Thoughts on layers for design

Defining interaction style helps work on multiple layers

Posted on: November 02, 2009 by: Vesa Metsätähti in: Thoughts on layers

Interaction style is something I was thinking to define back in late 90’s. Early in 2000 there was not much “leisure” type software (not counting games as they are a bit of different stuff than what we are looking for here). Software (and hardware?) for consumer digital photography — specially the one bundled — was quite awful.¹ Although the idea of defining interaction style got going with tangible products and user interfaces this model was brushed up in software related projects.

The model became very important with software embedded products and services. Some of the such projects that I have worked with treated the physical side of the product as a sculpture, and design of it’s behavior as a totally different unrelated project.²

The reasons for needing a way to define interaction style was that:

1. the way something works defines it just as much as it’s physical appearance
2. the way something works needs to correlate with the physical appearance and other manifestations of product or service (advertisements, packaging, physical appearance, etc. give promise on what the product or service will be like, if they tell a different story or lie the customer will be extremely disappointed: “this car looks like Audi but drives like Opel”)
3. in the future with ubiquitous computing what defines the experience is not what we use but how we use it (you might be using handset of X but control device of Y – and the X might be quite transparent: “on this car my steering wheel drives like an Audi”)

Interaction style can be defined with the relationship of controls and feedback

The range of controls in the model is from casual to conscious. Casual controls include anything that has not been specifically designed for the use (or where use is not specifically designed for being controlled by), and/ or that do not provide high, exact, motivated or sensible way to tackle the task.

In this model the feedback ranges from plain to rich. Feedback is a bit tricky to evaluate since it doesn’t not naturally fit inside such a one dimensional continuum. Rich interaction would be something like a melody instead of simple sound. Richness or plainness is relative and is found by comparing feedback to what else it could (realistically) be or what other conventions there currently are or have been.

In our diagram feedback is located on the horizontal axis and controls on the vertical axis. Thus in the lower left corner we have an area where we have find plain feedback and arbitrary controls. In the upper right corner we have place for stuff with rich feedback and conscious controls. The interaction in rich feedback and conscious controls can be categorized as tool like interaction. Interaction with rich feedback and arbitrary controls can be categorized as toy like interaction.

In a sense this describes the relationship of stuff on the task layer and stuff on the presentation layer. More importantly, this is a tool for work in the task layer to define what kind of feedback the presentation layer should consider. It is up to the presentation layer to decide what the feedback actually is.

Feedback changes between primary and some secondary media

Primary media is what you would think of as a natural output or feedback of your actions. Secondary media is something added, more artificial etc. For tool like interaction secondary feedback will give more detailed view of the matter, usually in such detail that it will be redundant for a layman. With toy like interaction the secondary media will make the natural feedback more visible, understandable or cover lack of natural feedback.

As an example four different audio tools. For all of them the primary media is sound.

In lower right corner we have mini stereo system. There can be a lot of controls (shiny ones) but they perhaps have little or inaccurate effect on the sound the stereo system produces. That does not really matter for the user to know the stereo system sounds good through the flashing lights it has: the secondary media. Clearly a case of toy like interaction.

In lower left corner we have portable radio. Not too many buttons and not too deep controls. For feedback to know that you are playing the correct radio station is enough (even as they tell what station you are listening to, they fail if you do not recognize it through the selection in program). Lets call this straightforward interaction.

In upper left corner we see record players of a DJ. There can be plentiful controls but the largest are the most important – by spinning the decks the DJ is in full control of how the music is played. Even as there can be a handful of feedback to help DJ in her job, the real professional trusts only her ear listening how the music sounds. Direct manipulation perhaps?

In upper right corner is an image of studio mixer. Studio has accurate control on many things and technician trusts in her ear evaluating the sound. Additionally she will get a bunch of additional feedback on sound levels etc. Tool like interaction.

There is no right combination and good usability can be found in all of them

Unlike with some diagrams there is no preferred combination. The “correct” choice depends from the context and goal. (Working with a high-end lawn mover should not feel toy like – unless that is for some reason specifically decided to be the thing that sets it apart from the rest. But even then the physical and visual world should have some sort of connection to the toy-like-ness or it will feel detached and unmotivated).

Good design and usability can be found from each category. (The straight forward portable radio is actually the most stylish one of the example devices). The important thing is to know what part of the product or service will fall in to which quadrant and communicate it.

Sometimes thinking of one quadrant is forced on every part of a product. But not everything has to behave similarly — it is more important to behave appropriately than “logically”. In a health care device the examination process can be direct manipulation or perhaps tool like interaction (depending on the application of course). Selecting a current patient from database should however be straightforward and not forced to work like direct manipulation for example.

Now how does this relate with the 4 layers for design?

The interaction model is useful tool for:

• generating designs — trying out how the product or service would be like if executed in another quadrant for example
• validating design — evaluating if the design fits in the defined interaction style
• communication — it is easier to get the design right if different professionals have common terminology for this kind of abstract stuff

Much of the documentation related to design work is directed at the infrastructure layer. Interaction style is something that is useful as a mental tool for the designer and as a communication method for other designers. It will be less likely useful as documentation for implementation.

Footnotes aka. Excel turns to a bad toy when added with “fancy GUI” etc.

¹ The software bundled with cameras (and most early digital boom image editing and organizing software to that matter) was tool like interaction stuff that did not really relate to photography. To make them look more humane they were added with bloated graphics and some times more “advanced” functions were hidden somewhere, resulting in sorry toy like interaction coupled with bad usability.

² The products or services were thought usually through models (like Peter McGrorys 4 dimensions of product identification) that were then forcibly applied to statue like design objects — with some vague brand value on background and physical features that were designed in the end (and value, behavior happening magically somewhere between).

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