Thursday, February 21, 2019

Basic interaction design principles

I'm wrapping up my first course on human-computer interaction, and I've learned three sets of fundamental interaction design concepts. Essentially, this is common sense, formalized. But still a very useful body of concepts to know and that can be applied beyond interaction design.

Norman principles 

Delineate the elements of interaction design. Demonstrated below are good examples of each of those elements.

  • Affordances and signifiers. In other words, functions and perceivable indicators of that function.
Image result for doorknob
Ex: A doorknob signifies the affordance of pushing.

  • Mapping. When controls are mapped in a way to enable function.
Image result for piano app
Ex: A piano app's buttons are mapped naturally to an actual piano. [Flickr]

  • Feedback. A confirmation that the function is successfully (or not) executed. 
Image result for bell doorbell
Ex: Bell doorbell makes audible sound when rung. [Wikimedia Commons]

  • Constraints. Prevents user from engaging in improper function.
File:Stop sign and road markings.JPG
Ex: A yellow line at a stop sign (usually) prevents drivers from crossing without stopping. [Wikimedia Commons]

  • Visibility. When affordances are easily discoverable.
File:Japanese Electric Water Boiler 20101026.jpg
Ex: "On" light-indicator shows the boiler is on. [Wikimedia Commons]

  • Models. When an end-user's mental representation of how something works matches with the way the system/product actually works. Varies from person-to-person.

Gestalt principles 

Are rules on how to organize content according to conventional human perception. The list includes key ideas about how our brain tends to visually simplify the complex.

  • Proximity. Objects that are close to one another tend to be mentally grouped together.

  • Similarity. Objects that are similar to one another in size, shape, and/or color are grouped together.

  • Closure. The mind completes familiar objects and patterns when elements are missing.
╭  ╮

  • Continuity. The mind continues patterns and lines, even in case of interruption.

  • Symmetry. We parse complex scenes in a way to reduce complexity.
◢◣ ⋘⋙ 【】⦅ ⦆

  • Figure/ground. Our mind separates a scene into figure (foreground) and ground (background).
Courtesy of roy from Alt-codes.

  • Common fate. Elements with the same movement (speed and/or direction) are seen as a single unit.


Jakob Nielsen's Usability Heuristics 

These broad rules of interaction design help make a great and user-friendly product.

  • Visibility of system status. Keep users informed about system state.
Maya with error highlight to the right of Command Line.
Autodesk Maya has a neat message bar at the bottom showing the results of every action.
  • Match between system and the real world. Speak the user's language and speak in a natural, logical way.
"Deal enough damage and you win!" Blizzard's Hearthstone.

  • User control and freedom. Users need to be able to exit, undo, redo.
"(ESC)exit" command is persistently in view for the user.

  • Consistency and standards. Users shouldn't be confused by similar words (keep use of vocabulary consistent) and have to think whether or not they mean the same thing.




  • Error prevention. Users should prevent errors and give users confirmation messages.
Image result for are you sure you want to delete
"Are you sure you want to move this file to the Recycle Bin?" Windows PC.

  • Recognition rather than recall. Minimize users' memory load by making objects, actions, and options visible.
All of CellPaint's commands are on the interface.

  • Flexibility and efficiency of use. Offer tutorials for beginners and accelerated options for expert users.
LyricsTraining app to learn languages through music.

  • Aesthetic and minimalist design. Extraneous info competes with relevant units of info and diminishes their relative visibility.
Neopets has really gone downhill since being sold to Viacom.

  • Help users recognize, diagnose, and recover from errors. Use plain language to offer a solution.
"Program removal failure. You must restart Windows to completely remove the program." error message well done.

  • Help and documentation. For complex software, it might be necessary to provide documentation that is easy to search, lists concrete steps, and isn't too large.
Canva has a very helpful Help button at the bottom-right of the screen.

There you have it! A very simplified overview of design concepts to get you started thinking about your next project.

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