyond the scope of the metaphor. A classic example is the folder management system for personal computers: as long as the user has few files, the metaphor works. But as soon as the system grows in complexity, the metaphor breaks down completely. Have you ever seen a physical filing cabinet with 10 nested folders? Yet on a personal computer, it would be unusual to find any less.
On the other hand, as a product grows and its UI design is continually and iteratively improved, the interface elements utilising idioms can be carried forwards or scrapped depending on their success, whilst maintaining the original essence of the idiom, and without detriment to the overall user experience. The computer mouse and scroll bar have no physical-world counterparts: their core functionality has translated nicely to the track pad and infinite scroll, respectively.
Metaphors May Generate False User Expectations And Be Culturally Dependent
When UX designers use metaphors, they often rely on their assumptions and expectations of their users, without considering the social and cultural biases people may have. For example, the colour white has different connotations in different parts of the world; and an icon of a cow might evoke different associations for a user in the US and a user in India. Moreover, users may vary in how strictly they believe the UI adheres to the metaphor. When you’ve got multiple storage drives connected to your computer, and there’s only one wastebasket on your desktop (who puts their rubbish bin on top of their desk, by the way?), would you not expect that to mean there’s the same one wastebasket for all your files? As idioms are first learnt in the context of their use, however, they don’t have the same pre-existing biases and expectations.
Metaphor Use Assumes The ‘Physical World’ Is The Mechanical Age — But This Is 2015
Do you tend to check the time on an analogue wristwatch or on your phone? When I say ‘copy and paste’, do you envision a photocopying machine and a paper glue stick or Ctrl/cmd + C and Ctrl/cmd + V? How many secondary school students today do you think know what a floppy disk is when they save their Word document?
The population of technology users is increasingly becoming one that grew up with personal computers, mobile phones, and web applications. Which makes more sense and is more efficient when calling a friend: searching alphabetically by typed name in a metaphorical address book app; or pointing at a picture of the friend to make a call? Just because certain objects and actions exist in the physical world doesn’t mean they should easily or rationally transfer to the digital world. Technology allows for so much more power and possibilities to what users can accomplish with their interfaces. Strictly adhering to physical world metaphors anchors and limits the UI’s functionality to the functionality of the physical world.
The human mind has an impressive capability of learning distinctive actions and remembering distinctive objects to accomplish things. This may even surpass its capability of inference and making mental connections.
That is not to say interface metaphors should be replaced entirely by interface idioms. Metaphors can be immensely powerful for evoking affective imagery, for instance via branding; attracting attention; and creating a sense of familiarity when interacting with technology. Moreover, metaphors have the advantage of being established in users’ minds, whereas idioms only become idioms after having been established and shared amongst several users, across different interfaces.
The challenge for UX designers thus lies in not only having the creative minds to develop idioms, but also in upholding certain core principles to ensure the idioms are developed for the user and not solely the convenience of the designer. Such principles include:
- Consistency: Avoid attaching different idiomatic meanings to the same objects or actions across multiple UI views, modes, applications, and systems. Consistency in the appearance and behaviour of idioms will maintain familiarity and user expectations.
- Distinctiveness: Idioms are successful when they are easy to remember and distinct from other UI objects and actions.
- Learnability: ‘All idioms must be learnt; good idioms need to be learnt only once.’ Do not overcomplicate the idioms when trying to incorporate distinctiveness, as users may not be able to learn how they work.
- Efficiency: Most of the time, users aren’t interested in understanding the interface, be it its underlying mechanisms or how the UI is conceptualised — they just want to get stuff done. Ensure that idioms help users accomplish what they want quickly and without hassle.
The key is knowing when to best utilise idioms and metaphors in interface design. Both offer strengths: metaphors are reliable and static, and have shown to be a great entry point for those new to personal computing. On the other hand, as modern cultures progresses further, classic metaphors become archaic puzzles of the past, exemplified by the floppy disk or rolodex. This stagnation calls for user interface design to increasingly embrace the use of idioms, the power of which lies in their fluidity and adaptability to the perpetually evolving culture of the modern day.
Jacob, R. J. K et al. (2008). Reality-based interaction: a framework for post-WIMP interfaces. In Proceedings of the SIGCHI Conference on Human Factors in Computing Systems (CHI ‘08). ACM, New York, NY, USA, 201-210.
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