Kristen Reay

HCI — Week 5: Manipulation and Representations — Part I

“The key innovation of a graphical user interface, is that input is performed directly on top of output.” - Scott Klemmer

• Simply asking people what they wants may cause you to miss opportunities.

Questions to use when looking for where challenges arise.

1. How easily can someone determine the function of the device?
2. How easily can someone tell what actions are possible?
3. How easily can someone determine mapping from intention to physical movement?
4. How easily can someone perform the action?
5. How easily can someone tell what state the system is in? / If its in desired state?
6. How easily can someone determine mapping from system state to interpretation?

Command Line vs. GUI

What is better? It depends! But what makes them different. Command lines require knowledge, they don’t give immediate feedback, and they don’t leverage metaphors for things humans already know. The GUI does a better job in terms of visibility, feedback, and consistency. GUI’s shine in discoverability. 

When is the command line better? When the indirection that it offers is a benefit rather than a draw back. This is powerful when you can express stuff more abstractly and therefor do things more efficiently. 

Mental Models - What makes an interface learnable and what leads to errors in user interfaces. 

“There’s a big pitfall in being a designer, you’ve spent so much time with the system that you know how it works under the hood and how you imagine other people will think about it. Your expertise can be crippling, the mental model that you expect users to have, you expect it to be the same as yours and it doesn’t play out in practice.” - Klemmer.

That’s why it’s important to get other users in front of your design as soon as possible. 

Slips vs. Mistakes

Slip - the right model for the system and how it works, but you accidentally do the wrong thing. A motor error.

Mistakes - when you do what you intend to do, but you have the wrong model. Driving, you think you should take an exit, but it turns out to be wrong. 

• Designers try to prevent these errors. Slips can be prevented to avoid slips. Designers need to provide better feedback to avoid mistakes.

Presentation Matters

“The ways in which we and the world organize and represent ideas can have a drastic impact on our cognitive abilities.” - Scott Klemmer

“Solving a problem simply means representing it so as to make the solution transparent.” - Herbert Simon, The Science of the Artificial

Naturalness Principles

• Experiential cognition is aided when the properties of the representation match the properties of the thing being represented.
• Integrating the necessary step with the natural step makes you not forget the necessary step. 

Book suggestion: Don Norman’s, The Design of Everyday Things.