actions affordances behavior complex constraints controls correct design determine discrepant easier easy error evaluation event everyday execution exploit factors feature forcing function give head human knowledge labels learn logical making mappings model natural number object people physical possible principles problem required state system things think thought used user visible world
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I know its been a while since I've posted anything of any significance. Work at Farm has been incredibly busy. Aside from the client work, we are expanding into (among other) areas such as research. Our new director of research and usability loaned me a classic, "The Design of Everyday Things" by Donald Norman. Like most professional books, it has some very pertinent and useful information... which is unfortunately buried by fluff, redundancy, and unnecessary examples. In any case, I like to take notes when I read or do research. I wish I knew who said it, but trusting the weakest pen over the strongest memory is definitely the way to go. What follows are my notes on Norman's work, complete with page numbers.
I hope you find these notes useful, and encourage you to follow up on any interesting notes with reading the respective section in the book.
Final thought: It really should be called "The Human Factors of Everyday things"
Notebook
The Design of Everyday Things
Warning Labels are signs of design failure
p. ix
Design of Everyday Things
If you think something is clever and sophisticated, beware - it is probably self-indulgence
p. ix
Design of Everyday Things
Ideally, there is no such thing as human error
A thought during p.2
Design of Everyday Things
Affordance refers to the perceived and actual properties that determine just how the thing could possibly be used
p.9
Design of Everyday Things
When rail shelters had glass, vandals smashed it. When they had plywood, vandals wrote on it. Planners are trapped by affordances of their materials
p.9
Design of Everyday Things
Fundamental principle of designing things for people
(1) Provide a good conceptual model
(2) Make things visible
p.13
Design of Everyday Things
Perhaps the designers thought the correct model was too complex, that the model they were giving was easier to understand. But with the wrong coneptual model, it is impossible to set the controls.
p. 17
Design of Everyday Things
If a feature is in the genome, and if that feature is not associated with any negativity, that feature hangs on for generations.
p.21
Design of Everyday Things
Whenever the number of possible actions exceeds the number of controls, there is apt to be difficulty
p.22
Design of Everyday Things
If you think that a room will heat faster if the thermostat is turned up all the way to the max, you are wrong. It is just an on/off switch
p.39
Design of Everyday Things
Everyone forms mental models to explain what they have observed [religion?]. In the case of the thermostat, the design gives no hint as to the correct answer. In the absence of external information, people are free to let their imaginitions run wild as long as their mental model accounts for the facts as the perceive them.
p.39
Design of Everyday Things
The Seven Stages act as design aides:
How easily can one:
- Determine function of the device?
- Tell what actions are possible?
- Tell if the system is in desired state?
- Determine mapping from intention to physical movements?
- Determine mapping from system state to interpretation?
- Perform the action?
- Tell what state the system is in?
- P.53
Design of Everyday Things
wherever labels seem necessary, consider another design
p.78
Design of Everyday Things
Not all of the knowlede required for precise behavior has to be in the head, it can be distributed - partly in the head, the world, and the constraints in the world.
p.54
Design of Everyday Things
Constraints reduce the number of options of the assembly of 10 components from 10! (~3.5M) to a manageable number.
p.62
Design of Everyday Things
The difficulty of dealing with novel situations is directly proportional to the number of possibilities
p.81
Design of Everyday Things
Affordances can signal how an object can be moved, what it will support, and whether anything will fit into it's crevices, over it, under it. Where do we grab, what parts move, and which parts are fixed.
p.83
Design of Everyday Things
Physical constrains are made more effective and useful if they are easy to see and interpret, for then the set of actions is restricted before anything has been done.
p.84
Design of Everyday Things
Semantic Constrains rely upon our knowledge of the situation and of the world. [Lego driver must have windshield to protect his face]
p.85
Design of Everyday Things
Culutural issues are at the root of many of the problems we have with new machines: there are as yet no accepted conventions or customs for dealing with them.
p.85
Design of Everyday Things
Physical, semantic, cultural, and logical constraints constrain our world.
p.84-87
Design of Everyday Things
The results of ANY action should be immediately apparent
p.100
Design of Everyday Things
One of the virtues of sounds is that they can be detected even when attention is applied elsewhere. But this virtue is also a deficit, for sounds are often intrusive.
p.103
Design of Everyday Things
When you build an error-tolerant mechanism, people come to rely upon it, so it had better be reliable
p.114
Design of Everyday Things
Human thought...seems more rooted in past experience than in logical deduction.
p.115
Design of Everyday Things
If there were a thousand similar events, we would tend to remember them as one composite prototype. If there were just on discrepant event, we would remember it, too, for by being discrepant it didn't get smudged up with the rest. But the resulting memory is almost as if there ahd only been two events: the common one and the discrepant one. The common one is a thousand times more likely, but not to the memory; in memory there are two things, and the discrepant event hardly seems less likely that the everyday one.
p.118
Design of Everyday Things
To see the relationship between the game of 15 and tic-tac-toe, simply arrange the nine digits into the following pattern:
8 1 6
3 5 7
4 9 2
p.126
Design of Everyday Things
Most major accidents follow a series of breakdowns and errors, problem after problem, each making the next more likely.
p.128
Design of Everyday Things
Although it may not at first seem to be relevant in design, [social pressure] has strong influence on everyday behavior. In industrial settings social pressure can lead to misinterpretation, mistakes, and accidents.
p.129
Design of Everyday Things
Designers make the mistake of not taking error into account. Inadvertently, they can make it easy to err and difficult or impossible to discover error or to recover from it.
- Understand the causes of error and design to minimize those causes.
- Make it possible to reverse actions - to "undo" them - or make it harder to do what cannot be reversed.
- Make it easier to discover the errors that do occur, and make them easier to correct.
- Change the attitude toward errors. Think of an object's user as attempting to do a task, getting there by imperfect approximations. Don't think of the user as making errors; think of the actions as approximations of what is desired.
Design of Everyday Things
Warnings signals, [like labels] are usually not the answer.
Design of Everyday Things
It is important to think through the implications of that cost [of normal behavior, for a forcing function] - to decide whether people will deliberately disable the forcing function.
p.134
Design of Everyday Things
The designer shouldn't think of a simple dichotomy between errors and correct behavior; rather, the entire interaction should be treated as a cooperative endeavor between person and machine, one in which misconceptions can rise on either side.
- Put the required knowledge in the world. Don't require all the knowledge to be in the head. Yet do allow for more efficient operation when the user has learned the operations, has gotten the knowledge in the head.
- Use the power of natural and artificial constraints: physical, logical, semantic, and cultural. Use forcing functions and natural mappings.
- Narrow the gulfs of execution and evaluation. Make things visible, both for execution and evaluation. On the execution side, make the results of each action apparent. make it possible to determine the system state readily, easily, and accurately, and in a form consistent with the person's goals, intentions, and expectations.
Design of Everyday Things
One negative force is the demands of time: new models are already into their design process before the old ones have even been released to customers.
[Try to give hard products characteristics of software]
p.143
Design of Everyday Things
In the world of sales, if a company were to make the perfect product, any other compan would have to change it - which would amke it worse - in order to promote its own innovation, to show that it was different. How can natural [Evolutionary?] design work under these circumstances? It can't.
p.143
Design of Everyday Things
Many of the useful refinements are being lost... All the folklore of design has been lost with the brash new engineers who can't wait to add yet the latest electronic gimmickry to the telephone, whether needed or not.
p.144
Design of Everyday Things
Designers often become expert with the device they are designing. Users are often expert at the task they are trying to perform with the device
p.156
Design of Everyday Things
Design is the successive application of constraints until only a unique product is left
p.158
Design of Everyday Things
A toaster offers affordances for danger. The location, the risk of burning a finger, and the narrow slots, all point to using a knife or fork, which can result in electrocution
p.164
Design of Everyday Things
When there is a problem, people are apt to focus on it to the exclusion of other factors. The designer must design for the problem case, making other factors more salient, or easier to get to, or perhaps less necessary
p.165
Design of Everyday Things
Whoever invented that mirror image nonsense should be forced to take a shower. Yes, there is some logic to it. To be a bit fair to the inventor of the scheme, it does work reasonably well as long as you always use the faucets by placing both hands on them at the same time, adjusting both controls simultaneously. It fails miserably, however, when one hand is used to alternate between the two controls. Then you cannot remember which direction does what.
p.169
Design of Everyday Things
Each new set of features adds immeasurably to the size and complexity of the system. More and more things have to be made invisible, in violation of all the principles of design. No constraints, no affordances; invisible, arbitrary mappings. And all because the users have demanded features.
p.175
Design of Everyday Things
One important method of making systems easier to learn and to use is to make them explorable, to encourage the user to experiment and learn the possibilities through active exploration
p.183
Design of Everyday Things
Design should
- Make it easy to determine what actions are possible at any moment (make use of constraints)
- Make things visible, including the conceptual model of the systems, the alternative actions, and the results of actions.
- Make it easy to evaluate the current state of the system.
- Follow natural mappings between intentions and the required actions; between actions and the resulting effect; and between the information that is visible and the interpretation of the system state
Design of Everyday Things
Design should make use of the natural properties of people and of the world:: it should exploit natural relationships and natural constraints. As much as possible, it should operate without instructions or labels. Any necessary instruction or training should be needed only once; with each explanation the person should be able to say, "Of course", or "Yes, I see". A simple explanation will suffice if there is reason to the design, if everything has its place and its function, and if the outcomes of actions are visible.
p.188
Design of Everyday Things
The principles of design are straightforward
- Use both knowledge in the world and knowledge in the head
- Simplify the structure of tasks
- Make things visible: bridge the gulfs between execution and evaluation
- Get the mappings right
- Exploit the power of constraints: both natural and artificial
- Design for error
- When all else fails, standardize.
Design of Everyday Things
Actually, increasing the number of controls can both enhance and detract from ease of use. The more controls, the more complex things look and the more the user must learn about it. It becomes harder to find the appropriate control at the appropriate time. On the other hand, as the number of controls increases up to the number of functions, there can be a better map between controls and functions, making things easier to use. So the number of controls and complexity is really a tradeoff between two opposing factors.
p.209
Combine this with using human factors laws to determine size, qty, and number of controls.
Design of Everyday Things
In the consumer economy taste is not the criterion in the marketing of expensive food or drinks, usability is not the primary criterion in the marketing of home and office appliances. We are surrounded with objects of desire, not objects of use.
p.216
Design of Everyday Things
Good design exploits constraints so that the user feels as if there is only one possible thing to do - the right thing, of course.
p.216
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