‘The Design of Everyday Things’. Donald A. Norman.

1. ‘The Design of Everyday Things’.Donald A. Norman. “Design is the successful application of constraints until only a unique product is left”

2. You will soon know these important concepts for designing everyday things - Affordances - Visibility - Feedback - Mapping - Conceptual models - Constraints - Consistency

3. Affordances “the perceived and actual properties of the thing, primarily those fundamental properties that determine just how the thing could possibly be used” • Affordances provide strong clues to the operation of things. • Chairs support therefore, affords sitting on. • Buttons are for pressing • No picture, label or instruction is required

6. Handles are for lifting, but these are for scrolling!

7. Feedback Sending back information to the user on what has been done. The user should receive full and continuous feedback about results of actions. Imagine drawing with your eyes closed… ‘Feedback is a well known concept in the science of control and information theory’. D Rosenberg

9. Feedback Delays in feedback create confusion and lack of confidence in user. Feedback Audio, Tactile, Visual, Output – digital, sensors, mechanical actions etc Mikael Fernstrom – earcons Krispin Laydon – Vibro tactile search.

12. Can only push,side to push clearly visible Which side? Push or pull? Constraints • limitations of the actions possible, perceived from object’s appearance provides people with a range of usage possibilities

14. Constraints are ways of restricting the kinds of actions a user can take. Physical constraints – the objects size or shape stops certain actions from occuring Logical consrtaints – relys on common sense (gravity) Cultural constraint – localised signals

15. Mapping The relationship between two things. • visible mapping and mimic diagrams: stove and controls • cause and effect: steering wheel-turn right, car turns right

17. Good mappings It is possible to determine the relationships between: • Actions and results (Cars) • Controls and their effects (VisiBreath) • The system state and what is visible(hourglass cursor)

18. Visibility • the thing that happens right after an action is assumed by people to be caused by that action False causality - incorrect effect invoking unfamiliar function just as computer hangs causes “superstitious” behaviors

19. Effects are visible only after Exec button is pressed • Ok does nothing! • awkward to find appropriate color level

20. invisible effect • command with no apparent result often re-entered repeatedly • e.g., mouse click to raise menu on unresponsive system

21. Conceptual Models A conceptual model allows the user to simulate the operation of the device. A good conceptual model allows the user to predict the effects of their actions. Therefore; Making things visible By looking, the user can tell the state of the device and the alternatives for action. Uses spatial and mechanical reasoning

22. Can this function as a bicycle for two?

24. People often refer to this as having a, Mental map Or Mental model

25. Transfer effects • people transfer their learning/expectations of similar objects to the current objects • positive transfer: previous learning's also apply to new situation • negative transfer: previous learning's conflict with the new situation

27. Localised Expections Populations learn idioms that work in a certain way, red means danger? green means safe? Light switches America: down is off Britain: down is on Faucets/Taps America: anti-clockwise on Britain: anti-clockwise off

28. Designing good concepts communicate model through visual image • visible affordances, mappings, and constraints • visible causality of interactions • cultural idioms, transfer • instructions augments visuals

30. Consistancy Be consistant in your design choices!

31. Good Design: Scissors • affordances: • holes for something to be inserted • constraints: • big hole for several fingers, small hole for thumb • mapping: • between holes and fingers suggested and constrained by appearance

32. positive transfer and cultural idioms • learnt when young • constant mechanism conceptual model: • implications clear of how the operating parts work

33. Bad Design: Digital Watch • affordances: • four push buttons to push, but not clear what they will do • constraints and mapping unknown • no visible relation between buttons, possible actions and end result • transfer of training • little relation to analog watches

34. cultural idiom • somewhat standardized core controls and functions • but still highly variable • conceptual model: • must be learnt

38. Why? Endeavors to provide an understanding of both the human user and the computer system, in an effort to make the interactions between the two easier and more satisfying.

39. many so-called human errors are actually errors in design • human factors became important as human performance limitations are reached when handling complex machinery • Britain 1976 • Motorway communication system operated 40% of it’s highways • police controlled it in real time to • change lane signs, direction signs, speed limits, etc

40. On December 10th, police failed to change the speed limit signs when fog descended • 34 vehicles crashed • 3 people killed • 11 people injured and trapped in their vehicles • motorway closed for 6.5 hours

41. Police (at inquest) • “The system did not accept the instruction” • Dept of Transport (after examining computer logs) • “There is no evidence of technical failure”

42. System designers • after emphasizing that they have no responsibility for the system • “We supplied it over 5 years ago and have never been called to look at that problem” • The Coroner’s court • judged it as "operator error" • the police operator: “failed to follow written instructions for entering the relevant data”

43. Caller: Hello, is this Tech Support?“ Tech Rep: Yes, it is. How may I help you? Caller: The cup holder on my PC is broken and I am within my warranty period. How do I go about getting that fixed? Tech Rep: I'm sorry, but did you say a cup holder? Caller: Yes, it's attached to the front of my computer. Tech Rep: Please excuse me if I seem a bit stumped, it's because I am. Did you receive this as part of a promotion at a trade show? How did you get this cup holder? Does it have any trademark on it? Caller: It came with my computer, I don't know anything about a promotion. It just has '4X' on it.

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